Monthly Archives: December 2013

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Graded signals

Orange-crowned warbler.

Orange-crowned warbler.

December 28, 2013

A number of common Florida birds are named for features that are rarely seen.  Ring-necked ducks, ruby-crowned kinglets, and bristle-thighed curlews come to mind.   This morning I was relaxing on the patio, savoring my best Christmas present, Joe Hutto’s endearing Illumination in the Flatwoods: A Season With the Wild Turkey.  I watched and listened as numerous flocks ranging from a few to several dozen American robins flew over regularly; it seems that they are beginning to shift to their urban phase.  While totally mellowing on this gorgeous gray Florida day,  I was fortunate to not only see, but also photograph a feature of one of these common Florida birds that I’ve seen only a few times.  Ever.  The orange crown of an orange-crowned warbler.  (If you’re still scratching your head about the bristle-thighed curlew reference above, give yourself a pat on the back; it’s a joke.  I’ve never seen one, in Florida, Hawaii, or elsewhere.)

Ruby-crowned kinglet, showing no sign of a ruby crown.

Ruby-crowned kinglet, showing not a hint of a ruby crown.

A low-intensity display of the ruby crown.

A low-intensity display of the ruby crown.

Many birds have plumage or structural features that serve as signals of some sort, and which can be widely variable in strength, or even their presence or absence.  These graded signals allow nuance in communication between individuals.  Exactly what is being communicated is often (usually?) hard to determine.  Ruby-crowned kinglets have been tormenting me for years in my quest to photograph the full blown crest erection.  Haven’t come close; a patch of red laid flat along the crown is the best I’ve been able to manage so far.  I see ruby-crowns displaying their brilliant crest often enough that I have some intuition of its message – it seems to be an aggressive display towards conspecific males, and the degree of piloerection is an index of level of bad intent.  Males will occasionally flare their crest in response to playback of ruby-crowned kinglet vocalization (though not while mobbing, suggesting it is a signal for conspecifics), and when interacting in chases and aggression with other males.

One of the more nondescript of Florida's winter warblers, if it doesn't show any prominent field marks like wing bars or head pattern, it could be an orange-crowned warbler.

One of the more nondescript of Florida’s winter warblers, if it doesn’t show any prominent field marks like wing bars or head pattern, it could be an orange-crowned warbler.

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In orange-crowned warblers, I’ve seen even a smidgen of the orange so few times that I have no idea when or how they deploy their display.  A Google image search for orange-crowned warbler returns a ton of very nice images, but only a handful show any sign of the orange crown.  And most of those are birds being held in the hand.  My inference is that orange-crowned warblers never flare the crown to the degree sometimes seen in a highly agitated ruby-crowned kinglet, in which the red cap looks more like a mohawk than it does plumage.

Northern cardinal male with flattened crest.  What signal is being sent, and to whom?

Northern cardinal male with flattened crest. What signal is being sent, and to whom?

A more typical crest position.

A more typical crest position.

Feather position alone can act as a graded display, with or without display of normally hidden color.  The degree of elevation of the crest on a northern cardinal changes dramatically, occasionally disappearing entirely when an individual is alone and presumably totally mellowed out.  For cardinals and blue jays, the erect crest is the default state.  For many other “uncrested” birds, the flathead is the default state, and a prominent crest is displayed only briefly and infrequently.  Think green heron here.

Chill green heron.

Chill green heron.

Mildly perturbed green heron.

Mildly perturbed green heron.

Seriously pissed off green heron.  Not surprisingly, it's a teenager.

Seriously pissed off green heron. Not surprisingly, it’s a teenager.

In other birds, the signal is always visible to some degree, but that degree varies tremendously.  Male red-winged blackbirds sometimes throw me for a loop when I see them with their orange and yellow epaulets nearly totally concealed by other feathers.  If I miss the sliver of yellow visible, I’ll begin to try and turn the bird into a more uncommon blackbird.   At full display in a singing male, the epaulets are like brilliant orange-red flames.

Red-winged blackbird trying to conceal his true identity.

Red-winged blackbird trying to conceal his true identity.

Full display.

Full display.

Though I almost never see their orange crown, I see orange-crowned warblers fairly often, usually as single birds traveling with mixed-species winter flocks that can include titmice, chickadees, yellow-rumped warblers, kinglets, gnatcatchers, and small numbers of a half-dozen or more small passerines.  I love mixed-species flocks.   Orange-crowneds are one of the latest of the wintering warblers to migrate into Florida;  while doing my Emeralda bird surveys, they usually didn’t appear until the third week of October or the first of November.  Between then and their departure in late March (late entry, early exit), I saw on average 2-4 birds per census.  Rather slow, deliberate leaf-gleaners for the most part, in low- to mid-level vegetation.   They seem to like to investigate clumps of dead leaves.  I once photographed one at Merritt Island NWR feeding on a large inflorescence of the flowering vine Mikania scandens; it was feeding on insects attracted to the flowers as well as on floral nectar.  Orange-crowned warblers will puncture the base of some long-tubed flowers to gain access to the nectar.  Seems like a very tropical behavior to me, though many of these birds will remain in the mild but temperate southeast for the winter.

Checking out the dead leaves.

Checking out the dead leaves.

 

Nectaring and gleaning at Mikania scandens

Nectaring and gleaning at Mikania scandens

Feeding on nectar/pollen of willow.

Feeding on nectar/pollen of willow.

Through most of the winter in Florida, the orange-crowned warbler is a very reliable bird, though I never see them in large numbers.  I once saw a small flock of 4 traveling together in my backyard; they were leaf-bathing on a drizzly February afternoon in the wet foliage near the top of a big Senna bicapsularis.  I saw a hint or two of the orange crown on that day as well.

Seasonal abundance at Emeralda Marsh Conservation Area, Lisbon FL.

Seasonal abundance at Emeralda Marsh Conservation Area, Lisbon FL.

Leaf bathing in Senna bicapsularis

Leaf bathing in Senna bicapsularis

The bathing orange-crowned today was taking the more formal soak and fluff in the birdbath, and I was able to watch him (only males have the orange crown, which probably says something about its function) for a couple of minutes.  The orange crown was frequently visible, though it was probably coincidental to the normal feather fluffing and puffing that bathing birds do.  There were no other orange-crowned warblers, or birds of any other species that I was aware of, nearby that this little guy might have been signaling to.  Perhaps the relatively low population density of orange-crowned warblers accounts for some of the rarity of the display, especially when compared with the somewhat similar appearing ruby-crowned kinglets, which are typically much more abundant than orange-crowneds, and which often occur in larger numbers in mixed-species flocks.

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I have to think even a highly enraged orange-crowned warbler’s display is still pretty subdued.   The species account at Cornell’s Birds of North America Online has this brief tidbit (from Arthur Cleveland Bent’s monumental multivolume set of life histories of North American birds) about the orange crown display:  “Male threat or alarm display can involve elevation of head feathers to display (barely) the orange crown patch (Bent 1953).”  As graded displays go, the orange-crowned warbler’s is quite modest.  So why does it give me such a thrill to see it?

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An early Christmas gift

PABU_12202013-35_620 COCDecember 21, 2013

On Friday, December 13, a male painted bunting showed up at one of my feeders.  Whatever vestiges of superstition I might harbor about that particular date should be forever banished by his appearance.  It’s one of the luckiest days for me in recent memory.    One of my most intense hopes for the winter bird season had been just this event.  Others include big flocks of cedar waxwings swarming around the dahoon holly now fruiting in my yard, decent portraits of the sharp-shinned hawk that  periodically strafes my feeders, the  sharp-shinned hawk perched with a just-captured painted bunting grasped in his talons… well, maybe not the last one, though that would be a spectacular image.

I’ve lived in my current home for a little over 5 years, and in that time I’d guess I’ve seen painted buntings here 15-20 times.  They aren’t uncommon birds when they’re in central Florida during  their non-breeding season.   But they are hard to see, particularly considering how spectacularly apparent (seemingly) the adult males are.

Seasonal occurrence and abundance of painted buntings at Emeralda Marsh Conservation Area, Lake Co. FL

Seasonal occurrence and abundance of painted buntings at Emeralda Marsh Conservation Area, Lake Co. FL

In the seven years I did weekly bird censuses at Emeralda Marsh Conservation Area in Lisbon, FL, I saw painted buntings regularly between late July and late April.  During January, on a few occasions I saw 4-6 individuals in one day.

A greenie; a female or immature male painted bunting.

A greenie; a female or immature male painted bunting.

Of those maybe 20 sightings of painted buntings around my house, fewer than half have been adult males.  More common are the “greenies”, the females and immature males that are uniformly citrusy green.  Lovely birds in their own right, but they can’t hold a patch to the males.    Of the fewer than 10 males I’ve seen, more than half were seen within the first year I lived here.   The frequency with which I see both males and females has declined noticeably in the last few years.

The reason is simple – habitat.  Big patches of habitat are better bird attractors than smaller patches.  When I bought my house in 2008, the 50-odd acre tract directly behind it was natural habitat – mostly successional oldfield where a fernery used to be, but also including a small grove of several dozen orange trees.  The oldfield habitat was in the woody invasion stage of succession, dominated by grasses and forbs, but in the process of being colonized by young hardwoods.   I had lots of seral  saplings like black cherry and persimmon scattered in little thickets and copses among the Andropogon-dominated  grassland.  Other ruderal taxa like Passiflora and Sida were abundant in spots.   It was a bird magnet.

The view from my backyard in November 2008.

The view from my backyard in November 2008.

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The view from my backyard in February 2009.

In my first winter here, I had grasshopper sparrows, a pair actually, a bird I had never associated with feeder visiting before; white-crowned sparrows, including a mature adult; vesper sparrows; song sparrows; and numerous indigo and painted buntings in or around my backyard gardens and feeders.

Then progress came.  That 50-odd acre tract is now occupied by Citrus Grove Elementary School (aptly named, at least), and the amount of bird-attracting habitat has plummeted from over 50 acres down to my ¼ acre lot and its densely planted gardens.   The diversity of birds passing through my yard, both as feeder visitors and transient migrants, has followed suit.

One of the first acceptable shots of the male I got. Rather have him off the feeder, but you take what you're given, G.

One of the first acceptable shots of the male I got. Rather have him off the feeder, but you take what you’re given, G.

So seeing a painted bunting these days, especially an adult male, is a miraculous gift to me.  But once I had that gift, greedy bastard that I am, I wanted more.  There’s a progression for the obsessed and deranged birder/photographer – see it well (always the best part), photograph it at even marginal quality if that’s all I can get, and finally, obtain high-quality images.   Success at the first two stages doesn’t guarantee the last will follow – my experience with the buntings is that they can appear and disappear at any time.

Even against a background with matching colors, this bird stands out.

Even against a background with matching colors, this bird stands out.

The paradox of painted buntings is that though not uncommon, they are so infrequently seen, particularly away from feeders.  I see them in the field perhaps 10 times a year, tops, including males and greenies.  But watching them around the feeders reveals why – when they’re not actually feeding, they spend their time in the densest, darkest cover they can find, usually in the very center of shrubberies.  They disappear.    When they do venture into the open, they are quite flighty.  They bolt quickly back to cover at the slightest movement or unexpected noise.

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So their behavior is clearly related to the incredible gaudiness of their plumage – they don’t want to expose themselves unnecessarily to sharp-eyed predators, such as sharpies and Cooper’s hawks.  Which raises a question – why don’t they molt out of this bright breeding plumage during the non-breeding season?

Other members of the genus Passerina, like the indigo bunting, do just that.  The brilliant blue males molt most of their bright blue feathers after breeding, acquiring a female-like dull basic plumage.  They then molt again prior to breeding in the following year, acquiring a new brilliant blue alternate plumage.

Male indigo bunting in alternate plumage. Photographed at Occoquan Bay NWR in Woodbridge, Va.

Male indigo bunting in alternate plumage. Photographed at Occoquan Bay NWR in Woodbridge, Va.

Female indigo bunting, photographed in Lake County.

Male indigo bunting in basic (non-breeding) plumage, photographed in Lake County, FL.

The extreme sexual dimorphism (or more accurately, dichromatism, or differences in coloration) between male and female buntings in the genus Passerina is suggestive of strong sexual selection by females during courtship and mate choice.  Females apparently prefer more brightly colored males, which leads to evolution of more colorful males and increasing divergence between male and female plumage.  Pigmentation in some male birds, especially the yellows, oranges and reds produced by the carotenoid pigments, is derived from feeding on plant materials; more brightly colored males may be more successful foragers.  That’s a quality a female bird looking for some good genes for her offspring can get behind.

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Dichromatism has costs for the males, though.  They are far more conspicuous, and so in many dichromatic species, the males revert to a dully-colored, cryptic basic plumage once the breeding season ends.  Male painted buntings don’t attain their brilliant definitive alternate plumage until they are nearly two years old, which also suggests there are negative consequences associated with the transition between a greenie and a spectacular adult.  So why don’t painted bunting males revert to a cryptic greenie plumage after breeding?

The male with his bitch Coco.

The male with his bitch Coco.

That’s a puzzle for brains bigger than mine.  My challenge right now is to watch these birds as much as possible when I get the chance.  If I’m lucky, that will be all winter long for this particular male, but I’m not optimistic about that.  He’s been around, visiting the feeders at least briefly every day, for 8 days.  And today he came back with his little friend, Coco.   She gonna’ be livin’ here  too.   (Big up to JJ for sharing the Coco clip with me).

Coco.

Coco.

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Bipolar robins

American robin, Tiger Bay State Forest.  The woodland phase.

American robin, Tiger Bay State Forest. The woodland phase.

December 14, 2013

I spent a half hour or so with a small flock of American robins deep in the mesic flatwoods of Bear Swamp Road, in Tiger Bay State Forest last week.  A little bit earlier in the morning I had seen another small flock in a cypress swamp in the nearby Woody Tract.   Aside from a couple of small flyover flocks, this was the first time I’d spent much time watching robins this fall.

If there’s one bird nearly every North American with a functioning brain can identify correctly, the American robin would have to be a good candidate for that honor.  Yet despite their abundance and extreme compatibility with some forms of human-modified landscapes, it’s surprising to me how little I really know about robins.  Especially during their winter residence in Florida.  They can be incredibly abundant and conspicuous at times, yet surprisingly shy and secluded at others.  The winter behavior of robins strikes me as bordering on schizophrenic.

The lawn robin.  Northern Virginia.

The lawn robin. Northern Virginia.

My first encounters with robins were probably like those of most people – as breeding birds in suburban habitats.  The sight of a robin running across a well-manicured lawn, stopping, cocking the head to one side as if listening, and then pulling out an earthworm like a strand of spaghetti is iconic for this species.   A pair sometimes nested in a thicket of vines just outside the back door of the house in Virginia where I grew up, and the constant coming and going of both parents bringing food to the insatiable young, then carrying away their feces in nice tidy little membrane-bound spheroids taught me how demanding the work of passerine parents taking care of  nestlings can be.  Spot-breasted fledglings follow their parents across the lawn begging for free food when they are fully capable of taking care of themselves.  Their departure in the fall, and more gratifying, their return in the spring, were highly anticipated events for me as I was just beginning to sync my life to that of the activity patterns of the birds that enthralled me.

Bringing food for the nestlings.  Scanned from a slide taken in Northern Virginia.

Bringing food for the nestlings. Scanned from a slide taken in Northern Virginia.

Poop removal detail.  She takes the fecal sac directly out of the little bird's bum.  Scanned from a slide taken in northern Virginia.

Poop removal detail. She takes the fecal sac directly out of the little bird’s bum. Scanned from a slide taken in northern Virginia.

Recently fledged American robin.  Scanned from a slide taken in northern Virginia.

Recently fledged American robin. Scanned from a slide taken in northern Virginia.

It wasn’t until I moved to Florida that I saw the other side of their lifestyle and life history.  The return of the robins is still a signature event in the phenology of Florida birds, but here it occurs in late fall and early winter, as huge flocks of robins move into the state to spend the winter.  It’s their winter behavior that intrigues me most now.   During their stay in Florida, between about October and April, they behave as if they were two different species.

A small winter flock of robins.

A small winter flock of robins.

Though Stevenson and Anderson point out in their essential book The Birdlife of Florida that migration of robins in Florida peaks in October, that seems early to me.  Most years I don’t first see robins until well into November.   In the 7 years I did weekly bird censuses at Emeralda Marsh Conservation Area in Lake County, the earliest I ever saw American robins was the 1st week of November, and I usually didn’t start seeing them in significant numbers until much later, well into December and January.

Seasonal abundance of robins at Emeralda Marsh Conservation Area.

Seasonal abundance of robins at Emeralda Marsh Conservation Area.

Part of the biphasic nature of wintering robins in Florida is their relative inconspicuousness during the first month or two they are here.  I usually see my first robins as small to medium flocks of anywhere from a few to a couple dozen birds, flying in a very determined fashion fairly high.  They are on their way to somewhere.  A few calls from the passing flock often first clue me in to their presence.   I’m especially likely to see these flocks early or late in the day, when the birds are dispersing from or returning to their nightly roosts.  Communal roosting is a big part of the lifestyle of robins, during both the breeding and non-breeding seasons.   Male robins during the breeding season leave their mates at the nest each night and congregate to roost with other hooked-up males.  I’d love to be a fly on the branch at one of those roosts to hear what these hen-pecked cocks have to say about their mates.   During the winter, mixed-sex roosts of American robins can number in the hundreds of thousands.

Feeding on black cherry, Prunus sp.

Feeding on black cherry, Prunus sp.

While in Florida, robins feed heavily on fruits; as much as 90% of their diet in winter can come from fruits of as many as 50 genera of plants.  Their frugivorous behavior may have a lot to do with their markedly variable behavior.

A woodland phase robin in the scrub of Ocala National Forest.

A woodland phase robin in the scrub of Ocala National Forest.

During November and much of December in most years, the occasional flyover flocks and the even less frequently seen feeding flocks are my typical experience of robins.  When I find feeding flocks, they are nearly always in fairly dense, closed-canopy hammock or swamp forest, where the birds are usually pretty quiet and quite easily spooked.  Sometimes they are down on the ground hunting for invertebrates, and sometimes up in the treetops, sometimes in the act  of digesting fruits.  Robins regurgitate the seeds of some of the larger-pitted fruits they eat, and there’s a very stereotyped sequence of behavior leading up to the egestion of a pit, culminating with a lot of convulsive gular movements and the jettisoning of the seed.    My impression of robins during this time of year is much more that of a more typical thrush such as a wood thrush or hermit thrush – fond of deep woods and a bit wary and mysterious.

Yakking up a fruit pit.  Renowned frugivorous bird expert Dr. Stewart Skeate was unable to ID the fruit from which this seed came.

Yakking up a fruit pit. Renowned frugivorous bird expert Dr. Stewart Skeate was unable to ID the fruit from which this seed came.

But not too much later, perhaps in late January or February, these big flocks of robins show a remarkable behavioral shift – they go urban.  They appear in large numbers in heavily anthropogenic habitats.  In DeLand, they show up on lawns, in gardens, and in fruiting trees that still retain some of their crop.  And they become dramatically more tolerant of human presence.  On Stetson’s campus and in nearby residential areas they first go after the big inflorescences of sabal palms and a variety of other fruiting trees and shrubs.  Horticultural hollies of various sorts are a favorite, as are the native hollies like dahoon (Ilex cassine) and gallberry (Ilex glabra), for the flocks that choose to remain in natural habitat.

Urban phase American robins and cedar waxwings feeding and drinking together on a Stetson lawn.

Urban phase American robins and cedar waxwings feeding and drinking together on a Stetson lawn.

Often accompanied by large numbers of cedar waxwings, these mass incursions into town and the coincident change in their behavior have to be one of the most spectacular natural history events to regularly occur in urban Florida environs.  Lawns can be covered with flocks of dozens of robins, running every which way while eating inverts and picking up dropped fruits.   Tree species with large fruit crops can be swarmed by flocks of hundreds of birds methodically harvesting a few trees at a time.  Like many flock-feeding frugivorous birds, these aggregations of robins can be swirling maelstroms of activity, with individual birds never staying in one spot for more than a minute or two before moving on to a new branch.    And unlike the standoffish woodland robins of November and December, these urban birds don’t seem to mind being around people that much.

Lawn-feeding robins in DeLand

Lawn-feeding robins in DeLand

Feeding on fallen Sabal palm fruit.

Feeding on fallen Sabal palm fruit.

Particularly during rain-free periods of a few days or more during Florida’s dry season, water can be a limiting commodity for these flocks of robins and waxwings.   On my morning drives to work through lovely old residential neighborhoods along W. Minnesota Ave., during the few weeks when these two species invade the town it’s not unusual for me to see small mixed flocks of robins  and waxwings at nearly every corner puddle that has accumulated from nearby lawn sprinkler systems.   The little dudes sometimes get quite feisty over access to a small pool of water.

Urban phase robin bathing

Urban phase robin bathing

Urban phase robin beefing with the waxwings

Urban phase robin beefing with the waxwings

It’s just a joyous time of year to be in and around DeLand.  Not only are the birds more obvious when in town, but they are also much more vocal and approachable.  Sometimes you see and hear robins and waxwings nearly all day long, everywhere you go in or around town.

In late afternoons during these months, I often see large loose flocks of robins flying to the northeast, presumably converging on some huge roosting aggregation, perhaps somewhere in the forests of Lake Woodruff NWR or Ocala National Forest.   At Emeralda, some mornings I saw continuous strings of robins flying in the same direction, presumably leaving a roost; these flocks sometimes numbered in the thousands.

Yakking a cherry pit

Yakking a cherry pit

And then as winter begins to wind down, almost overnight they seem to disappear.  The pullout of the big wintering flocks occurred in February to March when I was censusing birds at Emeralda.

So the obvious unanswered question for me about the wintering behavior of robins in Florida is this: why the dramatic change in habitat and behavior in mid-late winter?  Does the movement of robins into towns and suburban habitats at that time indicate that they have depleted most of the fruit crop in the woodland habitats, where it would seem that they would rather be?  Seems a bit too simple to me, and I love simple explanations.  And even if that is one of the driving factors, why the huge change in behavior, especially their tolerance of human proximity?

Urban robin looking for some grass among all the pennywort on this Stetson lawn.

Urban robin looking for some grass among all the pennywort on this Stetson lawn.

Even for incredibly common and easily observed birds like robins, it’s stunning how little we really understand about how they live their lives, and why.

I heard a small flock of robins flying over my house just bit earlier today, heading towards that big presumed roost to the north somewhere.  They’re still in the mysterious phase of their Florida sojourn.  What a treat it is to look forward to their upcoming schizoid break, knowing that within a month or two I’ll be able to immerse myself in the presence of the ubiquitous urban robins.

 

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The double whammy

December 5, 2013

Grading exams is like flossing – you have to do it, but it’s rarely enjoyable, and sometimes it’s downright bloody and painful.  When confronted with this miserable job, I seek any relief from the tedium I can find.  So this afternoon with a passel of essay questions to score by tomorrow, I took my tests home to grade at a snail’s pace on my back patio, where I could keep an eye on the bird feeders and gardens.  I’ll take any distraction at all as an excuse to postpone grading for a minute or two.

Common ground dove

Common ground dove

And I saw this bird.  When I first saw this young common ground dove working through the millet seeds in the platform feeder, it’s head and neck moving like the needle on a sewing machine, it seemed totally normal.  When I saw it in greater detail through a telephoto lens, it was clearly not.  It appeared to me at first to be carrying an uncracked sunflower seed in its beak while simultaneously picking at the millet.  Closer inspection revealed that it was abnormal in two ways – both the upper and lower beaks were unusually curved, and perhaps a bit elongated, and the distal portion of both maxilla and mandible each hosted a big nasty wad of smegmaceous-looking material.  Even viewing it through 10x binoculars I couldn’t quite figure out what it was – fungal growth, keratin overgrowth of the beak, a tumor … maybe a bit of each.  But it didn’t seem to have impacted this dove much – it looked to be in decent shape, and its plumage looked reasonably well-preened.

That's some nasty looking stuff growing in there.

That’s some nasty looking stuff growing in there.

Turn to the right.  Turn to the right.

Turn to the right. Turn to the right.

It’s quite amazing how birds afflicted with these seemingly severe maladies can continue to function normally.  A bird’s beak is obviously its main feeding implement, but it does so much more.  Birds use their beaks for many of the same functions that mammals perform with their hands.   Grooming and preening, manipulation of objects in their environment, exploratory behaviors, and so on.  A malfunctioning beak system would seem to present insurmountable hurdles to the continued well-being of a bird, but it often isn’t so.

The DeBary thrasher, Hemignathus debaryi

The DeBary thrasher, Hemignathus debaryi

I’ve seen a number of these differently-abled birds visiting my feeders over the years.  There was a brown thrasher that visited for several months when I lived in DeBary who had a bill that reminded me of the bizarre Hawaiian honeycreeper, the akiapolaau (Hemignathus munroi).  Though its beak looks like something designed by a crack team of FSU engineers, it is actually functional in the highly specialized feeding niche of this honeycreeper, which uses the stouter lower mandible to hammer at bark, and the long decurved maxilla to probe cavities.  But for the thrasher it had to function like a normal thrasher beak.  Imagine trying to pick a splinter out of your finger with a pair of tweezers whose points miss each other by a centimeter or two.  But like the doubly-cursed ground dove, the thrasher seemed to be making it work.

The southern blue crossbill

The southern blue crossbill

Last winter a severely deformed blue jay visited my yard and feeders for several months.   Dubbed the blue crossbill, she was able to pick up seeds with no apparent difficulty, but I never saw her holding one between her feet and hammering it with that asymmetrical monstrosity.   I saw this bird being courted by another blue jay during the spring, and I was hopeful that she would return to the feeders with her offspring a bit later in the year.   I haven’t seen her again since spring, though.

Pick up seeds?  NFP

Pick up seeds? NFP

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Probably my favorite beak-deformed friend is an American crow who I call L.B.  L.B. was one of the first crows to begin visiting my yard and feeders 5 years ago when I moved to a new house in DeLand.  Along with his mate, he has hung around my neighborhood ever since, though sometimes months pass between sightings.  L.B. stands for Long Beak (I’m one imaginative fucker, no doubt), and he is the only crow I’m able to recognize as an individual among my neighborhood clan.  Every year since L.B. and Notch began visiting my yard they have brought their newly fledged offspring by as part of their extensive education.  Although I’m sometimes able to recognize an individual bird for a period of months due to some feather abnormality or molt, L.B. is the only one of my crow buddies that I always know.  Which is kind of cool.  In my demented mind I feel like I have a long-term relationship with these amazing corvids who grace my yard with their presence (The Gifts of the Crow, as John Marzluff phrased it so eloquently).   But L.B.’s deformity is remarkably minor, and clearly doesn’t impact his survival or fitness in the least.  He’s one fecund dude.

L.B., my corvid friend.  Or whatever.

L.B., my corvid friend. Or whatever.

L.B. is easily recognizable, unlike my other home corvids.

L.B. is easily recognizable, unlike my other home corvids.

L.B. and his better half.

L.B. and his better half.

Beak deformities are a phenomenon of great interest to ornithologists these days, for two reasons.  They are increasing dramatically in some areas, and we really don’t have any unambiguous answers, or even attractive hypotheses, as to what is causing them.  The U.S. Geological Survey’s Alaska Science Center has been one of the most active participants in the quest to document and understand this disturbing phenomenon, but they have no clear answers as to the etiology.  What they have shown convincingly is how widespread these deformities are – they are found in around 16% of all Northwestern crows and 7% of the black-capped chickadees in Alaska.   A variety of causative agents have been suggested, including pesticides and other chemical contaminants in the environment, nutritional deficiencies, disease, parasites, and genetic changes.  None of them is clearly supported by the data collected by the USGS researchers, though.

Are deformed bird beaks telling us something about pernicious changes in the environment, like the proverbial canary in the coal mine?  I hope not, but fear so.