To identify the species, sex, and age of a bird, a bird bander in North America relies either on personal experience with the species or on the massive handbook of bird descriptions known as the Pyle Guide. The Pyle Guide is full of confidence-instilling descriptions like “Juvenile rectrices usually pointed, but occasionally truncate” and “Male scapulars brownish-black, compared to blackish-brown in female.” To make matters still more confusing, birds can vary from site to site, meaning that the description in Pyle based on a population 100 miles distant may not be correct for your own local population. One of the best tools a bird bander can have, as they squint at a bird and wonder whether its iris is “red-brown” or “maroon” and whether that is even relevant to their local birds, is a comparison photo showing local birds.
You have to be a bit lucky to capture such photos: you have to happen to catch both birds at the same time. When you usually catch five or fewer birds at a time, as we do, the chances that any two of them will be an informative comparison becomes small. Each of these pair photos is a little special for this reason.
While the thunderstorms and fog kept every other bird subdued, one species sang out boldly through the Smoky Mountain forests: my friend the junco. In North Carolina these juncos were not the birds I did my PhD work on, however; those were in the Oregon Junco group, with chestnut backs and sides and dark hoods, while these were in the Slate-colored Junco group, as all-over grey as their name implies. I was extremely excited when one of these new juncos decided to fly into our net so that I could take a closer look and hold a new subspecies of junco.
We head for the Smoky Mountains full of confidence: the Kentucky Warblers may have proved to be elusive, but every source suggests that our new quarry will be more forthcoming. The Canada Warbler is known to be a particularly aggressive bird, likely to respond quickly to our calls; the American Redstart is a common and easy-to-find species. We will catch them easily while enduring less moisture and fewer mosquitos than before.
We have ten days in North Carolina to get DNA samples from three species breeding there. Our target for the first five days is the Kentucky Warbler, a golden bird with a black mask whose population is declining. It is a highly local bird, meaning that we can’t just find them anywhere within the shaded region of a large-scale range map: we need specific location information. We get this information from eBird, following birders’ reported sightings to a place about an hour south of Raleigh called Howell Woods.
“How did y’all find us?” asks the manager of Howell Woods. “There’s folks on our road that don’t know we exist, but somehow we get birders from Europe asking about Kentucky Warbler and Mississippi Kite. I never understand it.”
I got my start in ornithology studying the love lives of House Wrens. House Wrens pair up to raise their babies in a manner compellingly analogous to the human “nuclear family;” but, like most birds, both partners also often “cheat” on each other (i.e., copulate with other birds). This means that the male wren may have chicks in other nests besides his own, and he may end up caring for chicks that are not biologically related to him. (Note: edited. The original version of this sentence had a mistake.)
This sets up a number of interesting questions, such as: why cheat on your partner? Are the chicks sired by outside birds somehow better? Do males know when they are caring for chicks who aren’t their own? The answer to the latter question seems pretty clear (no, the males do not know), but the former two are more challenging.
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.
This nest is a great example of juncos’ love of sloping ground. In some cases, like this one, the sloping ground is slope-y enough to call a wall. I wouldn’t call this a typical junco nest, but it’s not really surprising either: juncos are reliably creative with their nesting choices, which must make it difficult for predators to find them. This nest certainly seemed well-hidden—and it didn’t have to worry about being stepped on, either.
I’ve seen a lot of junco nests in my four years of field work. Rarely, I’ve been lucky enough to happen upon the nest of something other than a junco. I don’t find enough of these other nests to study them, so they don’t help me in my research—but boy, is it fun to find them!
Quick review: this is a junco nest.
This is not a junco nest:
Some major differences: the junco’s is a ground nest, while this one is a cup nest, suspended above the ground in the branches of a bush. The chicks are covered in light greyish fuzz instead of the junco chicks’ dark fuzz, and are maybe a bit stockier than the junco chicks.
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.”