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.

Of crows, cats and the preservation of sanity

26 Replies

November 11, 2016

All images are linked to larger, high-resolution versions (except for the featured image above). Click to see the larger version.

Wednesday, November 9 didn’t start well. It’s fair to say that it began as one of the worst mornings I’ve experienced in recent memory. I made the 40-minute drive to Seville as the world was just coming awake again, profoundly shocked that the unthinkable had come true. A deep emptiness and sense of hopelessness filled my chest. I felt something like I have in the past when a cherished pet died or a valued relationship ended. Hollow. Struggle as I might, I could find no silver lining in this dark, oppressive cloud that had appeared so unexpectedly. I had been thoroughly swept up into the echo chamber of the mainstream media, and I was totally unprepared for this bleak reality.

So this is a story of escape from the wearying world of humans and their foul doings, and the redemptive, restorative power of nature. The miraculous power of the natural world to rescue one’s mental health and provide a respite from the pervasive reality of the darker spirits of the world of people was no revelation; the natural world has been my therapist and anesthetic from reality for as long as I can remember.

The glorious sunrise in the flatwoods cheered me up for a few minutes, but the release from psychic pain was ephemeral.

Needless to say, relief from the pervasive sense of unreality didn’t come quickly or easily. Even the gorgeous kaleidoscopic sunrise as seen from the open mesic flatwoods of Brooks Road in Lake George Conservation Area buoyed my spirits only briefly. Nature was to have its work cut out for it on this day.

No small amount of credit for preserving whatever modicum of sanity or normality I still have has to go to the American crow and the relationship I’ve developed with these remarkable birds over the last half-decade. My pre-dawn ramblings around central Florida remind me regularly what resourceful, amazing birds these are. I would estimate that on about half of my field trips that begin with a crepuscular departure, the first birds I see as the world just barely becomes visible are American crows. Most often they are performing roadkill patrol, harvesting the bounty of the previous night’s carnage. It seems to be a regular part of the crow’s behavioral repertoire.

Roadside crows scavenging the previous night’s roadkill are often the first birds I see active in the pre-sunrise hours while most birds are still snoozing. Industrious birds.

At home, my daily visits with the clan of American crows that has been gracing my yard with their daily presence over the last five or six years have given me immense and indescribable pleasure. As John Marzluff and other crow researchers have shown convincingly, American crows recognize individual humans and remember the “good guys” and “bad guys” for a long, long time. My local crows have decided I’m a good guy. As I write this on my back porch, one of my friends just flew into the yard, landed about 25’ away from me, eyed me for a second, and the boldly strode forward another 15’ feet to load up on the pellets of dog food I had scattered earlier in the morning. Being 10′ away from a trusting wild crow, who can be among the wariest of birds, is a transformative experience. I bid him good morning (actually I told him “hello crow”, which is how I address all of them on first appearance), and chatted with him inanely as he scarfed dog food, then flew off to cache most of it. Yes, I talk to my crows regularly, and I’m quite convinced they understand some of what I’m saying. Crows that have gathered around the yard, hanging on the periphery, will immediately fly closer when I say the word “food”, which I do each time I toss dog food pellets into the feeder area as they watch me.

I love these birds like family.

But what do they really think of me? Who cares? They come see me, and that’s enough.

One of the banner days of each summer is the day the crow family brings their newly fledged offspring to the yard to begin teaching them the complex business of how to be a crow – in this case, who they can trust, and who they can’t. Building a bond with each year’s new generation of crows is an experience I’ve come to cherish. I could drivel on for pages about my experiences with my home crows and what they have taught me, but that’s not really the point here.

Okay, young dude, let me show you what’s what. A yearling crow is tutoring his fledgling sibling. Crows exhibit cooperative breeding.

Fledgling crow taking stock of this strange hominid

What is more pertinent is the delusional fantasy I entertain sometimes that American crows are part of a vast and complexly connected information network that is capable of disseminating knowledge quickly and efficiently throughout crow world. That is to say, I sometimes entertain the demented notion that American crows everywhere know who I am, know that I’m one of the good guys, and treat me accordingly. But I digress. Back to Tuesday morning and my fragile state of mental health.

I was traveling to Lake George Conservation Area to continue my sabbatical research project investigating mobbing behavior. Up until this catastrophic Wednesday morning, the fall semester had been hands-down the most rewarding and enjoyable term I’ve spent in my nearly 30 years of teaching at Stetson. This is the fourth sabbatical semester I have been awarded, and the first devoted entirely to field research. Being in the field at a variety of different sites nearly every morning at sunrise has been a revelatory experience to me. The intense exhilaration of anticipating each day’s jackpot of natural history observations has been a phenomenal motivator to get my lazy ass out of bed at 0 dark 30, something abhorrent to my basic slothful nature. But in truth, on this Wednesday morning I had strongly considered staying in bed all day and just hiding from this hateful world. I didn’t, and for that I’m thankful.

Watching the sun come up in a different habitat every morning this semester has been a wondrous experience.

Truck Trail 1 in Lake George Conservation Area makes up but a small leg of the 11-mile driving route that wends through the panoply of habitats comprising this priceless chunk of property. Which should be sold to private landowners, in the political view of some, I suppose. The idea of divestiture of all public lands and sale to the highest bidder shocks and repels me to my core.

At its intersection with Aces Road, one wet corner holds a thriving population of pine lilies, Lilium catesbaei, that puts on a spectacular display of big gorgeous blooms every September. I turned right at this intersection to follow Truck Trail 1 the half-mile or so to its terminus, a gated fence that marks the boundary between the conservation area and adjacent private land. It was on this section of TT1 a few months earlier where I watched a male bobwhite just sitting calmly in the road, brooding his batch of a dozen or so recently hatched chicks under his wings. Which I didn’t realize until he eventually stood up and all the little quailets scurried for the nearest cover. Indescribably precious.

The pine lily patch at Aces Road and Truck Trail 1

Pine lily with green lynx spiders, male below and female in the corolla

Papa quail brooding the kids

Towards the end of Truck Trail 1, the mostly mesic flatwoods of the conservation area open up into a strand of depression wetland dominated by bald cypress, and chockablock with lovely fall flora on this gray, foreboding morning. In particular, a glowing cluster of Bidens mitis seemed like a nice foreground element for a habitat shot of this wetland, so I pulled to the side of the berm to play around with the scene a bit. Coincidentally, though I pass this spot each week during my transit of the conservation area, in the morning it is strongly backlit, and on sunny days, the light is simply too harsh and overpowering for habitat shots in that direction. The thick overcast turned the sky into a giant softbox on this morning, without a hint of backlighting or any directional light at all. That’s the sole reason I had stopped at that particular location this morning. Pure serendipity.

This is the landscape I was photographing. If I hadn’t been stopped here quietly for several minutes, it’s very unlikely the bobcat would have wandered out into the road as she did

After sitting there for several minutes, trying different exposures and compositions, a movement on the road ahead of me caught my eye, and I looked up to see the south end of a female bobcat heading north. She had emerged from the woods, apparently completely unaware of my presence in a blue Honda, perhaps 75 meters away. So I moved slowly, grabbed binos, and watched this beautiful felid through my windshield as she blithely sauntered up the road, looking left and right, but never behind her. It was an excruciatingly difficult decision to simply watch her while I could, and not try to surreptitiously start the engine and creep forward to an orientation where I could photograph her out the driver’s side window. I knew she would be gone in a flash at any unexpected sound or movement. So I watched for one or two minutes as she slowly made her way 30 meters or so up the road, around a bend, and out of sight. I waited about 30 seconds and started the car and repositioned myself, set up my camera on the beanbag, and got ready for the photo op that I was very skeptical would happen. (And almost didn’t, as my camera began to freeze up in a way that it has been doing sporadically and unpredictably for the last several weeks. But that’s another story.)

John Serrao doing one of the many things he does so well

At this point, I have to once again thank my friend John Serrao for telling me stories a couple of years ago about attracting predators using recorded or imitated rodent distress calls. John had told a remarkable story of having a weasel walk across his foot while he was making squeaky noises with pursed lips (as I recall; mea culpa if I’ve mangled the details, John). Soon after that conversation, I went online and downloaded a half-dozen .mp3 files of various rodent/rabbit distress calls. Perhaps a year later, those recorded calls paid off bigly when I was able to call in and photograph a pair of gray foxes in Ocala National Forest. See Caniphilia for an account of that experience. The rodent distress calls attracted a mildly interested coyote at Lake Apopka Wildlife Drive earlier this year.

Intrigued gray fox in Ocala National Forest.

This coyote came up this road several hundred meters to check out the dying rodents

So, thanks, John. The calls worked again, but with an unexpected twist. Within a minute or so of playback of rodent squeals through my car stereo, my friends joined the cast. From maybe 150 meters away, I saw and heard a pair of American crows coming towards me. But not directly, as if they were responding to the playback – this pair was moving towards me obliquely, flying between perches in small increments of 10-15 meters. As they continued moving in my direction, I estimated that their trajectory would bring them to the edge of the road maybe 40-50 meters in front of me. Prior to their appearance, I had focused my attention on the bend in the road 100 meters away where I had last seen the bobcat round the corner. I expected her, if she responded, to come back around the corner where I last saw her. As the orange buffoon might say, “WRONG!!”.

My first view of the bobcat, heralded by a pair of sentinel crows above

She popped out of the thick grass and low vegetation right where the crow’s path intersected the road. They were tracking her. And keeping me informed of her progress, in my warped view of reality.

For the next minute or so, my sense of time and all extraneous sensory experience ceased. Every scintilla of my limited mental capacity was focused on photographing this beautiful girl. She stepped out onto the margin of the berm road and eyed me for a few seconds. At one point, she opened her mouth, and perhaps vocalized towards me. As my shutter was oscillating continuously in high-speed burst mode, I heard nothing, and didn’t even see the open-mouth display until I processed the photos. She turned back towards the cover on the road margin, and I thought for a moment that this exhilarating encounter was over. WRONG!!

Where the hell is that dying rodent? Did that blue Honda just run it over?

I didn’t even notice her doing this gape while I was photographing her. If she vocalized, it was drowned out by the continuous chatter of the shutter in high-speed burst mode

She turned back around, walked to the middle of the road, stopped in a curious semi-squatting pose (she didn’t urinate), and gave me a long, piercing look, all the while rotating and twitching her tail like a neonate pigmy rattlesnake engaged in caudal luring. I was in awe. After about 15 seconds of this display, she casually continued her walk across the berm and into the woods. And that was the last I saw of her.

Twitching the tail

But not the end of the experience. For the next five minutes or so, I watched and listened as the crows continued to track her, from 30-40’ up in the pines, calling in clusters of two-three staccato caw notes. I was able to keep track of her movement for several hundred meters as she moved away from me through the flatwoods. With my buddies keeping me informed every step of the way.

Departure

And like that, it was over. No more than 2-3 minutes of direct observation of this amazing animal, but it left an indelible memory that will nurture me for perpetuity. And temporarily dispelled the depression and despair that dominated my mood on that bleak morning.

So to John, the crows, and especially the magnificent bobcat, I say thank you for taking my mind off this horror show we call reality, if only for a few minutes. Thank you for whatever shreds of sanity I’m able to cling to during these madhouse times.

What was that snake thinking?

6 Replies

September 6, 2016

I’m intrigued and mostly mystified by the cognitive processes going on in the minds of “lower” animals like snakes. Observing snakes in captivity and in the wild has at times left me with the impression that snakes aren’t the greatest thinkers on the planet; one mutt rat snake that I had for years tried on several occasions to swallow itself, beginning with its tail. It was so determined to self-ingest that I kept a wash bottle of ethanol nearby for those suicide attempts; a little squirt in the corner of his mouth was apparently distasteful enough that he would rapidly egest that part of his nether half already swallowed. Which could be as much as a quarter or more of his body length. That couldn’t have ended well. But somehow he survived the multiple auto-cannibalistic episodes.

Arboreal rat snakes, like these black rat snakes (Pantherophis allegheniensis) spend much of their days watching the comings and goings of their fellow creatures. Then go out and eat them.

On the other hand, watching the intent, patient gaze of some of my big yellow rat snakes, who would bask immobile and watch me for hours made me wonder about the amount of information these big arboreal snakes might be soaking up. Research on gray rat snakes (Pantherophis spiloides) in the southeast reveals a sophisticated learning lifestyle; they spend hours to days watching their surroundings from an aerial lair, in the process detecting and remembering the presence of rodent runs, birds’ nests, and other potential prey (Mullin and Cooper, 1998). When they are hungry, they dash out of the pad to pick up some groceries. That’s pretty amazing behavior for a snake.

What is this black racer (Coluber constrictor) thinking about? If I had to guess, I’d speculate that these guys are among the more intelligent of snakes

How do they know how to do this? It’s hard to know what’s going on in the minds (do non-human animals have minds, or just brains?) of animals from the perspective of a mechanistic understanding of cognitive processes. Neurobiologists and animal behaviorists just don’t know that much about some very basic aspects of mental functions. How and how much do animals learn? Do animals think? Can they reason and perform other logical operations? Do they have emotions and self-awareness? Do individual animals have distinct “personalities”? Do they interact with other members of their species based on what they think is going in in the other animals’ thought processes, the so-called theory of mind? These are very difficult processes to study in animals, who selfishly refuse to describe to us what is going on in their heads. Conclusions about mental processes must be inferred indirectly from specific behaviors exhibited under controlled lab conditions.

Our lack of a deep understanding of the mental capabilities of our fellow animals has one upside – it allows me to speculate foolishly and egregiously about the thought processes of snakes, which I will do below. The thought processes in question stem from my observations of one of the most audacious and single-minded behaviors I’ve ever seen by a wild snake.

Around 10 yesterday morning, I had nearly completed the 11-mile Lake Apopka Wildlife Drive. I was traveling west on Interceptor, just south of the sod fields that had been producing buff-breasted sandpipers and some other notable birds in the last few days. I had the road to myself, so I decided to do a 180 and park my car facing east on the north shoulder of the road so I could scan the flooded fields in their entirety from the driver’s side. As I turned to the right to begin the 3-point turnaround, I saw a small dark snake with rapidly twitching tail near the road’s edge on my left.

The tail twitches that alerted me to the presence of this snake were part of a larger whole-body effort to drag this frog off the road.

A snake in the road with twitching tail usually means a snake that has been recently run over, a snake in the last throes of death. I was prepared to be bummed. The unnecessary death of any snake saddens me, more so than any other kind of animal, for reasons I don’t fully understand. No bummer for me on this day, though. The little serpent, a young eastern garter snake (Thamnophis sirtalis), was very much alive, and intent on completing a bold and ambitious task.

A closer look at the little garter in the blonde shell-rock road revealed the pale underbelly and protruding viscera of some medium-sized frog that had been run over and flattened some time before. The little snake was a bit thin, and well under 10”. The anuran was at least 3-4 times the body weight of the snake, but that disparity didn’t seem to deter him at all. As I watched, and photographed, for the next several minutes, the little garter repeatedly tried to dislodge the frog from the road surface and drag it back to the cover of the road margin. He made no progress at all. The next plan was to try to ingest the frog in situ, beginning with a foreleg. No self-respecting, experienced garter snake would try to swallow an ungainly, long-limbed prey item like a frog by beginning anywhere other than the nose, but this little garter’s mother never taught him that trick.

The right front leg was the preferred point of attack for the little garter. Most of his efforts to swallow the frog started here.

He got pretty far up the leg. The shoulder was a fantasy.

Well that’s not working. Let’s think about this.

Didn’t I hear something once about starting at the head?

On a couple of occasions, the little guy backed off, looked around, took a deep breath, and thought things over. And then returned to the task with renewed vigor. Ultimately he admitted defeat and slithered back into cover without his big dead frog.

What was that snake thinking during this encounter, if anything? Venturing onto the uniformly light-colored road surface was a ballsy move for a small snake that could be eaten by any of several dozen potential predators. And fast, Jack. Any of the common egrets and herons would have been on that snake like ugly on an ape; even a big passerine like a jay or thrasher would have had no problem at all dispatching that little guy.

Any of the herons or egrets would gladly scarf a little garter snake. This great blue has snagged a striped crayfish snake (Regina alleni) much larger than my little garter.

Risk-prone snakes reap the big rewards some times, but they can also pay a heavy cost. Several years ago while returning from Emeralda Marsh on County Road 42 through Lake County, I found a multiple herp fatality on the roadside. A road-killed southern toad lay alongside a DOR cottonmouth. I’m quite sure the toad died first; the cottonmouth was scavenging when it too was hit by a car. No guts, no glory.

Looked like an easy meal, but it didn’t work out that way for this cottonmouth trying to scavenge a road-killed toad.

One possibility is that the snake was behaving entirely according to a reflexive behavioral sequence genetically encoded and neurologically hard-wired. The sensory cues emanating from that dead anuran were probably intense; garter snakes and other members of the genus Thamnophis are heavily reliant on olfactory cues during prey search. For all I could tell, that dead frog was billowing huge ropy plumes of frog essence, a scent so overwhelming that the poor little snake was pulled in unwittingly and unthinkingly as if by a tractor beam.

I am powerless to stop this behavior, the little garter didn’t think to itself.

On the other hand, what if snakes have an active mental life, and some form of information processing that might approach conscious thought processes? Was that exposed little snake frightened? Was he figuratively strutting like Richard Pryor and Gene Wilder in Stir Crazy (https://www.youtube.com/watch?v=kNbZcT8RXgE), thinking “That’s right, I’m bad”? (Remember what I said earlier about foolish and egregious speculation?) I have to think the behavior of that particular snake was in some respects remarkable – not every young garter snake of comparable size would attempt to consume such a massive prey item. In the parlance of behavioral biology, that snake was particularly risk-prone, placing himself at increased risk of predation to get the big payoff. There are certainly other garter snakes out there that would exhibit a more risk-averse approach, and never leave the cover of the roadside. Where do these differences in behavior among individuals come from? Do they reflect genetic differences in programmed behavior, or are they the result of prior experience (learning)?

I’m going to figure this out eventually. If only that butt-ugly stinking primate in the blue car would piss off and leave me alone.

So that’s the meaningless navel-gazing section of this post. The other really fascinating thing about this observation was the behavior itself – consumption of carrion by an animal that is usually thought of as a pure predator. As it turns out, consumption of carrion by snakes isn’t all that uncommon. In a 2002 Herpetologica paper, Devault and Krochmal review the literature on scavenging by snakes, and suggest it is more widespread than previously thought, and in fact may be an integral part of the foraging strategy of some species of snakes. Scavenging is particularly frequent in snakes that rely heavily on odor to find prey (like the thamnophines) and in pit-vipers. Most pit vipers normally consume dead prey – they wait for the animal they have envenomated to die before attempting to ingest it. Often an active prey item may travel a considerable distance before expiring, with the snake eventually tracking (by odor) the envenomated prey item. Consuming carrion that they happen to encounter while tracking prey makes a lot of sense for such a predator.

In this scan from an old transparency, a pigmy rattlesnake approaches (and eventually consumed) a green tree frog that has long ago died from envenomation. It’s entirely possible that this frog was killed by a different snake than this one.

The authors found evidence for scavenging in 35 species of snakes in 5 families, dominated by the pit-vipers and fish-eating snakes, which often are heavily dependent on olfactory cues. Their review turned up scavenging by two species of Thamnophis (T. proximus, the western ribbon snake, and T. sirtalis, the eastern garter snake). Curiously, both records of scavenging by garter snakes were observations of snakes feeding on birds.

It always comes back around to birds, doesn’t it?

References

DeVault, T. L., & Krochmal, A. R. (2002). Scavenging by snakes: an examination of the literature. Herpetologica, 58(4), 429-436.

Mullin, S. J., & Cooper, R. J. (1998). The foraging ecology of the gray rat snake (Elaphe obsoleta spiloides)-visual stimuli facilitate location of arboreal prey. The American midland naturalist, 140(2), 397-401.

Learning snakes

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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.

Daddy duties

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Great crested flycatchers are monogamous, and strongly bonded. I nearly always see them traveling in pairs. That doesn’t mean this male is going to share his cicada with the mate, though.

June 1, 2016

Birds are good parents. Few other comparable taxa of animals, vertebrate or invertebrate, routinely provide a similar level of parental investment and care. Mammals rival them; nearly all mammals retain developing embryos until birth, and provide lots of nurture and resources to the young once born (or hatched in the case of the monotremes). Lactation is a physiologically demanding adaptation, but the costs are borne solely by mothers, except for a couple of bizarre cases in which male mammals lactate. In mammals as a group, less than 5% of species show any male parental care. To be sure, there is huge variation in the degree of male parental involvement in birds, ranging from none in promiscuous, lekking species like sage grouse and manakins, to complete male care in polyandrous birds like phalaropes, where female involvement in reproduction ends with the laying of eggs. Still, on the whole, male birds are far more involved in providing parental care than in mammals.

Great crested flycatcher from Manassas National Battlefield Park. This species is monomorphic; the only way to differentiate males and females is by behavior.

I got a fascinating glimpse into the allocation of parental duties in great crested flycatchers while birding in northern Virginia last week. These observations raise a number of questions about the significance of the male’s apparent participation in nest-building – is he really helping the female, which would constitute true parental investment, or is he simply acting in self-interest to protect his own fitness by preventing access by other males to his mate? I’ll return to those questions in a moment.

Quite likely I wouldn’t have seen these neat behaviors in Florida, though they certainly occur here as well. There is a huge difference between my birding tactics in Florida and Virginia.

Typical birding/photography setup for me – camera on the beanbag, waiting.

I’m not a particularly patient birder or photographer. I do much of my birding and photography from the car, for reasons that are obvious to anyone who knows me. Run and gun is my preferred style. If something isn’t happening at a particular site within 5 minutes or so, I tend to move on. In the places I bird around DeLand, like Tiger Bay State Forest or Ocala National Forest, there is lots of habitat, good drivable roads, and few people. There is no cost to changing locations.

Northern Virginia is a different beast entirely. I return to Manassas, where I mostly grew up, once a year, usually soon after the spring semester has ended, to see my Dad and experience one of the most awesome wildlife spectacles on the planet – the explosion of breeding birds in temperate habitats. At this time of year, evidence of breeding birds is everywhere, in nearly every available habitat. It’s hard to find a location where you can’t hear males of at least a half-dozen species singing, particularly early in the morning. In many habitats, the diversity is far higher. Males are proclaiming and defending territory, and females are finding nest sites and building nests, sometimes with the assistance of their male partners, sometimes without. At this time of year, everything birds are doing is related somehow to reproduction.

Northern Virginia in the spring – breeding birds are everywhere.

Access to good birding habitats in northern Virginia is a bit more problematic. The entire northern Virginia/Washington D.C./southern Maryland area is one gigantic megalopolis, and remaining natural habitats are becoming more and more fragmented and isolated as development proceeds unabated. For me, birding in northern Virginia requires an additional element of planning – travel between one site and another. It can be horrendous. Birding trips involving multiple locations require careful thought about when and how to move from one site to another to minimize the soul-numbing experience that is northern Virginia traffic.

Manassas National Battlefield Park is 5000+ acres of birding heaven, surrounded by the metastasizing growth of new development hell. Two major commuter arteries, Routes 234 and 29-211, bisect the park. The intersection of 234 and 29-211 is at the center of the park, and marks the location of Stone House, one of the most iconic landmarks of the park. On weekday mornings, between about 6 and 10 a.m., this intersection becomes a huge parking lot, as backups a mile or more long build up. Driving between one site and another within the park can become a nightmare. So my tactics shift. In the parlance of foraging ecology, I switch from a widely-ranging forager to a sit-and-wait predator. My birding consists mostly of staying at one spot for much longer periods of time to avoid driving. This approach probably leads me to see things I wouldn’t have seen using the run-and-gun approach.

The parking area at Battery Heights. The female great crested flycatcher was collecting nesting material from the area around the gate.

Battery Heights is one of my favorite spots in the park. This was an important Union artillery placement during the Battle of Second Manassas. Today, a small, peripheral parking lot allows access to a grove of black walnuts, a couple of 12-pound Napoleon artillery pieces, and some signage, all surrounded by beautiful meadows and woodlands. Infrequently visited by all but the most die-hard of battlefield enthusiasts, I can sit here for a half-hour or more (an eternity for me to stay in one spot) and just wait for cool shit to happen. The walnut grove has turned up orchard and Baltimore orioles in the past; eastern bluebirds nest in the bores of the cannons, and chipping sparrows are nearly always singing nearby. Robins nest in the area. Eastern meadowlarks nest in the pasture. The nearby woodlands are home to typical forest species – I occasionally hear scarlet tanagers and wood thrushes singing from those nearby woodlands. In short, it’s a happening place for birds in spring. Curiously, if I’m to visit this spot in the morning, I have to skirt the periphery of the park and approach it on 29-211 from the west. Battery Heights is about 2 miles west of the aforementioned intersection of 234 and 29-211, which is one of the focal points of traffic hell during the morning drive. If I were to drive directly through the park to reach Battery Heights from the east, I’d have to contend with a drive time of an hour or more. To travel a couple of miles.

She was a bit suspicious of me, but she got over it. I talked it out with her.

So there I was at Battery Heights on Saturday morning, chilling and grooving on the birds. An orchard oriole was singing nearby. I was concentrating on that bird, hoping for a photo op, when I noticed a great crested flycatcher swoop into the corner of the parking lot. She perched briefly on a fence gate, and then dropped to the ground. The area around the gate had been mowed recently, and there was an abundance of fine grass debris from the mowing. She was collecting nesting material. She snatched several bundles of fine grass until her beak was stuffed, then flew away. Nothing that unusual or noteworthy there, though I don’t often see great crested flycatchers come down to the ground. A few moments after the female flew in, though, I saw another flycatcher fly in behind her and land in the walnut tree above the spot where she was gathering nest material. When she flew away, he followed.

This female digs her grass. Me too.

Off she goes.

She flew a couple hundred meters across the meadow towards the deciduous forest to the west, where the pair was nesting. That seems like a long way to travel to gather some plant materials, but apparently her specific needs for nest-lining material were quite stringent. Think about that for a moment – amidst all the different types of plant fibers and materials that are present in an eastern deciduous forest, she still made the decision to travel hundreds of meters across an open pasture, where she is certainly more vulnerable to predation by raptors like Cooper’s hawks. That’s a bird with a very specific need to fulfill.

The pair flew several hundred meters across this meadow just to collect grass clippings.

One of the comforting regularities of bird behavior is its regularity. I kind of figured that she, and her mate, might return for more material, so I edged a little closer to the corner of the parking lot after the pair left. Sure enough, a few minutes later, I saw her approaching across the pasture. She swooped down to the gate again, eying me a bit longer than before. The male followed a few seconds behind, and once again perched above her in the walnut. I stayed in that spot for a half-hour or so, during which time the pair returned 5 more times to gather nesting material. Like clockwork. Nesting birds are fixated on their goal. Never did the male come down to the ground or do anything tangible to aid the female in her work. He just followed her around. But why?

She always perched on the gate first to check me out before dropping to the ground.

During the last couple of trips, she perched lower down on the gate on first approach.

The twig is just the beginning.

The entire load, twig and all.

In retrospect, it isn’t so surprising that the female flycatcher was highly fixated on a specific type of nesting material. One of the better-known peculiarities of great crested flycatcher nesting behavior is their compulsion to include a shed snake skin in the lining of their nest, which they build inside a tree cavity. Decades ago, when I kept way too many rat snakes as pets, I placed a shed skin of a yellow rat snake in my front yard, draped over one of the dead snags near my bird feeder. No more than an hour passed before I heard a pair of great crested flycatchers making a ruckus in the front yard. As I watched from my living room, the female flew to the snag, surveyed the skin for a moment, fussed with it for a minute or two, then unwrapped it and flew away with it. I was able to snag a couple of low-light photos through an open window. More importantly, I thought, I had discovered a way to get phenomenal close-ups of great crested flycatchers during breeding season. Simply bait them with a snake skin, yeah? I’ve never observed that response to a snake skin again, though I’ve tried it numerous times.

The female flycatcher from my DeLand front yard claiming her snake skin. Scanned from a transparency.

Why a snake skin? Some experimental evidence suggests that the presence of a snake skin deters visitation by flying squirrels, which can prey on the eggs and nestlings of the flycatchers.

So back to the question of the male’s role in all of these behaviors. Basically, he does nothing other than accompany the female. According to Cornell’s Birds of North America Online account of great crested flycatcher nesting behavior, males always follow the female around while she is building the nest, but never contribute directly to collecting materials or nest-building. So what is he doing?

Feeding of offspring by parents constitutes both parental investment and parental care.

Reproductive biologists make a distinction between the forms of time/resource/energy inputs into reproduction, labeled as parental investment vs. parental care. Parental investment refers to energy or resource expenditures by either parent that increase the chance of successfully reproducing, from the very beginning of the reproductive process (including formation of eggs and sperm) until the young have achieved complete independence. Parental care is a particular form of parental investment, and refers to time/energy/resources expended after eggs are laid or offspring are born. So the behaviors of both male and female in collecting nest material may be parental investment, but not parental care, since no eggs or hatchlings are yet present. The female’s nest-building behaviors contribute directly to offspring success, so there’s no question that her behavior constitutes parental investment. Females provide more parental investment and parental care than males in most bird species.

Male great crested flycatchers – what are they good for?

Here’s the question that’s bugging me – is the male flycatcher’s behavior during collection of nesting material really parental investment? The female’s behavior surely is, but do the male’s behaviors in any way contribute to nest building or the subsequent success of the offspring?

Eastern bluebirds are poster children for monogamy in birds, yet between 25-50% of nests have offspring sired by more than one male.

The alternative explanation is that the male is simply being selfish, protecting his own fitness. One of the remarkable findings of avian reproductive biology over the last several decades is the ubiquity and surprisingly high frequency of infidelity between what we have traditionally called monogamous birds. Although their basic social unit during the breeding season is the pair, in many or most songbirds, both males and females regularly cheat on their mates. In some species, up to 25% of the young in the population have been fathered by a male other than the bonded mate of their mother. Apparently there are no data on the frequency of extra-pair copulations or extra-pair young in great crested flycatchers.

So male birds are generally very attentive towards their mates during the period up until the eggs are laid. It takes only a minute or less for a female to pop a quickie with a neighboring male, so the bonded male must be constantly vigilant during this time. So is that the only reason he’s following her around? Stalking her, really. A rather different interpretation than the idea that he is somehow helping and protecting her during her nest-building phase. If the only purpose of his attendance is to prevent being cuckolded by his mate, then his activities aren’t really contributing to the success of the offspring at all. And what he is doing doesn’t constitute parental investment.

Loving, protective mate or jealous stalker? You be the judge.

The nomads return

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February 28, 2016

The idea of a nomadic lifestyle has great appeal to me, which is especially surprising considering what a homebody I am. On the infrequent occasions I take trips requiring more than a day, they are fully planned and orchestrated with all the precision an anal-retentive like me can muster. Still, the idea of packing a minimum of gear into a beat-up car and taking off on a whim across the country has long been a fantasy, albeit one I’m sure I’ll never attempt to fulfill.

Yellow-rumped warblers are able to winter further north than most warblers, in part due to their ability to feed on the fruits of waxmyrtle and digest the waxy coating as well as the pulp.

Among North American birds, perhaps the ultimate nomadic species is the cedar waxwing. So many aspects of the lifestyle and habits of these thoroughly charming birds are unique, and most are directly or indirectly related to the fact that it is one of the relatively few bird species on the continent that can truly be called a frugivore. Sure, lots of wannabes will take fruit opportunistically at times, sometimes relying heavily on it for their caloric needs for short to moderate lengths of time. The ability of tree swallows and yellow-rumped warblers to winter in great numbers farther north than other members of their clans, which mostly depend on insects for the greatest portion of their provender, has been attributed in part to their ability to subsist largely on the fruits of winter-fruiting shrubs such as bayberry. Both species have the unusual ability to digest the waxy coating of bayberry and waxmyrtle fruits, allowing them to survive periods when insects are hard to find.

Cedar waxwings in the pine flatwoods of Heart Island, feeding on the fruits of Ilex glabra, or inkberry.

Cedar waxwings, and the other two species of waxwing (Bohemian and Japanese) which collectively make up the entire family Bombycillidae, are true frugivores, depending almost entirely on fruit for most of the year. They do switch to a partial reliance on other foods in the spring and summer; in May, they rely heavily on flower buds, of all things, and later in the summer when they begin feeding nestlings they take a greater proportion of insects, necessary to provide the proteins lacking in most fruits.

The quest for fruits has led cedar waxwings to evolve a peripatetic lifestyle for all but those few months of the year when they must drop anchor to nest. Consequently, for bird photographers, and birders in general, they are a challenge to find at will, and a delight to see and photograph when found. As winter visitors to Florida, they are guaranteed to show up at some time or another between about October and May, but exactly when and where that will be is subject to a great deal of whimsy. For a bird photographer to state with any sense of confidence that I’m going to photograph waxwings today is a proclamation as foolish as planning to win a Powerball drawing. Unless he or she happens to be looking at them at that very moment. Here today, gone an hour later.

Waxwings in northern Virginia, on their breeding ground, feeding on mulberry, Morus rubra.

Ornithologists concerned with classifying patterns of bird movement express hesitation at calling waxwings migrant, though they do show regular patterns of southward and northward movement at a broad scale, at the appropriate times of year. Those movements, though, do not begin to approach the level of regularity and predictability of most true migrants. They show relatively low levels of philopatry in the breeding season; in other words, unlike many birds, they don’t tend to return to the same breeding areas year after year, and during the winter their movements seem to be completely irregular and unpredictable. Both of these characteristics are related to their reliance on fruit, which is itself somewhat unpredictable in time and space, and once found, subject to rapid depletion once big flocks of frugivorous birds discover it.

A cedar waxwing pair passing a piece of fruit back and forth, part of their courtship and pair-bonding ritual.

The ability of big flocks to rapidly consume most or all of the fruit in an area is one of the most appealing aspects of their behavior. Watching a writhing, swirling mass of lovely pastel-colored birds attack a mass-fruiting holly or cherry tree and pick it clean within a few minutes is an amazing sight. Part of the appeal of that behavior is the furious and fanatical way they conduct their feeding frenzies; birds are constantly moving into and out of the fruiting tree, plucking a few fruits and quickly departing to perch nearby before the next foray. The result is often a maelstrom of activity that can be over and done with in the blink of an eye. Followed by the departure of the flock to parts unknown, seeking their next meal.

Trees full of large flocks of waxwings are one of the most welcome sights of winter.

Waxwings have been less abundant this season than my notoriously untrustworthy memory suggests they usually are. Some winters between January and February, they descend on DeLand in huge numbers, with flocks numbering in the thousands. For the few days or weeks they are around, it’s hard to miss the big roving groups bopping around town devouring every fruit in sight. One morning they might be devouring the fruits of sabal palms in the parking lot of the Publix where I shop, the next at a yaupon hedgerow near a strip mall. A few years ago, huge flocks were on the Stetson campus for several days in a row; one morning on my way to my office, a flock of hundreds was feeding and drinking around the Gillespie museum, and I spent a delirious hour or so photographing them. Students in my Intro Biology II class were subjected to 15 minutes of my rantings about and photographs of the waxwings that morning, exhorting them to be on the lookout for these wonderful wanderers over the next few days. I have no idea whether that rant led anyone in that class to give even a second thought about waxwings afterwards; probably to them the most salient fact about my waxwing rhapsody was that it wouldn’t be covered on the next test. Another morning, as I was driving through the new development next to the one I had just moved into, I photographed a small flock of waxwings beefing with a group of robins over a few drops of water beaded atop an electrical junction box. To photograph waxwings requires eternal vigilance.

Waxwings and robins competing for space and a few droplets of water atop an electrical junction box.

Congregation of waxwings at a sidewalk puddle on the Stetson campus.

Last Sunday afternoon I was drifting in and out of a mid-afternoon stupor when I was awakened by the wick calls of a couple of robins in the backyard. Robins shifted into their urban phase several weeks ago, and have been fairly common in the neighborhood and around DeLand. The presence of flocks of robins indicates the possibility of waxwings in the area – the two often travel together, and feed together at mass-fruiting plants. I had only seen waxwings in my neighborhood a couple of times so far, though, and none had been feeding. I have several large wild cherry trees with large fruit crops I had been keeping my eye on, and though I had seen robins feeding at them several times, they were never accompanied by waxwings. Soon after I heard the robin calls, one of them flew down to the birdbath, soon to be joined by another. And then I heard the high, quavering seeee calls of a couple of waxwings, and I was instantly wide awake. I happened to have my camera with big bird lens on the couch beside me, and was ecstatic when a pair of waxwings joined the robins at the birdbath. I fired off a couple of record shots, and then the birds spooked and took off. Soon they were back, accompanied by a half-dozen or more additional waxwings, and they and the robins spent the next three or four minutes bathing and occasionally sparring for position. I eased out the back door onto the enclosed patio, and was shooting nearly non-stop the entire time they were there. Hoping like hell that all the settings were right, because I had no time to stop and chimp my shots to ensure I wasn’t making some major bonehead mistake.

The robin at the birdbath alerted me to the possibility of waxwings.

Though they have their occasional spats, peaceful coexistence between the robins and waxwings is possible.

Soon, though, something signaled the waxwings it was time to move on, and they departed en masse, trilling as they winged away. I haven’t seen them in the neighborhood since, and may not again this winter. And that’s okay. They graced me with their presence and gave me reasonable photo opportunities for a few minutes, and for that I’m thankful. See you next year, my friends. I hope.

Nemesis no more

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June 15, 2015

Every serious bird photographer who has been at it for a while has a nemesis bird or three. There’s a progression for the obsessed bird photographer – first you knock out all the easy stuff. You know, feeder birds, extremely common and cooperative stuff like yellow-rumped warblers, turkey vultures, ring-billed gulls, and so on. At some point, for many of us, then the compulsion turns into a quest to photograph all the birds of the region you spend most of your time in. An unattainable goal for most, but a tangible target nonetheless. Gradually the library of images grows, until you have acceptable images of most of the typical species. It’s a moving target, though; one problem is that the definition of acceptable is constantly changing as your proficiency increases (hopefully). So while your biggest pleasure is photographing a species that you have no images of, you’re constantly trying to upgrade the quality of the images of those species already photographed. And so it goes. You accept that the very rare or elusive species are distant dreams at best, but every now and again that improbable event occurs and you actually add one or two of those to your collection of bird images. Why do we do it? That’s a whole other question I’m not about to try and tackle; I really don’t understand it myself. It does take on aspects of mental illness after a while, though. How many hundreds of images of northern parulas and great blue herons do you really need? The only answer I’ve ever arrived at is more.

As beautiful as they are, some birds, like northern parulas, are just too easy to photograph to be a real challenge.

More vexing than the rare species though are the nemesis birds. Those are the species that aren’t particularly uncommon or hard to find, and of which you can find thousands of high-quality images on-line, yet they somehow elude your best efforts to add them to your list. The degree of consternation inflicted by these recalcitrant bastards is directly related to how long you have pursued them. In some cases it may be decades.

I have dozens of images of the larger American bittern that I’m pretty happy with; least bitterns are a different story.

For me, one of the nemesis birds that has been at the top of my list for the decades I’ve lived in Florida is the least bittern. These elegant little birds, the smallest of the North American herons, are widespread as breeding birds in the ubiquitous wetlands of Florida. They occur as far north as Virginia, where I cut my birding and bird photography teeth, but I never saw them there. But in Florida, they are not difficult at all to find, or uncommon. Breeding densities as high as 15 pairs per hectare have been recorded. They do tend towards the skulky end of the behavioral continuum, though, which combined with their small size (12-14”, not much larger than a blue jay), can make them a bit of a challenge to photograph. But seeing them – hell, I see them all the time during the breeding season in the appropriate habitat. During the 7 years I did weekly bird censuses at Emeralda Marsh Conservation Area in Eustis, which contains lots of good breeding habitat, I saw them regularly between mid-March, when most return from their winter home, and mid-October, when most of them have departed. During mid-summer, I would often see or hear 5 or more of these charming little waders on each census. Their departure each year, in which I once again failed to obtain a decent photo, always brought a bit of anguish, and a bit of hope that next year would be the one. An occasional oddball individual will overwinter in central Florida, but for the most part they are the typical birds of summer. By which I mean Florida summer, which runs from about March to October.So I never really entertained any illusions of photographing one outside of the breeding season.

Seasonal abundance of least bitterns at Emeralda Marsh Conservation Area, near Eustis FL.

This is no great blue heron, posing in every roadside ditch for any yokel with a point-and-shoot. (No offense to the yokels with point-and-shoots out there.) You have to go looking for them, and then you have to find one close enough (which is pretty damned close for a bird that small) and exposed enough for a decent photo. Needless to say, that particular set of conditions eluded me for so long. Oh, sure, I got photo ops on occasion. I have several dozen transparencies (also called slides, for those digital natives unfamiliar with the concept of film) with recognizable least bitterns on them. But in all, they are small in the frame, and none of them captured the essence of least bittern.

Seriously, any twit with a pinhole camera can get stunning closeups of great blue herons in Florida. Which is not to say that I don’t still photograph them on occasion. What can I say – I’m a high-tech twit.

These are amazing little birds to watch, if one is fortunate enough to see one foraging for any period of time. On the continuum of foraging strategies of herons and egrets, ranging from the nearly immobile ambush foragers like great blues to the maniacal pursuit foragers like reddish egrets, least bitterns are somewhere in the middle. They can be frozen for extended periods, intensely peering at a couple of square inches of habitat until a prey item comes into range, but they can also be relatively active, changing perches every minute or two until they find the right spot. Acrobatic little fuckers they are as well, hanging upside down from a narrow perch above the water, extending their telescoping necks in an instant to snag the dullard mosquitofish that fails to notice this pendulous beauty.

That’s some neck serious neck extension.

So yeah, I have a handful of old, mediocre images of least bitterns, a couple of which I thought were pretty decent at the time I took them. The advent of the interwebs totally recalibrated my concept of what constitutes a decent image, though. Once I began seeing the high-quality images so many other photogs were able to obtain of this handsome little heron, my evaluation of my own images plummeted. One of my favorite images, at the time, was of a recently fledged youngster sitting on his haunches in the middle of Airstrip Road, surrounded by shellrock, with a few wispy tufts of down feathers still remaining on his adorable little noggin. But this slide, like all my others, failed to meet one of my prime criteria for a good bird shot – you need a level of resolution allowing discrimination of barbs of individual feathers. My old slides all failed that test.

One of the best of my least bittern shots from the film era. Lacking in so many ways.

My favorite film image of a least bittern – a slightly out-of-place, befuddled looking youngun.

Even after I went digital, which makes bird photography an order of magnitude (at least) easier than the primitive film technology, good least bittern images still eluded me. I made a couple of trips during the breeding season to the celebrated Viera Wetlands in Brevard County, a site from which I had seen dozens of superb least bittern photographs posted on-line. I saw them there, but never got anything approaching the type of image I had in my mind.

I was moderately satisfied with this “in-habitat” shot of a least bittern from Viera Wetlands, but it wasn’t really what I was hoping for.

The closest I had come to a satisfactory close-up of a least bittern prior to yesterday’s outing, also from Viera Wetlands.

So I’m pleased as punch, as the happy warrior Hubert H. used to say, to report that my quest for decent least bittern photos has turned the corner. I’m also happy to report that this happened at my new favorite bird photography site, the Lake Apopka Restoration Area wildlife drive. On my first visit a few weeks ago, I thought this magnificent site should be full of least bitterns, but didn’t actually see or hear any until my second or third visit. A couple of weeks ago I actually got some marginally acceptable ops with a least bittern perched in a willow tree. The photos were by far better than anything I had previously, but the light was less than optimal (a totally overcast morning, the bird strongly backlit by a featureless white sky), and it was a bit too distant to reveal the kind of plumage details I consider requisite for a good bird photo.

Least bittern in a willow, from Lake Apopka Restoration Area.

Show me what you can do with that neck.

Yesterday, my chakras aligned. The bird gods smiled. I got lucky. Interpret it as you see fit. It was a sunny morning, bird activity was everywhere along the wildlife drive, and around 8:00 a.m. while the morning light was still sweet and rich, I spotted a least bittern feeding from some dead stems of some emergent woody plant in a shallow impoundment. And it was relatively close to the road. Somewhat incredulously, I slow-rolled towards the little dude, expecting it to bolt into deep cover long before I was in photo range. But he didn’t. I slowly pulled up to where he was feeding, with the light coming from directly behind me (point your shadow at the bird, says the bird photog guru Artie Morris), and he cared not a whit. Heart pounding, adrenaline pumping, I feverishly began photographing. After a minute or two, the least beast decided to move, flying to a new perch 30 or so yards behind me. But still close to the road. I backed up slowly, and once again he stayed for a few moments, allowing a few more shots as he moved from perch to perch before finally disappearing into dense cover.

The first excellent photo op of the morning.

I particularly liked all the carnivorous bladderwort plants in flower below this leastie.

Full neck extension.

One parting over-the-shoulder look before he disappeared into the veg.

I was totally juiced. It’s fair to say that if I hadn’t taken another photo or seen another bird that morning, I would have considered it a morning very well-spent. As I drove on along the wildlife drive, I was savoring the moment when I could look at those images on the big screen and begin editing them. There’s something incredibly rewarding about capturing even one series of decent images relatively early in the morning; it doesn’t really matter what the rest of the day brings. You know you already have some images you’re going to be pleased with. Of course there’s always that bit of the neurotic in me that begins the second-guessing game – what if I did something wrong, or missed critical focus? Even after chimping the images like a demented fool my fears are never completely allayed. You can only judge image quality so far by viewing them on the LCD screen of the camera. You have to download them and view them large to really make an accurate assessment.

Cooperative least bittern number two. Even closer than the first.

Cooperative least bittern number two, perched on one leg, with the other tucked up into his belly feathers. Even closer than the first.

So I was a pretty contented dude at that point. But that wasn’t to be my only bittern buzz of the day. Not more than 15 minutes later, I spotted another, sitting completely exposed on a dead branch, in perfect front light. Even closer than the first. And once again, I was amazed as I slowly rolled up on him and he sat perfectly still. I shot this guy for 4-5 minutes as he mostly did nothing other than check me out occasionally. At one point he dropped the foot that he had tucked into his belly feathers, turned around, hunched forward, and expanded his throat and chest as he began calling with the sweet cuckoo-like call that is the easiest way to detect the presence of these tiny ardeids. I was in a state of absolute euphoria as I filled a memory card. Hundreds of images varying only in the slightest degree, the vast majority of which would never be seen by anyone like me. But what did I care? A nemesis bird had been forever removed from the list.

A vertical shot, still on one leg. When you’ve got a bird posing for you like this, it’s hard not to go batshit crazy.

Eyeballing me under the chin, a charming behavior of the least bittern.

Turned around, throat puffed out and calling. One of the last shots in the series.

Can the crested caracara be far behind?

Image Gallery: Return to Lake Apopka Restoration Area

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The yellow flowers blanketing this pool are bladderworts, Utricularia sp., a carnivorous plant. I’ve never seen a concentration of bladderwort like this.

May 18, 2015

All images are linked to larger versions.

I couldn’t help myself. I visited the new wildlife drive at Lake Apopka Restoration Area again yesterday, and though the light was miserable for photography for the first couple of hours, the wildlife was there. Here are some of my favorite shots from the morning.

Recently fledged great blue heron.

Bullfrog feeding a mosquito. Look closely under his right eye.

Common moorhens and their broods were once again one of the most entertaining sights.

Common gallinules and their broods were once again one of the most entertaining sights.

Sorry, bro, you cannot pass.

This osprey was sitting atop a leaning pole trying to eat his fish.

This osprey was sitting atop a leaning pole trying to eat her fish.

She was repeatedly harangued by this boat-tailed grackle, who bum rushed her several times.

Why? Eventually the osprey moved on, and the grackle took top spot and cleaned up on the fish scraps.

Least bittern in the willows. You don’t appreciate how long their neck is until they stick it out.

A more typical view of a least bittern.

Green herons were abundant, but very shy. This one allowed me one shot before taking off.

A juvenile little blue heron showing high breeding colors in the cere and base of the bill. Yearling birds in juvenile plumage will sometimes breed in this species.

Not a bad day for herps. This Florida green watersnake (Nerodia floridana) was basking in the dead cattails as the sun struggled to make an appearance.

That’s one chilled out baby gator.

A big female soft-shelled turtle (Apalone ferox) mucking around in the shallows.

Pig frog (Lithobates grylio) surrounded by several floating aquatic plants, including Lemna sp., (duckweed), Salvinia minima (water spangles), and Azolla filiculoides (American waterfern; not a fern).

Eastern kingbird. I don’t see this species often in central Florida except as a migrant in passage. This bird is probably a breeder.

I saw a half-dozen or so limpkins.

These two great blue herons were arguing over territorial rights, using the head up-wing droop posture that says get the hell out of my space.

By mid-day, it was getting quite toasty. Barn swallows were basking on the hot shell rock roads, overheating to the point that they were panting to cool down. Why? Probably to kill ectoparasites with the heat load.

Anhinga performing gular flutter, a heat-dissipating behavior.

A splendid morning in the wetlands

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Black-necked stilt snags a mosquitofish

Click on any image to see a larger version.

May 10, 2015

On Friday I visited the Lake Apopka Restoration Area’s newly opened 11-mile North Shore wildlife drive for the first time. To say that I was impressed with the wildlife viewing opportunities there would be a massive understatement. This area will surely become one of my regular destinations for natural historizing and photography in coming years.

When I was a graduate student at the University of Florida in the 80’s, I remember hearing of the incredible birding opportunities in late summer at the Zellwood muck farms. I never made the drive to check the area out. I should have. My first visit to the north shore area of Lake Apopka came in the fall of 1998, when I was checking out potential field trip sites for the Ornithology class I was teaching that fall at Stetson. From DeLand, it’s less than an hour’s drive, mostly through bucolic mixed agricultural habitat in Seminole County. I distinctly remember driving down one of the shell rock roads, surrounded on both sides by browned, fallow vegetation with little evidence of the legendary concentrations of migratory birds I had come to see. A couple of times I saw small groups of aquatic birds, including some waders and terns, flying past me towards the west. Encouraging. Then I topped a small rise that allowed an overview of one of the flooded fields that acted as the great bird attractors, and I nearly ran off the road at the stunning sight of hundreds of acres of shallow water fields teeming with aquatic birds of every stripe. Tons of waders, including hundreds of great blue herons, white pelicans, other egrets and herons, wood storks, and a panoply of smaller birds including shorebirds, terns, anhingas… I was ecstatic. I made several visits to the area in the next couple of weeks, and then the St. Johns Water Management District closed the whole area to public access. Dead birds started showing up by the hundreds.

Most of the habitat in the Lake Apopka Restoration Area is highly disturbed, consisting of former agricultural fields that are converting back to a variety of marsh habitats.

The vast wetlands fringing Lake Apopka, a 30,000-acre lake that is Florida’s fourth largest, had been heavily farmed since the 40’s, and the “muck farming” operations devastated the water quality in Lake Apopka and its surrounding highly modified wetlands. These farming operations left behind miles of levees, roads, canals and pumping systems to move lake water onto and off of the agricultural fields that had been formed by draining the natural wetlands. After spending nearly $100 million between 1996 and 1999 to buy out about 13,000 acres of former farmland, the St Johns River Water Management District began major restoration efforts in the mid-90’s. Restoration plans for the area featured a 760-acre flow-way designed to circulate highly eutrophic lake water through restored wetlands in order to filter out excess nutrients and pollutants, and also included the flooding of large tracts of farmland in the fall of 1998 in the Zellwood farming district. The Zellwood muck farms were legendary for years among Florida birders for their late summer and fall concentrations of shorebirds. Large numbers of sandpipers, plovers, gulls, terns and other aquatic birds would congregate in the temporarily flooded fields in late summer to feed and prepare for the rest of their migration. During the farming era, however, these fields were drained and planted with winter crops by November, and whatever birds remained in the area moved on.

Canals and water control structures permeate Lake Apopka Restoration Area.

In fall of 1998, the management plans for the area called for prolonged flooding of some of these fields, and the response by the avifauna was incredible. Between August 1998 and February 1999, local bird groups and district scientists documented over 111,000 individual birds using an 8000-acre area. Flocks of tens of thousands of teal, diving ducks, and American coots were present at times. Beginning in November, however, dead birds began to appear on the site. White Pelicans were the hardest hit; at one time, the white pelican flock at Zellwood numbered over 4000, believed to be nearly half of Florida’s wintering population of these huge, lumbering birds. By February of 1999, nearly 500 bird deaths had been recorded on site, and another 500 or so dead birds, mostly white pelicans, were found throughout Florida, and were suspected to have originated from the Zellwood area. Also affected were smaller numbers of wood storks, an endangered species, along with great egrets and ring-billed gulls. I remember watching a juvenile wood stork at Lake Woodruff National Wildlife Refuge in DeLeon Springs for several days in a row during January 1999, some 40 miles away from Lake Apopka. That bird moved fairly slowly, was quite tame, and stayed in the same restricted area for the entire time I observed it. Nearly a week later, I found the carcass of a wood stork near where I had seen that curiously behaving bird. I still have the skull on a shelf in my office.In retrospect, I suspect that it was also a Zellwood bird.

Ospreys were abundant on this lovely May morning, especially in the parts of the drive closer to Lake Apopka.

The catastrophic bird mortality took everyone involved with the project by surprise. Although extensive sampling of the acquired lands was done before flooding to determine if there were any contamination hazards, the assays failed to turn up anything that looked like a threat to the health of the birds. In February 1999, the flooded fields were drained to encourage the birds to move elsewhere, and extensive soil and water sampling was performed, along with necropsies of many of the dead birds to attempt to determine the source of mortality. A period of uncertainty and debate about the source of the bird kill ensued, during which a variety of hypotheses, including pesticide contamination and epidemic outbreaks of avian cholera and Newcastle’s disease, were proffered. Eventually, acute toxicity due to exposure to multiple pesticides (toxaphene, Dieldrin, DDT) was identified as the most likely cause, and the restoration/remediation plans for the Apopka North Shore Restoration project were modified accordingly. Apparently, a concentrated “hot spot” of discarded pesticides on a restricted area of the north shore property was responsible for all of the problems. Amazingly, the pesticides involved had been banned and out of use for 10-30 years.

This boat-tailed grackle was engaged in “gaping behavior”. They insert their beak into some substrate and open it to push aside obstructions. Many icterids use this behavior to find soil invertebrates, but this male was using it to open a little hole in the duckweed through which he could peer down into the water.

The target? Snails. He deftly pulled them out of the shell and enjoyed fine dining even without the garlic butter.

For the next decade, as mitigation and clean-up efforts proceeded, most of the North Shore area of Lake Apopka was mostly off-limits to the public. One of the mitigation techniques used to deal with the elevated concentrations of organochlorine pesticides and excessive nutrients that had accumulated from decades of farming was a method called soil inversion. Modified agricultural equipment was used to plow down to a meter or more into the heavily contaminated top layer of soil and flip it over, replacing it with deeper layers of clean soil.

The vegetational composition of the wetland habitats is highly variable. Many areas are dominated by cattails, usually an indicator of high nutrient levels (eutrophication).

Restricted access to the public ended in 2014, when the SJRWMD began opening some of these north shore properties, easily accessible due to the extensive networks of diked roads, to the public for hiking and biking. The North Shore Wildlife Drive opened on Friday, May 1. It is open from sunrise to a half-hour before sunset on Fridays, Saturdays and Sundays year-round.

Waders of all types were common, including great and snowy egrets, great blue, little blue, tricolored and green herons, and a few black-crowned night herons. This bird is an immature.

Little blue herons and green herons were probably the two most common waders I saw.

Green herons were omnipresent, but a bit skittish. Not many photo ops for these shy guys.

I wasn’t expecting huge numbers of birds or great diversity on this visit; wintering birds have largely left the state, and the passage of transient migrants is rapidly winding down. It’s that time of year for Florida birders when diversity is plunging to its summer nadir. Still, I was hoping there might be a few bobolinks around, and perhaps some other lingering migrants. I wasn’t disappointed. Almost as soon as I entered the drive, I heard, then saw a small flock of bobolinks in the marshes north of the drive. Too distant for photography, but it didn’t matter. Much. I love seeing and hearing bobolinks, anytime, anywhere, at any distance. The first stretch of the drive heads due west, so the sun was directly at my back and the habitat on either side was strongly side-lit. Not the best conditions for bird photography, but still I was impressed by the dozens of herons, egrets, ibis, limpkins, and other aquatic species foraging in the canal paralleling the drive. And the marshes were full of singing icterids on territory – red-winged blackbirds and boat-tailed grackles. So I was a little bummed out by the lack of photo opportunities in the first couple of miles of the drive, but there was so much bird life around that it didn’t feel right to be disappointed. In addition to the waders in the canals, several black-bellied whistling ducks and a couple of mottled ducks did flyovers, along with lots of waders. Barn swallows were coursing low over the marshes throughout the morning.

Common gallinules were abundant, including numerous pairs tending to their broods of newly hatched fuzzballs.

This half-grown juvenile common gallinule was all by his lonesome. Perhaps the only surviving member of his brood.

Common gallinules are attentive parents. This one was teaching her youngster how to preen.

How do I look, Mom?

Feeding the babies.

About two miles in, the drive reaches the shore of Lake Apopka and a large, historic pump house remaining from the agricultural period. On a small, drying pond near the pump house, I found a black-necked stilt, solitary sandpiper, and least sandpiper feeding in the shallow water and muddy shoreline, directly front-lit by gorgeous early morning light. As I spent the next 20 minutes or so burning up my memory cards on these photogenic birds, my slight dudgeon lifted. This is what I had come for.

Black-necked stilts are very active foragers, frequently submerging their entire head searching for prey.

Like this.

Got one.

The rest of the morning followed suit. Though the birds were mostly breeding residents, it mattered not. Common gallinules, various egrets and herons, blackbirds, including a couple more small flocks of bobolinks, barn swallows (along with a few tree swallows in one flock), and other birds were everywhere. In one of the canals paralleling the drive, I was shocked by the huge numbers of big frogs half-submerged in duckweed and Salvinia, occasionally making short leaps to capture prey. Both bullfrogs and pig frogs were calling, which was somewhat surprising to me. I had always thought of those two species as ecological equivalents that didn’t normally co-occur. I don’t know where I picked up that bit of dubious knowledge, but clearly it doesn’t apply to the big Lithobates (could it be true that this horrendous genus is about to be decommissioned and the members of this genus placed back into Rana, where they belong? Joy.) frogs of the restoration area.

While shorebirds weren’t particularly diverse, and I only saw a few individuals of any species, it was still nice to see killdeer, stilts, spotted and solitary sandpipers, and several of these tiny little least sandpipers.

Solitary sandpiper

Solitary and least sandpiper

With all of those frogs, I figured there must be tons of snakes to prey on them, but I saw no water snakes or other aquatic serpents. A couple of black racers crossing the road were the only snakes I saw on this morning, but I’ve got to think the frog-eating aquatic snakes are there somewhere. Another time.

Bullfrog (Lithobates or Rana catesbeianus)

Pig frog (Lithobates or Rana grylio)

The bullfrogs were freaking thick!

Besides the frogs, the other herps seen included lots of gators, a couple of black racers, and this cute little striped mud turtle (Kinosternon bauri) who looks like she just finished laying eggs.

And there certainly will be other times. I can barely wait until August, when the vanguard of fall migrants will begin to appear in numbers. I’m particularly excited about the potential for big numbers of yellow warblers, which I haven’t seen aside from an occasional lone individual or two since I stopped doing bird censuses at Emeralda Marsh Conservation Area. In August and September I sometimes found hundreds of yellow warblers a day in the willow thickets along the levee roads. There’s an abundance of similar habitat along the wildlife drive at Lake Apopka.

The best part of the day? In the 4 hours I spent there, I saw only one other car. I wish it would stay that way, but I know it won’t. The area is too amazing to remain a secret for long.

A quick trip to the parking lot of the North Shore trailhead at the end of Duda Rd. produced this lovely indigo bunting.

For more information about the North Shore Wildlife Drive, go to http://www.sjrwmd.com/recreationguide/lakeapopka/

Images: Eastern Diamondback Rattlesnake

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March 3, 2015

I was fortunate to be able to photograph this yearling eastern diamondback yesterday. All images are clickable to view larger versions.

Volusia Naturalist

A celebration of natural history

Thrush passages

December 30, 2016

Of crows, cats and the preservation of sanity

November 11, 2016

What was that snake thinking?

September 6, 2016

References

DeVault, T. L., & Krochmal, A. R. (2002). Scavenging by snakes: an examination of the literature. Herpetologica, 58(4), 429-436.

Mullin, S. J., & Cooper, R. J. (1998). The foraging ecology of the gray rat snake (Elaphe obsoleta spiloides)-visual stimuli facilitate location of arboreal prey. The American midland naturalist, 140(2), 397-401.

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.

Daddy duties

June 1, 2016

The nomads return

Nemesis no more

June 15, 2015

Image Gallery: Return to Lake Apopka Restoration Area

May 18, 2015

A splendid morning in the wetlands

May 10, 2015

Images: Eastern Diamondback Rattlesnake

March 3, 2015

December 30, 2016

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November 11, 2016

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September 6, 2016

References

DeVault, T. L., & Krochmal, A. R. (2002). Scavenging by snakes: an examination of the literature. Herpetologica, 58(4), 429-436.

Mullin, S. J., & Cooper, R. J. (1998). The foraging ecology of the gray rat snake (Elaphe obsoleta spiloides)-visual stimuli facilitate location of arboreal prey. The American midland naturalist, 140(2), 397-401.

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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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June 1, 2016

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June 15, 2015

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May 18, 2015

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May 10, 2015

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March 3, 2015

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