Readers who have been with me a while will remember “Buddy,” the white-spotted male junco who lived near my workplace for years. Unusually-colored juncos aren’t as rare as, say, the recently-spotted yellow cardinal, but they aren’t common either. (In my field work in the Sierras we banded ~500 juncos, and only one had a color abnormality.) As a lover of both rare birds and juncos, I get pretty excited about them when I find them.
This particular junco flashed up out of a bush as I was walking past. The size, tail, and movement pattern all said “junco”—but when the bird landed in a tree and I got a good look, my brain’s bird-ID function got confused: “Big chickadee!” it suggested. “Small kestrel! Big-small-chickadee-kestrel-junco!”
Every scientist has a few favorite science stories: those papers or sets of papers that we read early in our careers and then reread often, that we think of when we imagine our own ideal research program. One of mine—not exactly a hidden gem, as it’s in all the textbooks now, and is the subject of a very good general-audience book, The Beak of the Finch—is the Grants’ work on Galápagos finches. Peter and Rosemary Grant have spent decades documenting how bill size and shape in these finches fluctuates as rainy years and droughts change the food available on their small island. It’s as complete a picture of evolution in real time as anyone has ever drawn, and a powerful argument for predictable rules (like “bills must be the right size to open the seeds that are available”) leading to unpredictable outcomes in the complexity of a natural system. It’s beautiful.
I wanted to see if I could see similar patterns in the juncos. Like the finches, juncos are primarily seed-eaters. Unlike the finches, the juncos are not neatly contained on a small island; and unlike the Grants, I did not have 30 years to study them. Fortunately, I work in a museum, which is basically a biological time machine. Want to know what junco bills looked like in 1915? No problem!
Thus my time communing with the long-dead feathered denizens of the specimen drawers. Where the Grants had had to live through the decades of data they acquired, I took a shortcut.
Like all shortcuts, however, there were some downsides. I did not get to live in the Galápagos. Also, I was very limited in which juncos I could measure: I might be interested in juncos from a certain mountain range, but if a junco from that range hadn’t been stuffed and placed in a drawer 70 years ago, I was out of luck.
For birds, cleanliness is not optional. They rely on their feathers for flight and insulation, and only replace those feathers once or twice each year. In between molts, they need to keep their feathers as whole as possible.
Feathers, like our hair, are made of protein; and like all organic things, they degrade over time. Sunlight hastens this degradation, but certain aspects of the feathers themselves can slow it: dark feathers colored with melanin last longer in sunlight, for example. Of more concern, though, are the many creepy-crawly things that like to eat protein, and will happily hang out in a bird’s feathers, munching and laying eggs.
To combat these parasites, birds coat their feathers in protective oil from the preen gland located at the base of their tail, and they bathe.
But they have to be careful. Small wild birds are lunch for everything from feral cats to Cooper’s Hawks, and no bird wants one of these sneaking up on it while it is obliviously scrubbing behind its ears. So they bathe in bursts, a plunge into the water followed by a quick look around.
Did anybody see that?
This Chestnut-backed Chickadee is molting his head feathers, hence the odd colors.
After breeding, if you’re a bird, comes molting. Time to discard those old, worn, raggedy flight feathers and start with some fresh ones for the long haul of the fall molt, or replace sparse downy feathers with good warm ones for the cold of winter. This means that around now—from mid-July to September—you may see a lot of birds who aren’t looking their best.
Something is not quite right here. What is it?
I was supposed to be done with field work after summer 2015, but you know how it is. The birds call. You realize that a few more blood samples would put the patterns you’re seeing in context in an illuminating way. You miss those feathery little dudes.
The small amount of field work I did this year took place much earlier than my usual field work because I was sampling juncos at a much lower elevation. Down here, the juncos are breeding in mid-March. Up at my usual sites, they wait until late May. That early start happened to be convenient for me, since I needed to analyze any data I got in time to file my dissertation in mid-May.
We were searching for junco nests when I heard the unmistakable tic-tic-tic of junco alarm chipping. We followed the sound a ways and found a pair of juncos perched on a low branch, alarm chipping for all they were worth. Strange of the juncos to be alarm chipping at us when we were so far away, before, I thought. I wouldn’t have thought they’d see us as a threat from that far away. Odd birds. Directly below the branch with the agitated juncos was a small shrub. “The nest will be in there,” I predicted, showing off for my new field assistants.
I parted the prickly branches, and tiny pink beaks gaped hungrily at me. “There they are,” I said, pleased with myself. “Three chicks.”
And just as I said that, I saw the snake.