Category Archives: Ocala National Forest

Thrush passages

December 30, 2016

It was late in December, the sky turned to snow
All round the day was going down slow
Night like a river beginning to flow
I felt the beat of my mind go
Drifting into thrush passages
Years go falling in the fading light
Thrush passages
– Al Stewart

If you’re reading this, Al Stewart, please forgive the liberties I’ve taken with your lovely lyrics. This song popped into my head sometime in the last month or two while reveling in the passage of the spot-breasted thrushes through the state, and it has become firmly embedded since. Now, every time I see or think about a thrush, I can’t stop myself from replaying this song in my head, even though it doesn’t really speak to my circumstances very accurately. Snow in Florida? Not likely.

During the past five months, I’ve thoroughly enjoyed of one of the finest perks academia has to offer – the sabbatical. Intended as a semester of research, reflection and rest from the typical mind-numbing responsibilities of teaching, a sabbatical leave is granted to applicants who propose scholarly work that the Professional Development Committee deems worthy. For my fourth and final sabbatical (we are eligible for one every 7 years), I hoped to spend the entire semester in the field studying bird behavior. And it was approved, praise be to the committee. University committees do on occasion accomplish worthwhile stuff.

flatwood-sunrise_10312016-10_tiger-bay-n

Sunrise in the flatwoods of Tiger Bay State Forest. Being afield at sunrise at a different site each day of the week was an amazing experience.

As a result of the committee’s sage decision, I had the incredible privilege of being afield on over 60 days this semester. Some of my study sites included Lake Woodruff National Wildlife Refuge in DeLeon Springs, Chuck Lennon Park, also in DeLeon Springs, Heart Island Conservation Area near Barberville, Lake George Conservation Area near Seville, Tiger Bay State Forest and Wildlife Management Area east of DeLand, and my favorite, Forest Road 33 in Ocala National Forest. Being in the field at sunrise nearly every day during Florida’s fall migration (which begins for songbirds in mid-July with the arrival of the first yellow and prairie warblers) provided me the opportunity to experience fall migration in a depth I could scarcely have imagined back in mid-August when I began the project.

As one of the greatest experiences of my life has come to an end, I’ve begun to reflect on some of the more notable sightings and insights I’ve gained about the comings and goings of birds during the past five months. The passage of the spot-breasted thrushes is at the top of that list.

Veeries are the first of the Catharus thrushes to migrate through Florida.

The spot-breasted thrushes include 6 species, most in the genus Catharus, along with the wood thrush, placed by some in its own genus, Hylocichla. Wood thrushes were the only one of the six species I didn’t see this fall (maybe; distinguishing 2 of the 5 species of Catharus is nearly impossible in the field without hearing vocalizations). I don’t recall ever seeing a wood thrush in Florida, though they are fairly common (though declining) breeding birds of eastern deciduous forest in much of eastern North America. They breed sparingly in the peninsula, and are rare as migrants through the state.

Wood thrushes are hard to find in Florida, though they are widespread breeders in eastern deciduous forest of the eastern half of the U.S.

Thrushes are birds of mystery to me. Most are primarily forest-dwellers, at least in migration, and are notable for their shy, inconspicuous ways. Furtive, fond of dense cover, and easily spooked, getting a good look at some of these birds is no mean feat. Prior to this fall, I had never seen more than two or three species during any single fall migration period.

Thrushes are primarily forest birds.

Perhaps the most interesting feature of fall thrush migration to me is the protracted time period over which it occurs, combined with the very predictable chronological sequence of appearance of each species through Florida. All of the early migrating species leave the state to winter in the tropics, while the hermit thrush arrives last and remains in small numbers as a winter resident.

In a nutshell, the order of appearance of the Catharus thrushes during fall migration is as follows: veeries form the vanguard, arriving as early as late August, followed by Swainson’s and gray-cheeked/Bicknell’s thrushes in mid-fall, peaking in October. These three species are followed by the caboose of the bunch, the hermit thrushes, which start appearing in force in November and stick around for the winter in small numbers.

Swainson’s thrushes are usually the most abundant of the mid-fall migrants.

This extended movement of Catharus thrushes through Florida raises a bit of a conundrum. All of these species are breeding birds of the far north. All breed in forested or semi-forested habitats of the northern tier of states and in Canada, and all feed largely on insects and other invertebrates during the breeding season, supplementing their diet during fall migration heavily with energy-rich fruit. So they all have a broadly similar ecology and have roughly the same migratory task – traveling from the high temperate to the tropics (or just to Florida in the case of some hermits). Yet the timing of their departure and passage through Florida is so different. I have no idea why that is so, and my time in the field with these birds this fall provided no great insight, but who cares? It’s enough just to watch them and ponder.

Bill Pranty’s indispensable A Birder’s Guide to Florida contains a wealth of useful data about the timing of migration of all of Florida’s birds. One of its most useful features is the information-rich bar graphs depicting seasonal occurrence and abundance of each Florida bird species. According to Pranty, veeries (Catharus fuscescens) first appear in Florida in late August and can be found as late as November, but peak in September and October, when they are rated as uncommon (found in small numbers; “sometimes, but not always, found with some effort in appropriate habitat”). They are rare before September and after October.

Veeries are one of the easier Catharus thrushes to identify. Their sparsely spotted chests and uniformly fuscous upperparts are distinctive.

I saw veeries on four days this fall, all in September. I saw my first veeries, a group of 3 birds foraging on the forest floor in mixed forest, at Heart Island Conservation Area on September 9. I saw veeries again on September 14 in the mixed cypress swamp/flatwoods of Tiger Bay State Forest (north entrance), on September 16 in mixed hammock/flatwoods of Tiger Bay (Rima Ridge tract), and for the last time on September 20, in the sand pine scrub of Ocala National Forest. Like most of these thrushes, getting a clear, unobstructed look at or photo of these shy birds is a challenge. I was fortunate to photograph them on 3 of the 4 days I saw them.

Veeries breed across most of the northern tier of states in the U.S. and in southern Canada, where they can be found in thick, wet deciduous woodlands. They are especially fond of early successional forest or disturbed areas in mature forest, and can also be found in mixed deciduous-coniferous forest.

A veery in the cypress wetlands of Tiger Bay State Forest.

Veery in the scrub of Ocala National Forest. Like all of the Catharus thrushes, they are quite shy and prefer to be partially obscured by cover.

The next arrival of migrant thrushes occurs mostly in October, when three species (gray-cheeked, Bicknell’s, and Swainson’s) pass through in largest numbers. Of the three, Swainson’s thrushes (Catharus ustulatus) are more easily seen. Pranty’s bar graphs show Swainson’s thrushes present in Florida from September to early December, with a peak in the latter half of September and throughout October, during which period they are rated as uncommon (rare before and after these dates).

I saw Swainson’s thrushes on only one day this fall. On October 4, they were abundant in the sand pine scrub along Forest Road 33 in Ocala National Forest. I saw at least 10 birds, and photographed 4 or 5 individuals. Swainson’s thrush is for me the most common of the early-migrating thrushes. I see them most years at least once during fall migration.

The buffy cheeks, prominent eye ring, and partial spectacle make Swainson’s thrush a pretty easy ID if you can get a good look at the head. Which isn’t always easy.

Swainson’s thrushes also have an extensive breeding range, nesting in the northeast U.S. and in some of the Rocky Mountain states, and throughout much of Canada and Alaska, where they are found in boreal coniferous forest.

There are two Swainson’s thrushes in this shot, and as is typical, both are deep in cover.

Swainson’s thrush

The other two species whose timing of passage roughly coincides with that of Swainson’s thrush are a puzzle. Gray-cheeked (Catharus minimus) and Bicknell’s (Catharus bicknelli) thrushes were considered conspecific (belonging to the same species) until the ‘90’s, when Bicknell’s thrush was recognized as a separate species with a very restricted breeding range. Given that these two species were considered one until only recently, it shouldn’t be a great surprise that they are VERY difficult to separate in the field based only on visible cues. They are nearly identical. Consequently, the phenology of Bicknell’s thrush migration through Florida is poorly understood, simply because there are so few confirmed sightings. Those sightings that have been confirmed suggest Bicknell’s tends to stick closer to the coastline during migration than the gray-cheeked.

Gray-cheeked and Bicknell's thrushes are nearly identical. Some of the bird ID experts at the Florida Rarities FB page were unable to determine which this bird is.

Gray-cheeked and Bicknell’s thrushes are nearly identical. None of the bird ID experts at the Florida Rarities FB page were able to determine which species this bird is.

Pranty’s bar graphs show that gray-cheeked thrushes pass through the state in September and October, and are considered rare throughout this period. There are only a handful of confirmed Bicknell’s thrush sightings during fall migration in Florida, so the timing of their migration is largely unknown.

My only sightings of these two species in the field were also on October 4 in the mixed scrub along FR33 in Ocala NF. Prior to this fall, I had seen gray-cheeked thrushes only once or twice in my life, and I had never seen Bicknell’s thrush. I may have seen both species this fall, but can’t be certain because of the difficulty in separating the two.

This presumed gray-cheeked thrush died from a window strike at my home on October 2.

Coincidentally, my first sighting of a thrush in this species complex was on October 2, when I found a window-killed thrush in my backyard. As far as I can tell, it is a gray-cheeked thrush. Gray-cheeked and Bicknell’s thrushes can apparently be identified with confidence based on specific measurements of live or dead birds in hand, but that’s beyond my skill set. That bird, which is in perfect condition, is still in my freezer. Maybe someday I’ll get a definitive ID.

This bird showed interest in the songs and vocalizations of gray-cheeked thrush, but remained deep in cover.

Tuesday, October 4, was one of the most memorable days of the fall for me. Thrush day in the scrub. In addition to the numerous Swainson’s thrushes I saw that day, I also saw a few birds that were either gray-cheeked or Bicknell’s thrushes. Especially intriguing was the observation that one of these birds responded strongly to playback of vocalizations of Bicknell’s thrush, but only mildly to those of the gray-cheeked thrush. I first saw this bird as he skulked through the dense foliage of scrubby oaks, approaching in response to playback of mobbing vocalizations, the main subject of my research. When I realized what it might be, I played territorial song of both Bicknell’s and gray-cheeked thrushes to this bird. Gray-cheeked song resulted in continued skulking. Bicknell’s song caused him to immediately pop out onto an exposed perch maybe 25’ away, where he remained for a minute or so, tail-pumping and wing-flicking.

Playback of Bicknell’s song caused him to immediately pop out of deep cover onto an exposed perch.

So that had to be a Bicknell’s thrush, right? Unfortunately, no. It’s not unheard of for some thrushes to respond strongly to territorial song of other species. I’ve seen hermit thrushes become very agitated in response to veery song playback. I posted photos of the unknown thrush, along with a description of his playback response, to the Florida Rarities Facebook group, and nobody in that group of expert birders would attempt an ID. My conclusion – most likely a gray-cheeked, but perhaps a Bicknell’s.

Gray-cheeked thrush, probably.

Especially intriguing to me is that these birds respond to territorial song at all while they are on migration. None of these species sings regularly during migration, yet they will occasionally respond vigorously to song playback of conspecifics, and sometimes heterospecifics. Why? Use of playback to attract birds for observation/photography is a contentious subject, and some purists frown on the practice. Certainly it can be overused and abused, but I can’t imagine birding without using playback carefully and judiciously as a tool. The observation that these transient migrants still respond to territorial song is telling us something about the biology and behavior of these birds, even if we don’t know exactly how to interpret that observation. Such basic natural history observations are the foundation of a complete, nuanced understanding of any species. I’ve offered a defense of playback as a vital tool for birding in a previous blog.

So on October 4, I saw 4 different birds that were probably gray-cheeked thrushes, but may have included a Bicknell’s or two. What a conundrum, right? Can I place Bicknell’s thrush on my life list? In all honesty, I don’t really give a rat’s ass. I’m not and never have been a lister or twitcher. I don’t even know what my life list is numerically, though I have a pretty clear memory of which species I have and haven’t seen. I’m totally cool with calling those birds either gray-cheeked or Bicknell’s thrushes. Or both.

Gray-cheeked thrush, probably.

Gray-cheeked thrushes are the more likely of the two species to be seen in migration along most of the east coast. They have a continent-wide breeding range, extending across northern Canada and Alaska. Gray-cheeked thrushes are the most northerly of the spot-breasted thrushes in their breeding distribution; they breed in spruce-fir forest, and in alder and willow thickets on the tundra. Bicknell’s thrush has a far more restricted breeding range in southeast Canada and the northeast U.S., where they are mostly restricted to inaccessible regenerating montane forests of spruce and fir. This is a very poorly studied and understood species.

Hermit thrush in the golden light of dawn from the scrub of Ocala National Forest.

The easiest Catharus thrush to see in Florida is the hermit thrush, Catharus guttatus. This is the most abundant member of the genus in the state, and is also resident in Florida for far longer than the others. Pranty shows them as being uncommon in October, and fairly common from November through March. Unlike all the other members of its genus and the closely related wood thrush (Hylocichla mustelina), hermit thrushes overwinter in significant numbers in Florida. Hermits are also one of the easiest of the spot-breasted thrushes to identify; there’s not much temporal overlap between hermits and the transient thrushes, and the distinctive rufous wings and tail of hermits make ID relatively straightforward. If you can get a good look at one.

My first hermit thrush of the fall, from November 1 in Heart Island Conservation Area.

I saw my first hermit thrush of the season on November 1 in the dense riparian hammock along Deep Creek in Heart Island Conservation Area. I actually heard it first. Hermit thrushes are extremely responsive to playback of their alarm calls (churt and way calls), and will also respond to territorial song, though they don’t sing often while in Florida. They do defend fixed winter territories, though, which is an unusual behavior for wintering passerines.

I photographed this territorial hermit thrush in Ocala National Forest several times in the winter of 2015-16.

I photographed this territorial hermit thrush in November 2016, in the exact same location as the bird above. I’m pretty confident it’s the same bird that returned to overwinter on the same territory. That’s some wicked winter philopatry.

The high abundance of hermits relative to their congeners may be related to their broad breeding range, throughout Canada, the Rockies, and the northern U.S., and their catholic choice of habitat for nesting. They can be found breeding in both coniferous and deciduous forest, mixed forest, taiga in the extreme north, and in riparian woodlands in canyons of the Southwest.

Hermit thrushes have the largest breeding range of any of the Catharus thrushes, and nest in a greater variety of habitats. This one was found in a bayhead at Lake George Conservation Area.

And they are abundant. Once I saw my first, I saw hermit thrushes on the majority of my field days for the remainder of the study period. Particularly during the first couple of weeks in November it wasn’t uncommon to see a half-dozen or more hermits in a day. They became somewhat less common in December, as the pulse of migration passed and many of the migrants continued on to winter in the tropics. The abundance of hermit thrushes in winter can be stunning at times. During Christmas vacation of 2013, we found dozens of hermit thrushes in the coastal forests of South Carolina.

Hermit thrush performing self-inspection.

Hermit thrush doing his happy dance.

The spot-breasted thrush that I didn’t see this fall is one I am quite familiar with as a breeding bird in Virginia, where wood thrushes are fairly common (but declining) breeders of moist deciduous forest. This is the one spot-breasted thrush I have heard singing on their breeding grounds. The polyphonic, lush, complex, flute-like songs of wood thrushes ringing through mature oak-hickory-beech forest at dawn or dusk are emblematic of this cathedral-like habitat for me. The thrushes are the pipe organs, only far more delicious. The experience of hearing a wood thrush singing in majestic mature deciduous forest is so thrilling that I found myself imagining over and over this semester again how magical it must be to hear all of these northern thrushes singing in their pristine breeding habitats.

Wood thrushes have proven to be the most difficult thrush to photograph, for me, though they are not hard to find during the breeding season.

I don’t recall ever seeing a wood thrush in Florida, where they are actually breeders in the Panhandle. As fall migrants through the peninsula, however, they are rarely encountered. Perusal of e-bird sightings in the peninsula for the period August-November 2016 turned up less than a dozen sightings. Yet another mystery of thrush biology – why are nearly all of the northern-breeding thrushes so much more abundant in fall migration through Florida than wood thrushes? Why do wood thrushes mostly avoid migrating through the peninsula?

A Florida wood thrush would be a first for me.

The other two commonly seen Florida thrushes, quite different in nearly all aspects of their biology from the Catharus and Hylocichla thrushes, are equally curious in their movement patterns. American robins are winter residents in the state, and are the last of the migrant thrushes to appear. Though they winter in huge numbers in the state, they also show quixotic behavior while here – they show a distinctly biphasic nature of habitat choice and behavior while wintering, a phenomenon I’ve written about in a previous post (Bipolar Robins).

American robins winter in huge numbers in Florida, but not until the transient thrushes have mostly completed their passage.

The other common Florida thrush is the eastern bluebird, which is dramatically different in behavior from the woodland thrushes. Not only are bluebirds denizens of open, non-forested habitats and edges, they are also permanent residents. No migratory movement at all. Like robins, young birds show spots on the breast typical of so many thrushes.

Eastern bluebirds are non-migratory thrushes that breed throughout Florida.

Like most thrushes, the young of eastern bluebirds show the spotted breast that is part of the adult plumage of many thrushes.

The woodland thrushes are special birds for me; seeing even one of these shy, cryptically-patterned birds elevates any birding trip to a good day. For the rarer species, like gray-cheeked thrushes, seeing them once during the migratory season is a significant event. To see secretive, uncommon birds you have to have a bit of skill, a bit of luck, and spend lots of time in the field. It’s noteworthy to me that though I spent over 60 days in the field this fall, I saw three (maybe?) of these species on only one of those days. Though all of these species are regular fall migrants through the peninsula, the vagaries of weather and frontal patterns, prevailing high-altitude winds, and other meteorological variables that impact migratory flights over and into the state all combine to make finding these birds, and in particular the rarer species, a daunting challenge. I was quite lucky this fall.

I love observing and photographing birds with such intensity that I would do what I do if there were no other rewards than the sightings, the photos, and the memories. Equally rewarding for me, though, is the window these observations provide into the workings of the natural world. Natural history is an infinitely complex subject; any one of us can only hope to scratch the surface over the course of a lifetime of study. A lifelong attention to the minutiae of natural history provides a deep understanding of the meaning of one of the great buzzwords of our time, biodiversity. Biodiversity is more than a list of species, though it is sometimes simplified to simple numeration of species numbers.

Migrant thrushes and fall foliage – a hard-to-beat combination. This is a hermit thrush in red maple (Acer rubrum).

The Catharus thrushes illustrate some of the finer points of biodiversity perfectly. Although the members of this clade are superficially relatively uniform, closer study reveals that each species is significantly different in lifestyle and behavior from the others, even though they are so similar in appearance that distinguishing some of the species from each other is nearly impossible. And this raises questions. Why do these birds, which behave similarly and feed on the same sorts of food during migration, show such distinct differences in the timing of migration and their passage through Florida? Why are veeries the first to appear, and hermit thrushes the last? What is it about the biology of hermit thrushes that allows them to winter in temperate habitats, while all of the others must return to the tropics each winter?

I’ll never answer these questions, or probably even speculate intelligently about them, but they sure are a lot of fun to think about.

Learning snakes

6 Replies

August 20, 2016

As naturalists, what we observe and learn is directly connected to how we look. I spent more than a decade involved in field and laboratory studies of dusky pigmy rattlesnakes (Sistrurus miliarius barbouri), during which time I had the great fortune to observe thousands of these charming little pit vipers in both natural and captive environments. Still, during all that time studying pigmies, I never witnessed a behavior I was able to watch yesterday morning while road-cruising the forest roads of Ocala National Forest.

Early morning in the scrub with the birds, later with the snakes. Life is good.

An early morning in the scrub of Ocala National Forest, first spending time with the birds, and later with the snakes. Life is good.

Most of my field observations of pigmies in years past took place during systematic group censuses of our primary study population. A group of dedicated snake searchers moved slowly through the hammock habitat, looking for the sometimes abundant pigmies, most of which were individually marked as part of a long-term mark-recapture study. The premium was on finding as many snakes as possible during the census, and measuring characteristics of the found snakes, such as location, substrate, length, weight, and so on. The upside of this approach is you get to see a lot of snakes. The downside is that you don’t get to watch individual snakes very long before you’re on to the next one.

This adult dusky pigmy rattlesnake is in a typical foraging coil.

Not that watching individual snakes is a very productive use of time, in general. Pigmy rattlesnakes normally don’t do much most of the time. They are classic ambush predators, and will sometimes remain in a foraging coil without moving for days at a time. The majority of snakes found are coiled and waiting for some unsuspecting frog or lizard to foolishly venture within striking range. The frequency of pigmy rattlesnake movement varies seasonally; in winter and summer months, only 5-10% of snakes found are moving (May et al., 1996). The remaining 90-95% are in foraging coils. The proportion of moving snakes rises to as high as 15% in spring and fall, but at any time of year, most of the snakes that are out and about (as opposed to sheltering under cover) are immobile. So watching a foraging pigmy rattlesnake is, for the most part, a lot like watching paint dry. Observing the snakes that were moving when first seen isn’t much more productive; they are nearly always aware of the human observer’s presence, and when they resume movement, their goal is mostly to get to cover and out of sight.

Pigmy rattlesnakes move relatively infrequently most of the time.

Yesterday morning began not long after sunrise, as I started the first day of data collection for my sabbatical research. The focus of this study is bird behavior, and in particular the effectiveness of different auditory cues in eliciting mobbing responses of passerine birds. Snakes were not the furthest thing from my mind (they rarely are), but I wasn’t thinking as much about snakes as I was about birds. A couple of hours of playback trials occupied me for the early part of the morning, and produced a few cool birds – lots of northern parulas, several prairie and yellow-throated warblers, a couple of FOS ovenbirds, and at least a half-dozen summer tanagers. In addition to the neotropical migrants, year-round residents were in evidence everywhere – lots of Florida scrub jays, including many scruffy gray-headed youngsters, tons of towhees, and frequently heard, infrequently seen white-eyed vireos. By 9:45 or so it was hot enough that bird activity was on the wane, so I gave up the structured protocol of research and switched to random road-cruising fun.

Yellow-throated vireo and yellow-throated warbler, traveling together in the scrub. Mixed-species flocks consisting of up to a dozen species are the basic functional unit of mobbing behavior.

A couple of distant, rapidly moving black racers were the only snakes I found crossing Forest Road 33; at about 10:30 I headed east on FR 46 towards its intersection with SR19, and then home. It was warm enough I didn’t expect to see much bird or other wildlife activity, but I was ready to be pleasantly surprised. I saw a bear on this road around mid-day last fall, so anything is possible.

A scrub lizard, Sceloporus woodi, led me to the baby pigmy, much like the African honeyguide leads people to beehives.

I slowed a bit at the Pat’s Island Trailhead parking lot, and when I did so, I saw a lizard dart from the soft sand at the road’s edge towards cover. He stopped briefly in the open, and I maneuvered my big lens into position to scan the ground for the saurian. I found him, briefly, before he retreated fully into cover and out of sight. It was a male scrub lizard (Sceloporus woodi), a Florida endemic that, though locally abundant, always gets me a little hyped when I get the chance to photograph one. Which this guy refused to give me. But while scanning the ground for the cryptic scelop, I saw something else I would have completely missed with a naked eye view – a neonate pigmy rattlesnake stretched out on the sand and debris. The small size and bright yellow tail identified it as a YOY – a young-of-the-year snake that was almost certainly less than a month old, perhaps no more than a few days old. It still had only the original button that rattlesnakes are born with, meaning it had shed its skin only once (the post-natal shed, which comes 2-4 days after birth and leaves the snake with a single rattle segment). His second shed would add the first interlocking rattle segment below the button, and and would allow this snake to actually rattle, sort of, if it chose to. Which they rarely do. Pigmy rattlesnakes are kind of an embarrassment to the whole notion of rattling.

My first view of the baby pig.

The “rattle” of my baby rattler. No moving parts – he couldn’t rattle if he wanted to. Which he didn’t.

As is typical of pigmies that are detected by a big stinking primate while they are moving, this one had frozen into complete immobility. Such snakes are acutely aware of the sweaty mammal, and usually will remain static and somewhat cryptic for a minute or three; at some point, they apparently decide (?) that the threat is diminished and gone, and they slowly crawl to cover. But this one didn’t do that.

Instead, it began poking its head around the palm frond debris nearby, tongue-flicking occasionally. After a couple of minutes of exploratory behavior, he slowly formed his body into a foraging coil. This process took several minutes, and was completed as the little snake rocked his body back and forth a few times to settle down into the sand. It was of interest to me that when the coil was complete, the yellow-tipped tail wasn’t particularly prominent. Young pigmy rattlesnakes sometimes use their brightly colored tail tip to mimic a small caterpillar or insect larva, wiggling it when frogs or lizards are nearby to entice them into taking a bite. If all works according to plan, the pigmy then takes his bite. The behavior is called caudal luring; the baby pigmy I was watching wasn’t doing it.

Exploratory behavior.

Beginning the coil.

Tighten up.

A rocking little snake.

The final result. Notice that the yellow tail is barely visible from the direction the snake is facing.

A neonate pigmy rattlesnake from Lake Woodruff NWR in a foraging coil, showing a bit of the yellow tail.

So at this point I figured the excitement (!) was over. The baby pig was settled into its foraging coil, and might not move for hours or days. Still I hung around and watched. I was hoping the scrub lizard might make a reappearance, but didn’t really expect any other action from the pigmy. Still, I was pretty happy with what I’d seen so far. In all the years of watching pigmy rattlesnakes in the field, I had never observed one actually form a foraging coil while I watched. The tongue-flicking prior to coiling suggest that chemical cues may be an important part of site selection. Eric Roth showed over a decade ago while working on the pigmy research project that pigmies are more likely to coil and hunt in areas that have been sprayed with frog scent than in nearby similar areas lacking frog odors (Roth et al., 1999).

Pigmy rattlesnakes in some habitats eat a lot of frogs, including both semi-aquatic frogs (leopard frogs, especially) and tree frogs. This a pinewoods tree frog, Hyla femoralis.

I was quite surprised when the little viper began moving his head back and forth a bit, and tongue-flicking. He had been in his coil for less than 5 minutes. When he initially coiled, the spot was in shade, but a moving sun fleck was beginning to encroach on his foraging site. That particular foraging spot would be completely untenable if exposed to full mid-morning sun; the little pigmy would be overheated within minutes.

Moving to a new foraging site. Check out the stick. Good call.

So the little dude did a very reasonable thing – he switched spots. But not very far. He slowly crawled to a still shaded spot less than a foot away, and repeated the behavior. He began nosing at and tongue-flicking around a small twig, and soon settled into a foraging coil situated partially under the stick. The process of forming a coil was much quicker this time. Time stamps from the series of photographs I took reveal that it took him several minutes to form the first coil, but only a little over a minute for the latter.He was still in his second coil when I drove away, but I doubt he stayed there long either. The entire area was soon to be exposed to direct full sun, which would surely require that he relocate again.

Scoping out the new neighborhood.

Beginning to coil.

The second bout of coiling happened much faster than the first.

Coil nearly complete, but the tail is still exposed.

Coil complete, tail hidden. This is how I left him.

Was this baby snake learning how to choose a foraging site? Snakes as a group have never been considered by most biologists to be particularly “intelligent”, whatever that term means. The general view of comparative intelligence among the vertebrates has long been that while birds and mammals are highly intelligent and capable of complex cognitive feats (“learning animals”), the ectothermic vertebrates (fish, amphibians, reptiles) are primarily “reflex animals”, relying mostly on hard-wired, fixed behaviors to respond to environmental challenges. My personal view is that we probably underestimate the cognitive capabilities of most animals. There’s shit going on there we have very limited means of studying and understanding.

Are older pigmy rattlesnakes smarter than younger ones? What is animal intelligence?

From a purely practical standpoint, it seems reasonable that young pigmy rattlesnakes should learn how to choose better foraging sites as they get older. A successful foraging site, particularly one that results in capture and consumption of a prey item, should provide positive reinforcement regarding the characteristics of that foraging site, and the site-selection behavior of that individual should be modified. Actually demonstrating learning by individual animals is a tough nut, though, especially in the field. For learning to have occurred, the snake would have to modify some aspect of its site selection behavior as a result of earlier experiences.

Snakes in the genus Thamnophis (garter and ribbon snakes) have been shown in laboratory studies to learn how to better track prey. This is a peninsula ribbon snake (Thamnophis sauritus sackeni) trying to hang on to an uncooperative leopard frog. Scanned from a transparency.

Demonstrating learning in non-human animals requires controlled conditions and laboratory studies. A quick and dirty Google Scholar search for primary literature on learning in snakes turns up only a handful of citations, some of which show limited modification of behavior based on experience, and others that don’t. Garter snake babies become better at following worm trails with experience, but Richard Shine and his colleagues have shown that Australian black snakes (Pseudechis porphyriacus) don’t learn to avoid toxic cane toads (a novel, non-native prey for these snakes) after encountering them. However, populations exposed to the toads rapidly evolved behavioral avoidance of cane toads, compared to populations with no previous exposure to the toads (Phillips and Shine, 2006). The naïve snakes readily consumed the toads, much to their detriment. This result suggests that toad avoidance in these snakes is an evolved, genetically based behavior.

It would be an extremely premature and foolhardy conclusion to state with any confidence that I had observed a snake learning. None the less, I’m pretty sure that’s what I did.

References

May, P.G., Farrell, T.M., Heulett, S.T., Pilgrim, M.A., Bishop, L.A., Spence, D.J., Rabatsky, A.M., Campbell, M.G., Aycrigg, A.D. and Richardson, W.E., (1996). Seasonal abundance and activity of a rattlesnake (Sistrurus miliarius barbouri) in central Florida. Copeia, pp.389-401.

Roth, E., May, P., & Farrell, T. (1999). Pigmy Rattlesnakes Use Frog-Derived Chemical Cues to Select Foraging Sites. Copeia, 1999(3), 772-774.

Phillips, B. L., & Shine, R. (2006). An invasive species induces rapid adaptive change in a native predator: cane toads and black snakes in Australia.Proceedings of the Royal Society of London B: Biological Sciences,273(1593), 1545-1550.

Cold-blooded mothers

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December 13, 2014

The great artist Haddaway asked “What is love?”; neither the Butabi brothers nor I have come up with a satisfactory answer to that question, but if love is judged by actions, then it is much more widespread among animals than is commonly thought .

I hate the term “cold-blooded” as a descriptor of the thermoregulatory syndrome shown by the majority of animals on the planet, but as a literary device it is quite useful. Cold-blooded as a trope hints at an emotionless, detached demeanor, something that seems a world away from the values associated with motherhood. Some of my recent and less recent experiences with cold-blooded mothers suggest the opposite.

A female lynx spider from mid-August, still fattening up in preparation for producing her cocoon.

Last summer I became entranced with the beauty and behaviors of lynx spiders. Peucetia viridans is one of the first spiders I learned to identify when I moved to Florida (thanks, Craig), and I’ve been aware since then that they are common, widely distributed spiders. But until I began looking for them with more conviction recently, I had no idea of their true abundance. As spider expert Jack Koerner discovered independently, their prowess as predators is prodigious. Not only will they tackle a diverse array of prey, many far exceeding their own body mass, they are also ridiculously abundant in some habitats. As I learned more about them, I began to anticipate the appearance of cocoons and the subsequent maternal behaviors of the females. Jack assured me that they would begin appearing in late September-early October, and he was spot on. I saw my first female guarding her cocoon on October 9, in the Riverside Island tract of Ocala National Forest. After that first sighting, I started seeing them frequently, most often in the head-high inflorescences of dogfennel, Eupatorium capillifolium. On November 1, I found a cluster of 4 females guarding cocoons in a patch of dogfennel at Lake George Conservation Area, and by some coincidence one of them came home with me. I placed her with her cocoon and the top of her home plant on an old tripod, put it on my glassed-in patio, and began waiting.

The first cocoon I saw this fall, October 9, in Ocala National Forest

The lynx mother I adopted, on her first day in the patio. Notice that she is missing her left front leg.

At first I wondered if all of the disturbance, combined with the rather profound change in surroundings (a sunlit successional opening in the scrub to a patio in a suburban subdivision) might cause her to abandon her nest. But I trusted in her instincts, and sure enough, she never moved from her perch astride her cocoon.

A couple of weeks into my wait, I began worrying that the thermal environment I had moved her to would be too cool to allow her eggs to develop at a normal rate. The microhabitat where she had built her nest had direct exposure to the sun for at least a few hours a day; that heat boost must speed up embryological processes. I hoped that the benefits of the sheltered patio might compensate in part for her loss of sun – it probably buffered the temperature extremes she would be exposed to in the open. Perhaps the several hours each night she enjoyed temperatures above those of her natural environment would accelerate the development of her babies somewhat. On November 14, while at Lake George Conservation Area, I visited her home patch to check out the progress of the other females from her cluster. They were all still there; none had hatchlings yet. It was while trying to photograph one under field conditions that I felt a little better about taking my female home; the wind was blowing at about 20mph, air temperature was in the 50’s, and it felt damned cold to me. Further, the females atop their dogfennels were being buffeted back and forth violently by the shifting winds, yet somehow managed to hang on despite what must have been a semi-torpid state. If they were bullriders, they would have all earned eights. It took me about 10 minutes to take even a handful of photos, despite trying to brace and stabilize the dogfennel plants as best I could.

It took me forever to get even one decent image of this mother lynx guarding her cocoon at Lake George Conservation Area. She was being whipped around in every direction by the buffeting winds.

So at home I maintained my vigil, checking every day for the appearance of hatchlings, not even sure exactly what they would look like. Would they be little emerald-green replicas of their mother?

The red widow, Latrodectus bishopi, an endemic of scrub and an augur of good tidings.

On November 30, John Serrao and I did the Ultimate Ocala Loop © looking for whatever animal, vegetable or mineral coolness we could scrounge up. John had a focal animal for the day; he wanted to find a red widow, and that seemed like a cool goal to me, so we stopped on a couple of occasions in palmetto-studded early scrub so John could scour the scrub for spiders. I was astounded when I saw him walking up the road with a palmetto frond, grinning like a hyena. He’d found his widow. I should have seen that as the grand spider omen it was. When we got back to my house, we found that my lynx babies had hatched overnight or early that morning. Big day for the spiders.

Mom with her litter soon on the day of hatching.

Mom with her litter soon after hatching.

For the next two weeks, I had the awesome privilege of watching a master mother at work. On the day I found her newly-hatched babies, I put momma lynx and her tripod-mounted home plant in my backyard garden, in a spot where they would receive at least several hours of direct sun exposure each day. I didn’t really know how long her maternal devotion would last.

The spiderling just below the center of the frame is in the process of shedding its first skin.

Newborn lynx spiderlings

For the first several hours after hatching, her entire brood of 40 or so dapper little spiderlings (mostly orange, not green!) remained within a couple of cm of the cocoon, with mom lurking either directly over them or nearby. Any movement of the dogfennel head or activity near the cocoon would bring her rushing over and posting up in an aggressive stance. I took a bunch of photos, and didn’t realize until I processed the images that some of the spiderlings were already shedding their exoskeletons for the first time.

That’s when I thought of the other cold-blooded mother I’ve had some experience with. Pigmy rattlesnakes. And I began to make comparisons. Pigmy rattlesnake mothers stay with their litter of 2-12 baby rattlesnakes for several days after they give birth to them (most pit vipers give birth to living young rather than laying eggs), which was quite a revelation to me when we were doing pigmy rattlesnake studies back in the 90’s. Not only do they stay near them, they actively defend them against some predators (such as other snakes). Unlike mother lynxes, though, we never saw any sign of aggressive defense by mothers towards big stinking primates. The response of both mother and baby rattlesnakes to the approach of hulking sweaty bipeds was usually to retreat to cover in a fairly leisurely fashion. The mothers were simply choosing the battles they could win; mothers kept in captivity with their young did show an aggressive approach towards a predatory snake (black racer) that was tethered and moved towards the female and her young. (No racers were harmed in the process of provoking these pigmy moms!)

Nearly all pitvipers, and many other snakes, give birth to living young. This is a pigmy rattlesnake birth.

Mother pigmy attending her litter.

Pigmy rattlesnake with her litter

Mother pigmy rattlesnakes maintain their maternal attendance until their babies have shed their natal skin; as soon as they do that, 1-4 days after birth, the kids disperse in all directions, and their association with their mother is over forever. Oh, I suppose they might bump into each other at some point during their subsequent lives, but we found no evidence suggesting the kids periodically return to visit their mother. Or even call.

Once pigmy rattlesnake neonates shed their skin for the first time, they are on their own.

So based on my experience with pigmy motherhood, I thought that perhaps lynx mothers were similar; soon after they hatched and shed, the babies would disperse, and mom would do whatever mother lynxes with empty-nest syndrome do. Which is mostly die. Lynx spiders, unlike pigmy rattlesnakes, reproduce only once, and then die.

I was hoping to actually photograph some baby lynxes ballooning away. Didn’t happen.

Around noon the day after the lynxes hatched, I checked out the dogfennel briefly, and didn’t see mom or any spiderlings near the cocoon. I concluded, prematurely as it turns out, that the babies had all ballooned away and the mother had departed. Many young spiderlings, when ready to disperse from their birth site, climb to the top of a plant when there is a breeze blowing, stick their butts up in the wind and begin releasing silk. When enough silk is out, they release their grip and drift away on their silken balloon. I was pretty pleased at the prospect that all those spiderlings were now safely ensconced in little lynxy hidey-holes scattered around my garden, and that I might see some of them the following spring and follow their growth and maturation.

The next day I decided to do a more thorough search for a lingering baby or two and was surprised and delighted to find the female back atop the plant. As I looked carefully around the dogfennel inflorescence, I found 10-15 babies scattered around the many nooks and crannies of the dogfennel head, now covered with seeds and their pappuses (pappi?). Looking very much like little spiders. Coincidence, Harry Tiebout? It didn’t take long for mom to key in on whatever part of the plant I was focusing on and come rushing over. The next day she was surrounded by 15-20 of her babies, clustered loosely around her again.

Mom with her brood 3 days after hatching

And now here it is, two weeks after birth, and mom is still hanging on. She’s missing a leg, has a patch of white fungus growing on one of her legs (immune system shutting down?), and is moving at an arthritic pace even at mid-day temperatures. Every morning for the last several days I’ve gone out to check on her, expecting to find her dead. Some mornings it’s not easy to tell at first. I can gently prod her and move her legs, and in her early-morning torpid state, it’s hard to tell if there’s any voluntary movement at all. But by mid-morning, after a nice spot of sun, she’s still endeavoring to persevere. Perhaps I should craft her a tiny stove-pipe hat and declare her civilized.

Mom on December 9, down to only a few remaining babies still at home. Still defensive, but slowing.

Sticking close to mom.

Catching the last bit of sun in the afternoon. Wonder if she feels as arthritic as she looks?

Yesterday, I thoroughly inspected the plant with a visor magnifier, and found only one baby remaining. On mom. For whatever it’s worth, a more devoted and persistent mother than the more “advanced” pigmy rattlesnake. The baby lynx stayed on his mother’s emaciated abdomen for several minutes while I photographed them, and then rappelled on a silken dragline to a seed cluster below. Mom moved achingly slowly to the top of the plant to bask. Would this be her last sunset?

One more morning.

Ravaged by starvation, fungus, and who knows what other maladies, she soldiers on.

Hanging with mom.

Just 15 minutes ago, I could find no baby lynxes other than one tiny mummified little corpse. But mom is still there.

Yesterday afternoon. No more than a few days left for her at most. I’ll miss her.

Does a mother pigmy rattlesnake or lynx spider love her babies?

What is love?

Postscript, December 21:

She was tougher than I gave her credit for. She was dead this morning, over a week after the last of her offspring had dispersed.

References:

Greene, H. W., May, P. G., Hardy, D. L., Sciturro, J. M., & Farrell, T. M. (2002). Parental behavior by vipers. Biology of the Vipers, 179-205.

Caniphilia

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October 18, 2014

I don’t think it’s really necessary to coin this term; the love of dogs is a fundamental human condition. I wouldn’t trust a man who dislikes dogs as far as I could throw him. Such an inability to form a connection with these magnificent animals with whom we share a long coevolutionary history indicates a very basic flaw in character and humanity. To any dog-haters who might happen to read this, I have this advice. Seek treatment for your affliction. Try to make yourself a better human being.

Dogs are the original GMO, or genetically modified organism. As William Sanderson’s wonderful character in Blade Runner, B.F. Sebastian said, speaking of his robotic humanoid toys, “They’re my friends. I made them.” Dogs are our friends. We made them.

J.F. Sebastian, with Pris and one of his friends.

In contrast to modern GMO’s, which are largely created by copying and pasting specific genes from one organism to another, dogs were built the old-fashioned way, over thousands of generations of artificial selection. Although the mechanism by which dogs first became domesticated is not entirely clear, the process began at least 15,000 years ago, and perhaps far more. DNA sequencing evidence strongly suggests that wolves were the progenitors of the domestic dog, and the first steps towards domestication may have occurred when humans adopted wolf pups and socialized them to accept human companionship, or it may have been more of a “self-domestication” process in which some wolves began associating with humans for food, protection, and perhaps other benefits. Since those earliest proto-dogs, selective breeding by humans (artificial selection) has produced an entirely new animal, recognized as a separate species from the gray wolf (though dogs and wolves readily hybridize, as do other members of the genus Canis, including coyotes).

A recent paper in the journal Genetics (Wilkins et al. 2014) presents a fascinating story about the interaction between genes, embryological processes, and evolutionary change and how these processes have produced many of the differences seen between dogs and their canid ancestors. Dogs, like many domesticated mammals, show a suite of traits that seem to commonly arise during domestication. Aptly dubbed “domestication syndrome”, these traits include reduced fear and anxiety around humans (tameness), as well as physical traits like changes in color patterns, droopy ears and tails, reduced brain and skull size, and smaller teeth. Why do all of those traits tend to occur together in domesticated animals, when it is primarily the tameness that is being selected for in their interactions with humans?

From Wilkins et al., 2014.

According to Wilkins et al., the phenomenon of tameness is one of many traits linked to a remarkable group of cells, found only in vertebrates and their closest relatives (tunicates), that are active in early embryological development. These cells, called neural crest cells, originally form and differentiate as part of the developing nervous system during the process called neurulation. But rather than stay with the central nervous system to form the brain and spinal cord, as most of the cells formed during neurulation do, neural crest cells are wanderers. They break away from the developing spinal cord and travel throughout the body to take up residence in a wide variety of developing tissues and organs, and differentiate into a dizzying diversity of tissues and organs. Some move into the skin, where they form the pigment-producing cells called melanocytes. Others are involved in formation of cartilages in the ears, while other neural crest cells form one of the types of cells that build teeth, the odontoblasts. Others contribute to bones of the skull, while yet other neural crest cells become neurons and ganglia of the peripheral nervous system. Most importantly with regard to domestication, neural crest cells are involved in development of the adrenal glands and other components of the sympathetic nervous system, which produces the so-called “flight or fight response” when vertebrates are placed in physically or emotionally challenging situations.

According to the Wilkins et al. model, domestication first began genetically modifying dog ancestors by selectively favoring those individuals that showed reduced stress response around humans, due to a less intense “fight or flight response”. These were individual wolves that had experienced reduced neural crest activity during development, and a somewhat underdeveloped adrenal gland/sympathetic nervous system response. Such variability in genetically encoded traits is a prerequisite for natural or artificial selection to occur, and is widespread.

But because neural crest cells are involved in so many other developmental events, selection for reduced neural crest activity (“mild neurocristopathy”, as they called it) also resulted in evolution of other traits, including floppy ears and droopy tails (reduction in cartilage-producing tissues), color patterns (reduced melanocyte activity), smaller teeth (reduced odontoblast activity), and smaller skulls and brains. Though only “tameness” was being directly favored by their association with humans, changes in physical traits transpired due to the selection for reduced neural crest cell activity. This is, to me, a truly elegant hypothesis, which emphasizes the ease with which minor changes in developmental pathways can lead to major evolutionary changes in body form and function of the adult organism.

Luna, indisputably the greatest dog who ever lived

Regardless of how dogs got to be dogs, the result is an animal with which we are inextricably linked in our evolutionary meanderings. And it is completely natural to love them. The only dog I’ve ever had that belonged only to me was a little mixed-breed husky mix named Luna, and I loved that dog in ways that I never knew were possible. When I had her put to sleep in 2006, I was inconsolable for months. I’m not ashamed to say that for weeks after she died, I would find myself at times sobbing uncontrollably over the loss. I still get a little misty-eyed sometimes when I look at old pictures of her.

If I saw mammals like this Sigmodon hispidus more often, I’d probably like them better. But I don’t.

Truth be told, I’m actually not all that enamored of most mammals – they are largely nocturnal, not particularly colorful, and often difficult to observe, all traits in direct contrast to some of my truly favorite taxa such as birds, butterflies, odonates, and flowering plants. But I make an exception for carnivores, and particularly canids. Nothing excites me as much as seeing a wild dog. Coyotes are absolutely enchanting animals. God’s dog, as they have sometimes been called, are beautiful, wicked smart, adaptable, and at times quite mischievous, to put it mildly.

I had been living in Florida for over a decade before I saw my first coyote. I still have a vivid memory of driving north on Lake Winona Road in 1991 or 1992, through mixed sandhills, hammocks, and agricultural habitat and seeing a doglike animal crossing the road a couple hundred yards ahead of me. As it reached the edge of the road, it paused broadside and looked directly at me for a few seconds before disappearing. No more than a 15-second observation, if that, but I knew instantly it was a coyote. The lope, the elegant profile, big ears – all screamed coyote. I was entranced. It took several years before I saw another, this one only briefly again as it darted across Dark Entry Road in Tiger Bay State Forest.

In the last several years, though, I’ve been seeing coyotes much more regularly. Maybe because I’m getting a little better at spotting them, maybe because they are increasing in numbers. Probably some of both. I sure hope at least the latter is true. For one thing, more coyotes means fewer feral and free-ranging cats. And that’s a good thing. When human activity first begins modifying the ecological systems in a developing area, top predators are usually the first component to disappear. It gives me a bit of hope to see them increasing on their own, despite widespread prejudice and wanton slaughter of these beautiful dogs. Over 75,000 coyotes were killed in 2013 alone by the USDA’s Wildlife Services, along with many other top predators. (Thanks to Mia McPherson and her wonderful blog On The Wing Photography for that disturbing statistic.) Yet they continue to prosper.

I’m still waiting for my first decent photo opportunity with coyotes. In 2011, I watched one circling a herd of cattle, including a small calf, looking very much like a border collie working a flock, from State Road 42 in Lake County. For a minute or two, the coyote stayed in view, frequently veering back and forth as it scoped out the big slobbering bovines. Quite distant, but my first coyote photos. In 2012, I was driving through Heart Island Conservation Area near mid-day in August, and saw a pair of half-grown coyote pups trotting down Deep Creek Road in front of me, occasionally slowing to give me a sidelong glance. More recently, I had direct eye contact for a fleeting but electrifying moment as I drove by one in Ocala National Forest, on SR19 just south of Silver Glen Springs. He had crossed the road in front of me and paused briefly to look back from the dense thicket perhaps 50 feet away. This year I’ve seen single coyotes a couple of times at Lake George Conservation Area, and a month or so ago crossing Rima Ridge Road in Tiger Bay State Forest, near the Bennett’s Field primitive campground. But I still haven’t been close enough to one in decent light to get true coyote photos (as opposed to photos with a coyote somewhere in them). But I always assumed that the first wild canid I photographed in Florida would be a coyote.

Stalking coyote.

This one might be doable, he’s thinking.

Coyote pups at Heart Island Conservation Area.

In Tiger Bay State Forest

How wrong I was. On September 21, I was cruising north on Paisley Road through Ocala National Forest, perhaps a half-hour after sunrise. As I rounded a bend near a big seasonal wetland called Mud Lake, I saw two quadrupeds in the road several hundred yards away. My first thought was coyotes, but they were small and delicate looking. Gray foxes! I’ve probably seen gray foxes in Florida less than 5 times in the 30+ years I’ve lived here. Knowing with absolute certainty that they would be gone as soon as I slowed down, I pulled sharply to the right and grabbed my camera with the 150-500 Sigma zoom and slowly moved it up and onto the beanbag on my car window. And of course both foxes had darted into the thick patch of Bidens (alba, CB!) at the road’s edge. But after a moment one came back out. She trotted back across the road, turned around, and then spent a half-minute or so dawdling in the road. I took a distant shot, but it would be marginal at best. Still, a gray fox. Starting the engine and attempting to slowly stalk her in the car seemed a pretty vain course of action.

Paisley Road, Ocala National Forest

My first view of the gray foxes. Hard crop.

Then I recalled a conversation I had recently had with my friend John Serrao, when we had been on one of our field jaunts. I think we had seen a bobcat or a coyote briefly, and John told me of several experiences he had with predators while living in in Pennsylvania. He told me had been able to call in a variety of predators by making squeaky noises with his lips, much like the squeaky noises birders sometimes make to attract dicky birds. He once had a weasel walk across his shoe, he told me, as he stood absolutely still and made the squeaking noises. Very soon after that conversation, I searched on-line and found several .mp3 files of rodent distress calls, which I added to my Ipod library, thinking I’d probably never use them.

Urocyon cinereoa_09212014-23_Ocala NF FR69

Maintaining contact with her mate, out of view in the roadside vegetation.

But in fact I did use them. As the fox frolicked in the road far away from me, I played one of the tracks titled “Squealy”, a series of high-pitched shrieks from some rodent or hare, through my car stereo. The effect on the vixen was immediate, and thrilling to me. First she looked directly at me, ears erect, clearly focusing on the sounds. And then she came closer. And closer. And closer. She criss-crossed the road repeatedly, veering from one margin to the other, approaching me in a series of diagonal trots, all the while focused on me, trying to fire off frames without making any obvious movement. On several occasions she stopped and faced towards the thick vegetation beside the road that her running mate had gone into – I suspect he was paralleling her as she neared me, but staying out of sight in the vegetation. Once or twice she stopped, squatted, and apparently peed briefly. Mostly as she covered the substantial distance between us she was in the shade, but on a couple of occasions she passed through pillars of low-angle sunlight streaming in through small gaps in the roadside vegetation. The combination of the exquisite delicate beauty of the vixen and the rich, warm early-morning light nearly made me delirious with joy. When she made her final veer and crossed the road no more than 50’ in front of me disappearing into the brush, I was as high as a kite on adrenaline and whatnot.

In the light pillar.

And still she came.

Girl’s got to pee when a girl’s got to pee.

A few moments after she had disappeared and I began to come down a bit from my reverential high, I realized I had photographed the entire sequence with the OS (optical stabilization, a vibration-reduction system to reduce camera movement and improve image sharpness) on my big telephoto lens OFF. Momentary panic followed as I envisioned all of the shots being uselessly blurred due to the slow shutter speeds I was forced to use in the early morning light. A couple of minutes spent “chimping” the hundred or so images I had taken on the camera’s display calmed my fear a bit – perhaps not as sharp as they could have been, but at least a couple were acceptable.

Urocyon cinereoa_09212014-53_Ocala NF FR69

Still checking the road margins for the shier male.

Back and forth she came.

The final veer. The eye contact was amazing.

Last usable shot in the sequence.

It was a once-in-a-lifetime privilege for me to watch and photograph this charming wild dog, if only for a few minutes. For the life of me I can’t understand the mindset of those who wish to kill these and other top predators on general principle.

Coyotes are next. It can’t happen too soon.

Acknowledgements: Thanks to Gene Spears, or Gene Gene the Dancing Machine as he was known in grad school days, for turning me on to the Wilkins et al. paper.

References:

Wilkins AS, Wrangham, RW and Fitch WT (2014) The “Domestication Syndrome” in Mammals: A Unified Explanation Based on Neural Crest Cell Behavior and Genetics. Genetics 197(3):795-808.

Shameful shit

2 Replies

May 18, 2014

I have no words to fully express my shock and profound sadness on finding this magnificent animal, head and neck crushed by a cretinous driver, in Ocala National Forest yesterday. I’ve been fantasizing about photo ops of an EDB crossing a forest road for several years now; this was not the picture I had envisioned. We watched with disgust and disbelief as he slowly writhed and tried to gape while the last spark faded from his defiant eyes.

Crotalus ad DOR_05172014-08_Ocala NF FR05

A 4′, heavy-bodied healthy eastern diamondback crossing a pale sand road in Ocala National Forest. This animal was run over intentionally.

What kind of deeply depraved mindset does it take for someone to do this?

Some of my Facebook friends captured some of the thoughts that occurred to me, and some that didn’t.

“Damn, Peter, that ruined my day. People suck. Some people suck.” – John Jett

Ours too, JJ.

“Only someone unhappy would do this.” – Mary Ohlman Shaperow

Unhappy and morally retarded, Mary.

“The real issue, is that it’s really hard to change people’s minds on this, it is really, really entrenched in so many…just ignorance multiplied and taught to others.” – Chris Kincaid

Education is one answer, Chris. But it’s futile when dealing with closed minds.

“Oh man, I hate hate hate hate hate to see this. I’m preaching to the choir here, but I truly can’t understand how/why so many people aren’t able or willing to respect this amazing (and very important) species.” – Janson Jones

Keep preaching, Janson. You make a difference.

“That is FUCKED UP. Period.” – Patrick McGowan

Right on, Patrick. Right on.

Why no sparrows?

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Sunrise in the scrub. Forest Road 46, Ocala National Forest

May 10, 2014

I find being in big expanses of native habitat around sunrise has the effect of producing brief moments of clear-headed thinking. For me, this is especially true of the more open habitats, like early stage scrub, where you can easily track the incremental effects of the ascending sun as the surging morning light progressively highlights newly visible features of the environment. I was sitting in just such a dense patch of oaky scrub in the Juniper Prairie Wilderness area of Ocala National Forest on Wednesday when one of those rare moments of lucidity raced through my normally muddled brain. I kid you not that I was actually sipping my tea when I heard the clear whistle and trill of drink-your-tea coming from the dense scrub. At that moment, I realized that I had made a foolish and easily refutable claim in my last post, in which I pondered the absence of breeding sparrows in most Florida habitats. I claimed that for the most part Bachman’s sparrow was the only breeding species in most inland or upland habitats of the Florida peninsula.

As it turns out, Bachman’s sparrow isn’t the only widespread breeding sparrow in the Florida peninsula.

Astute birders and natural historians no doubt immediately recognized the fallacy of that statement – there’s one species of sparrow that breeds in a variety of habitats in peninsular Florida, and can be incredibly abundant in some, including scrub. Towhees are sparrows, really. We just don’t call them sparrows. A bit larger and more conspicuous in plumage than the typical cryptically-hued sparrow-type sparrows, but members of the same family (Emberizidae) nonetheless, and classified within that family as belonging to the same clade as the New World sparrows. In most respects, their ecology is similar to that of the smaller sparrows – they are omnivores, feeding more on seeds and plant-derived foods during the fall and winter, and switching to more of an animal-based diet during the breeding season when their voracious offspring need more protein than is available in most plant foods. They are fond of open or early successional habitats, though in Florida they nest in open-canopy woodlands like flatwoods or scrub as well. Eastern towhees were by far the most common breeding birds I heard in most areas of the Juniper Prairie Wilderness scrub on this beautiful May morning.

Drink your tea, he said. I was way ahead of him.

The juvenal plumage of eastern towhees clearly shows their affinity to sparrows.

So we do have a common breeding sparrow in many peninsular Florida habitats. But that doesn’t really resolve the conundrum – in some ways it magnifies it. If this one species of emberizid can successfully maintain viable populations here, why not the other sparrows with which it frequently co-occurs in breeding bird communities further north? It’s not hard to find towhees nesting along with other species typical of the shrub-sapling stage of old field succession, such as song and field sparrows. The enigma is further confounded by the fact that field, song, grasshopper, chipping, swamp, and several other rarer sparrows (Henslow’s, LeConte’s, Lincoln’s) can be found wintering in these habitats in Florida. But none stay to breed. Why not?

Field sparrows winter in peninsular Florida, but don’t stay to breed here.

The sparrow problem is just one component of the riddle of peninsular Florida’s low breeding bird diversity. One of the most well-documented trends in landscape ecology is the profound latitudinal gradient in species diversity among a wide range of taxa – as you move from the temperate zones towards the tropics, the number of species of many, many groups of organisms increases dramatically. Though this pattern is widely known, it hasn’t been clearly explained in terms of an underlying cause or mechanism. More than a dozen hypotheses have been suggested to explain the higher diversity in the tropics, but none is universally accepted, and in fact most of the hypotheses are not even mutually exclusive. Like many complex ecological phenomena, the origin of these diversity gradients is probably multifactorial, arising from a number of interacting factors and causes. Higher productivity, greater climatic stability, a longer evolutionary history, greater importance of biotic interactions such as competition, predation, and parasitism – all of these and many more may contribute to the higher tropical diversity. But despite the fact that Florida is at a lower latitude than most of North America, and might therefore be expected to have higher bird diversity than areas further north, at least for breeding species of land birds that isn’t true. The picture with respect to breeding bird diversity in eastern North America is more complex and perplexing.

Number of breeding land bird species in North America, from a paper by Cook (1969).

The figure above, originally published in a 1969 Systematic Biology paper by R.E. Cook, contains a wealth of head-scratching trends in diversity. I first saw this figure in Eric Pianka’s classic little book Evolutionary Ecology over 30 years ago, I think, and it has taunted me ever since. This map shows the number of breeding land bird species in 300-square mile blocks, and even at this crude level of resolution, the contradictions and puzzles are enough to make me swoon. If you focus on the numbers of species breeding in the middle of the continent, starting in the prairie provinces of Canada and working towards Mexico and Central America, the temperate-tropical diversity gradient is apparent. But to the east, something funky is going on. Diversity actually is greatest at higher latitudes. In particular, notice the column of blocks that includes Florida – there are 141 breeding species in the region of the Great Lakes, but in the southeast block that includes Georgia and North Florida, there are only 93 breeding species. Though there is no number for the block that contains peninsular Florida, by my reckoning that number is about 72. I’ll repeat my previous claim – breeding bird diversity of land birds in the Florida peninsula is abysmal relative to the rest of eastern North America.

The reduced numbers of species of some taxa in Florida has been explained at times by the so-called peninsula effect. For a variety of types of organisms, peninsulas often show reversed diversity gradients from base to tip, though the mechanism for this trend is difficult to pin down. One component for some organisms may have to do with the colonization and extinction dynamics of populations in the peninsula (I’m referring here to extinction of individual populations in an area, not an entire species). Because peninsulas have less direct connectivity with nearby land areas that may serve as a source of colonizing organisms, they may lack populations of species with poor vagility that are unable or unlikely to reach the more distant parts of the peninsula. Further, smaller extents of appropriate habitats in peninsulas may support smaller populations of the organisms that do manage to colonize, producing higher extinction rates for these populations. Finally, the range of habitat types may be reduced in peninsulas, preventing some species from colonizing in the first place. With respect to birds, the colonization argument just doesn’t work. Many of the bird species whose absence as breeding birds puzzles me migrate through or winter in the peninsula in large numbers, so getting here isn’t the problem. The population size and habitat availability arguments may contribute to Florida’s low breeding bird diversity, but they aren’t the whole story.

Northern parulas are abundant foliage-gleaners of hammock habitats, but other warblers and foliage-gleaners typical of forest habitats further north are absent.

For both islands and peninsulas, greater land area is related to greater species diversity, called the species-area effect. That may explain some of Florida’s lower breeding diversity, but not all of it. Look at the number of breeding bird species in the block that includes that little sliver of land called the Isthmus of Panama – it has around 600 breeding species! Land area isn’t everything.

One of the problems with the peninsular effect as an explanation for Florida’s low diversity of breeding birds is that this reversed diversity gradient of breeding birds isn’t restricted to the Florida peninsula – it is general to the southeastern United States. But even so, many bird species common as breeders in the southeast don’t make it into the peninsula. There’s something else going on here. One of the proposed explanations for reduced densities and diversity of breeding land birds in the southeast is related to the dynamics of primary productivity in temperate habitats. Simply put, temperate habitats further north experience a much more concentrated burst of plant growth in spring as all of the dormant vegetation begins leafing out around the same time, providing huge amounts of tender nutritious leaf material for herbivorous invertebrates. This burst of productivity works its way up the food web, resulting in a glut of food for the breeding birds. Spring certainly brings a burst of new growth in Florida, but probably not as dramatic and concentrated in time as in more northerly habitats. One factor contributing to this reversed diversity gradient among forest bird communities of eastern North America, which benefit hugely from this spring burst of productivity, is that more northerly bird communities show show both decreased extinction rates of individual species in the community, and lower turnover rates in community composition (number of species that disappear or appear between years). Stated another way, more southerly populations of these forest-breeding birds are more likely to disappear over time, and more likely to be replaced by other species.

Red-eyed vireos are far more abundant in migration than as breeders in peninsular Florida

The breeding bird communities of peninsular Florida’s broad-leaved forest habitats (hammocks) have always struck me as being particularly depauperate. Northern parulas are usually abundant, but other species of foliage-gleaning warblers are hard to find. There are no ground-foraging forest warblers breeding here at all, though ovenbirds are common in migration in these habitats. Red-eyed vireos, one of the most abundant breeding species of eastern deciduous forest, are present as breeders in many Florida hammocks, but at much lower densities than further north. It seems to me that both the productivity burst effect and area effects may be at work here. Many of the characteristic tree species of hammocks are evergreen; even though these species do put out new foliage in the spring in a leaf flush (live oaks, for example), the boom-bust nature of the resource experienced by birds breeding in forest habitats further north is not as dramatic here. In addition, hammocks themselves tend to be more patchily distributed and limited in area than do deciduous forest tracts in eastern North America. Smaller extents of habitat support smaller populations, which are more likely to go locally extinct, and exclude wide-ranging species that need large expanses of appropriate habitat in order to maintain viable populations. Hammock habitats in the peninsula are actually probably far more extensive now than they were historically; fire suppression in some formerly extensive habitats has resulted in expansion of fire-intolerant hammock habitats in many areas that once supported vast tracts of fire-dependent plant communities like sandhills and scrub.

Hammocks are historically patchily distributed habitats in peninsular Florida, but have expanded greatly due to fire suppression.

Other forest breeding guilds (a guild is a group of species that use similar resources in a comparable way) besides the foliage-gleaning warblers and vireos are equally perplexing. Tyrannid flycatchers, for example. Eastern deciduous forests further north typically support several species of forest-breeding flycatchers, including great crested flycatchers, eastern wood pewees, and Acadian flycatchers. We have lots of great cresteds, but Acadian flycatchers and pewees become harder and harder to find the further south you go in the peninsula. It’s tempting to suggest competition with insects as a possible link to the lowered diversity of breeding flycatchers in Florida – the superabundant and diverse dragonfly community must to some degree reduce the resource base, flying insects, on which tyrannids depend.

Do dragonflies, which presumably compete with flycatchers for aerial prey, reduce diversity and density of tyrannids in Florida?

Great crested flycatchers are common breeding birds in Florida, despite any competition from odonates.

Other forest tyrannids, like this Acadian flycatcher, are scarce as breeders.

But none of those explanations seem to fit the sparrows. Most sparrow species in eastern North America are characteristic of disturbed or successional habitats – song, chipping, field, grasshopper, and so on. Successional or disturbed habitats by their nature are patchy in distribution, often limited in areal extent, and prone to disappearance over time as they are replaced during the process of secondary succession. Superficially, an old-field habitat in Florida is remarkably similar to one in Virginia, except that breeding bird diversity and density is dramatically lower. Examine the breeding density maps prepared by the U.S. Fish and Wildlife Service (http://www.mbr-pwrc.usgs.gov/bbs/bbs.html) for any of the missing Florida breeders. I’ve pasted these breeding density maps below for four species: song sparrow, field sparrow, chipping sparrow, and eastern towhee. The low breeding abundance or complete absence in peninsular Florida of the three “typical” sparrows is apparent, and in marked contrast to that of the towhee, which actually shows increased breeding abundance in the central-southern portion of the Florida peninsula.

Song sparrow, a common winter resident that doesn’t breed in Florida

Song sparrow breeding abundance

Field sparrow

Field sparrow breeding density

Chipping sparrow

Chipping sparrow breeding density

Does the smaller burst of insect productivity in spring prevent species like this field sparrow from successfully raising young here?

Florida race of the eastern towhee, Pipilo erythropthalmus alleni.

Breeding density of eastern towhees. Why are they so much more successful in the southeast than other sparrows?

So towhees love Florida, even though the productivity burst model may affect Florida towhees to some degree as well. Eastern towhees in Florida show the same shift in diet between winter and spring as do more northerly populations; they switch from a greater reliance on plant-based foods in the winter to more animal prey in the spring and summer. However, the magnitude of the shift is of a lesser magnitude in Florida towhees, who rely more on plant-based foods during the breeding season than do northern populations, perhaps hinting at a lower availability of insects in the Florida habitats used by towhees as well.

But what is it about towhees that makes them so successful in Florida, while all the other sparrows of similar habitats hightail it north in the spring? I’m still awaiting enlightenment.

Reference: Cook, R.E. 1969. Variation in Species Density of North American Birds. Systematic Biology 18 (1): 63-84.

Lekking in DeLeon Springs

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March 8, 2014

To me, one of the most amazing achievements in field ornithology and bird photography of the last decade or two is the bird of paradise project, sponsored by the Cornell Laboratory of Ornithology. During the 8 years of this project, evolutionary ecologist Ed Scholes and biologist/photographer Tim Laman travelled 18 times to New Guinea, the center of diversity of these magnificent birds, to document and film the courtship behavior of all 39 species comprising the family Paradisaeidae. Ever since I obtained Cooper and Forshaw’s stunning 1977 masterpiece, The Birds of Paradise and Bower Birds, and spent hours poring over its oversized plates depicting their lavish colors and hypertrophied plumage, I’ve been in love with these birds. Outrageous sexual dimorphism and bizarre courtship behaviors, along with their exotic locale, made these birds seem otherworldly and alien to me. And they might as well be on another planet – I’ll never see one in the flesh. But I’ve seen something nearly as enchanting and mystical, in a residential neighborhood in lovely DeLeon Springs.

Tuesday morning began as most mornings this winter have. Despite forecasts of clearing skies and warming temperatures by mid-morning, it was a gray, cold, misty morning when John Serrao and I left for a birding cruise through Ocala National Forest. We had faint hopes that the warming temps might even produce a herp or two crossing the roads, but that was a fantasy. The dismal, dreary weather and dull light persisted throughout the morning. But we saw birds – lots of warblers and other wintering/migrant passerines were active, including some of the largest flocks of yellow-rumped warblers I’ve seen this season. As I’ve noticed on several other occasions over the last several weeks, many of the yellow-rumps were feeding on the ground, sometimes in the road, often along with palm warblers and chipping sparrows. Yellow-rumped warblers have one of the largest repertoires of feeding behaviors of any of the parulids; I wonder how this is related to their overwhelming abundance and wide range of habitats they use.

Yellow-rumped warblers are mainly foliage-gleaners, but will also feed on the ground, engage in flycatching, and feed on fruits and seeds at times

Despite the less than ideal weather, we actually managed to see a reasonable number of cool birds, including yellow-throated, orange-crowned, palm and pine warblers, ovenbirds, singing northern parulas, blue-headed vireos, hermit thrushes, ruby-crowned kinglets (occasionally displaying the full red crest to each other – just one more indication that testosterone levels are on the rise), Florida scrub jays, and so on. A thoroughly enjoyable morning, but mostly lacking in photo opportunities.

Despite the weather, singing northern parulas were one more bit of evidence that Spring is actually here.

Ruby-crowned kinglets are showing their red crests more often these days. They just won’t do it for me when a camera is aimed at them.

Most passerines were sticking close to cover and concentrating on feeding. This hermit thrush was a welcome exception.

As small, energy-limited passerines often do on cold or inclement days, most of the birds we saw were fixedly engaged in feeding. Maintaining or building up fat reserves seems to take precedence over most other activities on days like these. Response to pishing and playback was brief and minimal. We did lots of looking, relatively little shooting.

Scavenging bald eagle in the scrub

The best photo op we had in the forest was a nearly mature bald eagle feeding on roadkill raccoon on the shoulder of US19, along with a flock of black and turkey vultures. The eagle flew up into a lichen-covered oak skeleton as we approached, but gave us extended looks for several minutes, as cars and trucks zipped by.

Part of the DeLeon Springs peacock flock

The trip home produced our most memorable sighting of the day. There is a neighborhood in DeLeon Springs I often drive through when going to Woodruff or other locations north of DeLand that is home to one of the largest flocks of Indian peacocks I’ve seen. At times more than a dozen birds can be found in one small yard. That’s quite an impressive spectacle at any time of year. On Tuesday, we witnessed what is probably a common sight to those used to living with peacocks, but which I had never seen in its entirety – the full display of a peacock in peak breeding plumage. Absolutely mind-blowing. Charles Darwin once wrote that the “sight of a feather in a peacock’s tail, whenever I gaze at it, makes me sick!”, because he couldn’t fathom how natural selection could have produced such an overblown, seemingly useless adornment. It led him to develop his principle of sexual selection, hypothesizing that extravagant features such as the peacock’s tail have evolved in response to females’ preference to mate with males that have the most striking accoutrements. Evolutionary biologists have embraced Darwin’s principle of sexual selection, but still argue over the specifics of the mechanism. Why would females choose to mate preferentially with the most gaudy males?

Indian peacock (Pavo cristatus)

And what a gaudy display it is – I had seen males in low level display before, fanning the ocellus-adorned plumes of their tail feathers. I was surprised to learn that the prominent plumes with the startling ocelli (eyespots) are not true tail feathers (rectrices) at all – they are highly modified upper tail covert feathers, like the yellow feathers on the rump of a yellow-rumped warbler. But I had never seen the full display, which is prolonged, graded, and complex. It begins with a slight spreading and elevation of the train, but progresses to a towering display in which the train is held perpendicularly over the back. At its peak, the male quivers the train for several seconds in what seemed to me to be an almost orgasmic burst of pride. It reminded me a bit of this classic Saturday Night Live skit. As females walked by, paying no attention whatsoever to the displaying male, he slowly rotated to track their passage and show his erect train to best advantage.

The true tail feathers (rectrices) can be seen here behind the plumes, which are really upper tail coverts.

A moderate-intensity display.

A high-intensity display. The train is held perpendicularly over the back, and the male quivers the plumes for a second or two. The female ignored his efforts.

Not surprisingly, Indian peacocks have a polygynous breeding system, like many of the most spectacularly dimorphic birds or paradise. In these systems, males contribute nothing to reproduction other than their sperm. In the wild, females choose among several available males who display simultaneously in an arena-like location called a lek. In some lekking species, the male that occupies the central, preferred location in the lek obtains nearly all of the matings with sexually receptive females. Clearly, in such systems it is a great advantage to be a little gaudier than nearby males.

Full display.

Because males in these polygynous species have been freed of all parental duties and investments other than contributing a set of chromosomes (and centrioles), they often evolve spectacular plumages and displays to advertise the quality of their genes. That, presumably, is why females select the gaudiest males. Only males of superior genetic quality can afford to invest the time and energy in producing these extravagant displays, and by mating selectively with the showiest males, females ensure their offspring will be of high genetic quality. Further, their sons will inherit the genes for these high-quality displays, and are more likely to be successful as sires once they are mature.

What female could resist this gorgeous male? In fact, they all did. Maybe persistence is the key.

Anyway, that’s the way the system is supposed to work. Studies of mate selection by Indian peahens (the female of the species; only the male is a peacock) have produced mixed results. Some studies have shown that females do seem to prefer males with their full complement of ocelli over manipulated males whose ocelli have been selectively trimmed, but there also seems to be relatively little variation in the number of ocelli among unmanipulated male birds. There is no evidence that females prefer males with longer trains, even though train length is correlated with the diversity of MHC (major histocompatibility complex) genes in males. A seven-year study of peafowl in Japan showed that train characteristics played no part in female choice of mates, and further, that the extravagance of a male’s train was not correlated with other measures of his physical condition.

As is often the case, the reality of nature is more complex and perplexing than our simplistic models and hypotheses suggest.

The Ultimate Ocala Loop

January 26, 2014

I’m always on the lookout for new birding loops. I do a lot of my birding by road-cruising. All other things being equal, I prefer to get out of the car and into the habitat. Unfortunately Florida habitats, like those in every other part of the world where I’ve birded, are not particularly welcoming to my people. So from a purely practical consideration, I can cover vastly more area and see more stuff by car than by my limited means of self-propulsion. Natural areas with extensive hard-packed trails are always a treat, but I’ve found that the more accessible a natural area is, the more heavily visited it is. Profound. I prefer my natural history outings to be populated mainly or entirely by folks I choose to be with. Which is often no one. Some might call me a misanthrope. I hate those people.

When birding by car, the ideal trip for me is a big circuit that satisfies several requirements: a) it involves little or no time driving on heavily traveled roads that are impractical for slowing, stopping or wildlife observation or photography, b) it includes as wide a variety of interesting habitats as possible, c) the good light for photography is on the driver’s side as much as possible, and d) it is centered on DeLand and can be completed in a half-day or so. Finding new loops that meet these criteria is always a big rush.

So armed with a sense of adventure and optimism, I tried a new loop yesterday, and I’m pleased to report that it is the ultimate driving loop for birding Ocala National Forest. That’s a pretty presumptuous claim given the hundreds of miles of drivable roads in Ocala, so I should probably qualify it by saying merely that it is the ultimate Ocala driving loop that I’ve experienced to date. Anyway, I was recently accused of being “full of crap” by one of the most accomplished blowhards and bullshitters I’ve ever known; if you buy the premise that nobody can spot a bullshitter like another bullshitter, then my credibility is pretty low to begin with. Making one more extravagant and insupportable claim probably won’t adversely affect whatever shred of credence I might have.

Paisley sunrise looking south towards Lake Akron

Paisley sunrise looking southeast towards Lake Akron

I left home about a half-hour before sunrise Saturday morning and drove west on 44 across the St. Johns River, heading for the southern edge of the forest, whose boundary is formed by State Road 42. I was hoping to hit Paisley just as the sun was rising; a big successional field slopes downwards towards Lake Akron just before you enter Paisley. When conditions are right, a big fog bank sometimes forms over the lake and creeps up slope across the field, producing at times a spectacular foreground for the rising sun. The clouds were pretty dense and gloomy on this day, though, and the sunrise was humdrum. Somber gray skies prevailed until mid-morning. From Paisley, I continued southwest on 42 through Altoona, arriving at Sunnyhill Restoration Area by about 7:45. There is a small tract of live oak hammock there that is lovely in its own right, drenched with epiphytes like Spanish moss and resurrection fern, but there were no birds active on this chilly gray morning. The pastures near the horse trailer parking lot produced a flock of killdeers calling and wheeling, and a barred owl called from a distant hammock, but mostly it seemed as if the birds were still waiting to begin their day.

Sunnyhill Restoration Area

I backtracked on 42 to SW 182^nd Avenue Road (Avenue Road ? Isn’t that a bit of overkill?) and headed north a few miles to FR14, and then north on FR 05 (labeled SE 205^th Ave and Nfr 579 on Google Earth). I first visited Forest Road 05 a few months back and was struck by the incredible diversity of habitats it traverses.

The predominant habitat along FR 05 is scrub, but that simple statement doesn’t begin to hint at the wide range of structural and floristic variants that scrub encompasses. From where I started at its intersection with FR14 on the south to its terminus where it intersects FR50 (Hopkin’s Prairie Rd) some fifteen miles north, FR 05 traverses pretty much every stage of the scrub successional cycle, from recently burned tracts containing nothing but charred trunks and a few scattered survivors to mature monoculture stands of old sand pine, ready to be burned or harvested. And everything in between. Throw in non-scrub habitats, such as the frequent ponds, wetlands and depressions that support different plant communities and the result is that while cruising FR05, you are rarely in the same habitat type for more than a mile or so. If that.

Words are inevitably inadequate to describe the charm of these scrub habitats. Perhaps images are more revealing.

Mixed scrub

A grassy piney depression that clear on what this habitat would be classified as.

A grassy piney depression amid the scrub. I’m not sure what this habitat would be classified as.

Gorgeous Grassy Prairie

An open savannah-like tract in the midst of the scrub

The desolation of recently burned scrub.

A couple of northern flickers were hanging around and doing the wicka-wicka pair-bonding display in one of the few remaining sand pines.

Regenerating early regeneration scrub, with mature sand pine scrub in the distance

Regenerating early stage oaky scrub, with mature sand pine scrub in the distance

For the first hour and a half on FR05, bird activity was still quite low. Cold, cloudy conditions often stimulate birds of forested habitats to stick close to dense cover; trying to find birds at the edges created by the forest roads can be pretty non-productive. Several big flocks (~100) of American robins flew over, but I only saw a few in the scrub. A couple of flocks of blue jays and an occasional house wren or cardinal pair were about all I could kick up at first. By 10, the cloud cover began to disperse, the sun blazed through, and the birds began to appear. The various forms of scrub can host big numbers of wintering passerines, including half a dozen or more species of warblers. In fairly short order, I was able to tick off pines, palms (a couple of westerns but mostly easterns), yellow-rumps, yellow-throateds, black-and-white, common yellowthroat, a distant ovenbird chewking repeatedly, and several orange-crowned warblers. Eight species of warblers within an hour or two in mid-winter? How are you going to beat that?

Yellow-throated warbler

Palm warbler, eastern race

Pine warbler, male

Pine warbler, 1st year

Black-and-white warbler

Blue-headed vireo

Orange-crowned warbler. I found these birds several times in different mixed species flocks.

As FR05 approaches it’s intersection with State Road 40, the main east-west artery through the forest, one can, if one likes, take a 3/4 mile jog to the southwest to the boat ramp on Half Moon Lake. Expert Florida naturalist and biologist Dr. Steve Christman tells me that he sees bears in this area all the time, but I saw none on this day. Lots of bear scat, though, along with that of other carnivores. In some areas of the forest, it seems there is a pile of scat in the road from bear, bobcat, coyote, raccoon, or some other mid- to large-sized mammal nearly every 50m or less. Which does hint at the answer to the age-old riddle – does a wild bear shit in the woods? Not all the time, apparently.

Cladonia lichens in a fringing hammock around Half Moon Lake

Taking the dead-end spur to Half Moon Lake will spoil the loopular purity of this route, though, so it shouldn’t be indulged in cavalierly.

Across State Road 40, FR05 continues north for another several miles, in the process dipping down to the elevation of and skirting the edge of lovely Zay Prairie. Just one of many grassland/seasonal wetlands that FR05 passes, but certainly the most fully visible from the road.

Zay Prairie

Just before FR05 ends where it intersects FR50, there is a network of trails in the Lake Eaton Sink area. A small parking lot marks the trailhead; it was here that I digitally photographed my first Florida scrub lizard (Sceloporus woodi) several months ago. No scelops out on this chilly day, but I noticed something else there for the first time. Signs with some of my photographs on them! Tres cool.

Red-shouldered hawk, prickly pear and common yellowthroat by the artist once known as Destructo

Red-shouldered hawk, prickly pear and common yellowthroat by the artist formerly known as Destructo

The turn to the east of the ultimate Ocala loop comes at FR50; I turned right there yesterday, but a turn to the left will take the non-loop fixated visitor to some lovely hammocks and wetland habitats surrounding Lake Eaton. And Lake Eaton itself is charming.

Mixed scrub along FR50

Forest Road 50 eventually takes you by one of the most gorgeous areas of the forest I’ve yet seen, Hopkin’s Prairie. And that’s a viable option for modifying the ultimate Ocala loop if you choose to do so. But I didn’t. I turned south on FR33 west of Hopkin’s Prairie, stayed on that well-traveled road for scarcely more than a mile, then turned east on FR46, which skirts the northern edge of magnificent Juniper Prairie Wilderness. If I had to pick one road for birding out of all the roads I’ve been on in the forest, it would probably be this one. It runs only about 5 miles from its intersection with FR33 to where it ends at State Road 19 just south of Silver Glen Springs, but the range of both scrub and sandhill habitats found in this relatively short stretch usually produces a wide diversity of cool birds. Including lots of Florida scrub jays. Last winter during the red-breasted nuthatch invasion, I found these endearing little scuts on several occasions in the mature sand pine scrub tracts along FR46. The vast landscapes of low-stature oaky scrub visible to the south of this road are awe-inspiring.

Red-breasted nuthatch from FR46 in November, 2012.

Wintering eastern towhee. Our breeding towhees have white eyes. Towhees are abundant in the oaky scrub of Juniper Prairie

At State Road 19, the slow-rolling, intense birding part of the loop ends and gives way to the high-speed, vista-scanning form of birding. I usually take 19 back to 40 and then work my way back to Deland from there, still passing through the vast Ocala National Forest along much of the route. But that only works if you live in Deland. For those of you non-DeLandites, feel free to modify the ultimate Ocala loop once it reaches SR19 as necessary to return to your place of origin or nearest convenient parallel dimension.

A snipe hunt in Ocala National Forest

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Title credit: E. Eugene Spears

January 12, 2014

Regenerating sandhills on FR11.

My buddies for life (I think) Skeate and Spears made their annual trek from the hellish cold of Banner Elk, North Carolina to pay me a visit this week. The three of us met as grad students in the fabled zoology department at UF back in the 80s, and they have been my closest friends since. All of us were Florida newbies, and we learned about community ecology and the terrestrial ecosystems of peninsular Florida from the same mentors at around the same time. Nonetheless, it was a major rush for me to spend a couple of days sharing my recently ignited passion for Ocala National Forest and its diversity of plant communities and landscapes with them by visiting a couple of my favorite spots in the forest. We had all taken Community Ecology at UF with field trips led by the great man, Dr. Archie Carr, whose knowledge and understanding of Florida natural history and ecology were nothing short of miraculous. So by comparison, my puny attempts to enlighten them somewhat about the scrub, high pine, and associated habitats were kind of laughable. But all we can do is take what we’re given, G. We had no particular target taxa in mind; we were just road-cruising, happy as scallops for whatever natural history nuggets we might chance upon.

In fact, this post might be better called the anti-snipe hunt, as it is antithetical in nearly every respect to the traditional snipe hunt. In a regular snipe hunt, a naïve nimrod is stationed somewhere in purportedly suitable habitat, preferably on a dark, moonless night, to wait for the mythical snipe to appear and bag it. It’s a very focused pursuit, but typically produces no useful outcome other than amusement for the instigators. By contrast, we were three unfocused but somewhat knowledgeable fellows, looking for nothing in particular, nearly constantly in motion, covering a lot of territory on a bright morning. And our efforts produced several useful outcomes, including crippling views of the legendary snipe. No capture other than digital, though.

Coachwhip

On Friday, we first visited a tract of private property a bit south of Astor Park that included the remains of some old sand-mining operation, and then we headed southwest towards the Alexander Spring section of the forest. As we tooled southeast on FR18 towards the 52 Landing boat ramp on Alexander Springs Creek, we saw (incredibly briefly) a 3-4’ snake speed across the road and into the cover along the margin. Perhaps as quickly as I’ve ever seen a snake cross a 20’ wide roadbed. I didn’t even get a look at the head before it disappeared out of sight, but the sand-colored caudal half of the body and rapid rate of transit was enough to identify it: coachwhip. As we savored the buzz of the sighting, we reminisced about the coachwhip we saw while on a Community Ecology field trip to the Ordway Preserve over 30 years ago. Most of the dozen or so grad students in the class, and a couple of faculty, were in the departmental van ahead of me. As I still am, I was a driving fool and so was following the van in my tortured old ’75 Ford Futura. I had to slam on the brakes and skid to a sudden stop in the sugar sand ruts as the van ahead of me did the same; the side door opened and about a half-dozen people exploded out of it in pursuit of the coachwhip that had crossed the two-track we were driving on through the successional pasture. Most of these herpetophiles were young men in their physical prime, but the great Dr. Carr, then somewhere in the neighborhood of 71 years old, beat them all to the beast and with a great flying leap pinned the coachwhip with his torso.

Coachwhip

The nasty masty turned around, clamped down on Dr. Carr’s nose, and held on. And Dr. Carr stayed chill, knowing that any movement might cause the snake to rake his not-insubstantial rows of sharp teeth through his rostral flesh. After a few seconds, the coachwhip, still mostly immobilized by Dr. Carr’s weight pressing on him, let go of his nose and looked around. One of the other members of the group immediately grabbed the snake a bit too far down the neck and pulled it from underneath Dr. Carr. The coachwhip promptly latched onto his hand and raked, causing him to begin gushing blood from numerous small lacerations. After they released the snake and it began its retreat from the band of stinking primates, I took two photographs of it as it periscoped and scanned its surroundings before boogying at top speed. When I received and viewed the processed slides, I saw that a small turkey oak seedling beside the snake was speckled with blood.

Skeate, Spears and Buckeye at Alexander Spring Creek.

Buckeye. This charming little canine played no significant role in any of the adventures related here, but he’s so damned handsome I had to include his portrait.

We had no comparable adventure with the Ocala coachwhip yesterday; it was gone before the three of us had even processed our sensory input and identified the snake as a coachwhip. Conclusion from this and countless other anecdotal evidence: Dr. Archie Fairly Carr Jr. was a great, great man.

Dr. Archie Carr, Jr. The most amazing man I've ever known personally.

Dr. Archie Carr, Jr. The most amazing man I’ve ever met.

The rest of Friday’s trip, which included Paisley Road and FR06, was lovely but unproductive of anything other than stunningly beautiful habitats. Our sampling of gorgeous and diverse habitats resumed on Saturday, when we took FR11 north from SR40, a bit west of Astor Park, and followed it to its end at Ocklawaha Lake, on the boundary of Ocala National Forest. Unlike most forest roads, the stretch of FR11 between SR40 and its intersection with SR 316 just northwest of Lake Kerr is paved. This section of FR11 passes mostly through scrub, though the range of scrub subtypes spans nearly the entire gamut, from recently harvested clearcuts to mature, even-aged stands of nearly pure sand pine, and all the intermediate successional stages connecting these two endpoints.

The first of the two black bears we saw on FR11.

Once north of 316, as FR 11 approaches the Riverside Island tract, the road reverts to the more typical yellow sand. It was here that within a stretch of no more than a mile or two we spotted two different black bears poking around the road margins. We stopped and glassed both animals for a minute or two from a distance of a couple hundred yards, and they glanced up the road at us but remained unconcerned until I tried to drive closer to them, at which point they both slowly retreated back into the sand pine scrub. It seems like there must be some meaning to the observation that in the 35 years I’ve lived in Florida, I’ve seen black bears in natural habitats (I’m not including the young bear I saw at 2 a.m. in the morning from about 5’ away destroying the bird feeder and pole just outside the window of my DeBary home, nor the one that wandered onto the Stetson campus one fall a few years back, climbed up into a smallish oak tree in front of the student union, and snoozed there for several hours as students and staff treated it like a rock star and gathered around to ooh and aah) maybe 11 times, and that eight of those sightings have been in the last 6 months. But more likely it is just a reflection of the random and unpredictable nature of actually seeing uncommon and wary wildlife.

Regenerating sandhills

Further north on FR11 the habitat transitions from scrub into regenerating sandhills, and then a bit further on, mature tracts of longleaf savannah where I had several killer encounters with roving clans of red-cockaded woodpeckers last year. The bright cloudy skies on this breezy morning provided the perfect diffuse lighting to accentuate the panoply of brown hues produced by the numerous conspicuous grasses. Luscious golden browns of Andropogon, creamy tans of wiregrass, a diverse range of intermediate tones from other grasses and senescent forbs – it’s a beautiful time of year to be in the sandhills.

Mature sandhills with wiregrass

At Rodman Dam, I was hoping for a variety of dabbling and diving ducks, but the only aquatic swimmers to be found were big flocks of American coots. While watching a couple of killdeer exploring the broad grassy berm of the dam, I saw a lone Wilson’s snipe toddling slowly up the slope. Confident that it would flush with a buzzy prrrrrt as soon as I got anywhere close to it, I idled towards it hoping to grab a shot or two. And behaving exactly like a consummately cryptic bird should, it surprised me by never flushing, ultimately allowing me to drive within about 15 feet and fire away to my heart’s content. It was still hunkered in the same spot as I slowly pulled away.

Wilson’s snipe.

The friends I made in graduate school were some of the finest people I’ve ever been privileged to know, and those relationships seem to sweeten and intensify with time like a fine wine. Can’t go back to those halcyon, treasured times, I know, but spending time with old friends like Skeate and Spears is maybe the next best thing.

Coco and her dude.

The post-script to this story concerns stuff we didn’t see. Before their visit, I was totally jazzed by the prospect of showing off the pair of painted buntings that had been visiting my gardens for the previous couple of weeks. But both those birds disappeared about a week before my friends arrived, and despite my repeated entreaties to the bird gods, the male never returned while they were here. Coco, the female, did put in brief appearances on Friday and Saturday afternoon, but the incomparably beautiful male waited until 3 hours or so after they pulled out this morning to make his return. The serendipity of natural history. Next year, my friends.

Reconnoitering the rim

September 14, 2013

Taking photographs is one of my main reasons for going into the field. The most important reason is, of course, to see fascinating flora and fauna, and perhaps learn a bit about how they make their way through the world. But capturing images of at least some of the plants and animals runs a close second. Those images are almost entirely for my own purposes; only a very small fraction are ever seen by anyone other than me. So maybe it’s not a big deal that the most stunning image I’ve experienced in some time is one that I will never be able to share. Driving north on SR19 through Ocala National Forest on Saturday morning, about 15 minutes before sunrise and a mile or so north of Silver Glen Springs, I saw an animal crossing the road a couple hundred yards ahead of me. No other traffic in sight. The telltale trot told me immediately it was a coyote. I don’t see coyotes often, and truth be told, I don’t get that excited about mammals in general. Stinky nocturnals, for the most part. But I adore dogs of every size, shape and temperament. Seeing a wild dog is for me a pinnacle experience.

It was during that transitional period between dawn and the full light of sunrise, when colors are beginning to become apparent, but still somewhat muted. I was on the coyote in no time, and she maintained her steady lope across the road and onto the shoulder, about a fifteen foot wide swath of mowed grass, ending where the dense ground cover and low vegetation of oaky scrub began. As I passed her, now slowed down to maybe 30-40 mph, she stopped at the edge of the shoulder, turned broadside to me, and watched me as I drove past. I locked eyes with her. Then she turned and was gone. I don’t know exactly what happened to my neurochemistry at that moment, but I’m pretty sure it involved a massive flood of several happy neurotransmitters. Dopamine, adrenaline, oxytocin – who knows? As I drove away from that brief but intense moment, I felt changed, and elated in a way I don’t often experience. Privileged. That image, that moment of looking into the eyes of “God’s dog”, will be forever burned in my brain. I couldn’t help but wonder later what was going on in the coyote’s agile mind. For me, it was a feeling of intense awe and admiration. For her, I can only guess. Curiosity, for sure, probably a bit of fear, and if coyotes have anything like a collective unconscious or shared genetic memory, perhaps a big dose of disgust and mistrust over the way humans have for centuries abused and tortured these beautiful little canids. Hard to imagine a better start to the morning, even if I have no photograph to document the moment.

Ocklawaha Lake from the Kirkpatrick Dam

Ocklawaha Lake, aka Rodman Reservoir, was my first destination, and from there I planned to explore some new roads along the northeast rim of the forest. Several weeks ago I discovered serendipitously that one of my favorite roads through the forest, FR11, continues over the Kirkpatrick dam that forms Ocklawaha Lake. The dam was built as part of the abandoned effort to build the Cross-Florida Barge Canal across the peninsula in the ‘60s, and it remains controversial, pitting environmentalists who would like to see the dam removed to restore the Ocklawaha River to a free-flowing state against sportsmen who wish to protect the outdoor recreation opportunities it provides. I just wanted to see migrant birds. I was hoping that some of the floodplain forest in the area would be teeming with brightly-colored warblers and other neotropicals. A couple dozen or so herons and egrets (great blues, little blues, snowies, great egrets and a single green) and dozens of vultures, who seemed to regularly roost on the dam and along the road that crosses it, were the only birds I could turn up there.

Snowy egret and great blue heron. Ocklawaha Lake

Dubbed “Sand Land” by some creative soul on Panoramio, this scrub barren on FR 11 just south of Ocklawaha Lake is the result of off-road vehicle abuse of the scrub habitat. Even though vehicular use of this tract is no longer permitted, it remains in this degraded state.

Forest Road 74 crosses Forest Road 11 just south of Ocklawaha Lake. I drove west on FR74 into unexplored territory. A mobbing response by a small flock of passerines included several towhees in various states of moult and dishevelment, a couple of prairie warblers, and some residents like Carolina wrens and cardinals. A bit further down the road, a second mobbing flock was more diverse, and contained several northern parulas, a yellow-throated warbler or two, scrub and blue jays, and a distant Empidonax flycatcher I didn’t come close to photographing. I was pretty pleased with myself just to be able to ID it as an Empidonax; identifying it to species, without vocalization, is outside of my skill set.

Male eastern towhee, still looking sub-prime from his post-nuptial molt.

Female northern parula

Leaving that flock, I spotted a medium-sized snake stretched out in the bare sand of the scrub alongside the road. Black racer. Surprisingly, he let me drive to within 10’ or so without bolting. As I moved slowly to get the camera into position, I was holding my breath that I wouldn’t spook the racer before I got off at least a few shots in this delicate, diffuse morning light. Black racers are pretty easy to find, but not easy to photograph for me. These are intensely visual snakes, and I suspect in my entire experience with the species, I’ve only seen them a few times before they have seen me. A much more common experience is to spot one while glassing the habitat for whatever, only to realize the snake already has a visual lock on me. From distances up to 30-40’ away. These snakes don’t miss much. On the occasions when I’m fortunate enough to watch one hunting my backyard and gardens, I’m always struck by their awareness of their environment, periscoping frequently to elevate their head above the ground cover and assess their surroundings. Typically, any quick movement on my part precipitates a rapid retreat to cover by the snake. Which is exactly what this racer did the first time I tried to inch a bit closer for a better shot.

Black racer basking

Black racer

Black racer periscoping. From my yard, hence the noxious St. Augustine grass

FR 74 leaves the forest a couple of miles west of FR 11 and passes through private land; I took FR09 south to get back into the sparsely traveled roads of the national forest. Another fine mobbing flock in an ecotone between oaky scrub and sand pine scrub was the best of the morning – perhaps 15-20 birds, including scrub jays, towhees, prairie warblers and northern parulas, a white-eyed vireo, tufted titmice, cardinals, a woodpecker or two, Carolina wrens. The usual suspects. And ovenbirds. Once again this weekend, they were chewking from dense cover in nearly every mobbing flock I encountered.

Florida scrub jays

Prairie warbler

Immature female eastern towhee molting into her first adult (basic) plumage

Ovenbird

FR 09 in this area is notable for another reason – topography. Not much by most standards, but enough to allow extended views of the surrounding habitat mosaic. The presence of actual hills and draws in the forest is always a welcome surprise.

Topography (of sorts) on Forest Road 09

From FR 09, I took FR70 back to the east. Soon after passing into one of the large tracts of clearcut sand pine scrub, I saw a large, dark raptor flying low across the landscape and swoop up into the top of a lone sand pine that had been left standing. Profile and flight pattern didn’t look like the raptors I see most often, but as soon as it perched I could see the ear tufts. A great horned owl, hunting (?) in broad daylight, on a sunny morning, around 10:00 a.m. That’s something I don’t see often. Until earlier this year, I’ve always thought of great horned owls as a “bird of the day” species. Typically I see them only a few times a year. Since June, I’ve seen great horned owls at least 10 times in a half-dozen or more different locations. The serendipity of birding.

Great horned owl, hunting at mid-morning.

Great horned owl youngster, from earlier this year at Lake George Conservation Area

Some time around 1100, I made it back to familiar ground; FR 70 intersects FR11 just north of the Riverside Island tract where I have had such good luck finding red-cockaded woodpeckers this year. None today – it was far too late in the morning and too warm for much bird activity, though I did find a pair of American kestrels hunting in the same open sandhills tract where I have seen them before. Almost certainly a breeding pair; I haven’t seen any migrant kestrels yet this year at the spots where I usually find them.

Forest Road 70 where it passes through an isolated live oak hammock amidst the sandhills

While driving south on FR11 through majestic mature sandhills, I was watching some mixed roadside clumps of goldenrod and evening primrose for pollinator activity and noticed the reticulate wings of some rather large insect in the foliage of one of the primroses. It was one of the larger species of antlions (Myrmeleon sp?) that had been snagged by a nearly invisible green lynx spider (Peucetia viridens) only moments before. It was still oozing hemolymph from the spider’s puncture wounds, and it seemed to still have a glimmer of life in its many eyes. Green lynx spiders – what fierce predators those lovely arachnids are. There don’t seem to be any size limits or taxonomic boundaries on the prey these oxyopid spiders will tackle. Tough luck for the antlions and myriad other prey taxa.

Green lynx spider (Peucetia viridens) with antlion prey

From a coyote to a lynx – a good morning for the predators, and me. If I continue exploring new forest roads at my current pace, I should have thoroughly traversed the forest by the time I’m ready to retire. Ocala National Forest – the gift that keeps on giving.

Volusia Naturalist

A celebration of natural history

Category Archives: Ocala National Forest

Thrush passages

December 30, 2016

Learning snakes

August 20, 2016

References

May, P.G., Farrell, T.M., Heulett, S.T., Pilgrim, M.A., Bishop, L.A., Spence, D.J., Rabatsky, A.M., Campbell, M.G., Aycrigg, A.D. and Richardson, W.E., (1996). Seasonal abundance and activity of a rattlesnake (Sistrurus miliarius barbouri) in central Florida. Copeia, pp.389-401.

Roth, E., May, P., & Farrell, T. (1999). Pigmy Rattlesnakes Use Frog-Derived Chemical Cues to Select Foraging Sites. Copeia, 1999(3), 772-774.

Phillips, B. L., & Shine, R. (2006). An invasive species induces rapid adaptive change in a native predator: cane toads and black snakes in Australia.Proceedings of the Royal Society of London B: Biological Sciences,273(1593), 1545-1550.

Cold-blooded mothers

December 13, 2014

Postscript, December 21:

References:

Caniphilia

October 18, 2014

References:

Shameful shit

May 18, 2014

Why no sparrows?

May 10, 2014

Reference: Cook, R.E. 1969. Variation in Species Density of North American Birds. Systematic Biology 18 (1): 63-84.

Lekking in DeLeon Springs

March 8, 2014

The Ultimate Ocala Loop

January 26, 2014

A snipe hunt in Ocala National Forest

Title credit: E. Eugene Spears

Reconnoitering the rim

September 14, 2013

December 30, 2016

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August 20, 2016

References

May, P.G., Farrell, T.M., Heulett, S.T., Pilgrim, M.A., Bishop, L.A., Spence, D.J., Rabatsky, A.M., Campbell, M.G., Aycrigg, A.D. and Richardson, W.E., (1996). Seasonal abundance and activity of a rattlesnake (Sistrurus miliarius barbouri) in central Florida. Copeia, pp.389-401.

Roth, E., May, P., & Farrell, T. (1999). Pigmy Rattlesnakes Use Frog-Derived Chemical Cues to Select Foraging Sites. Copeia, 1999(3), 772-774.

Phillips, B. L., & Shine, R. (2006). An invasive species induces rapid adaptive change in a native predator: cane toads and black snakes in Australia.Proceedings of the Royal Society of London B: Biological Sciences,273(1593), 1545-1550.

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December 13, 2014

Postscript, December 21:

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October 18, 2014

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May 18, 2014

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May 10, 2014

Reference: Cook, R.E. 1969. Variation in Species Density of North American Birds. Systematic Biology 18 (1): 63-84.

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March 8, 2014

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January 26, 2014

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Title credit: E. Eugene Spears

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September 14, 2013

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