Molecular Natural History is a series of posts highlighting what population genetic data reveals about some of my favorite organisms. There’s no rhyme or reason to what species I’ll feature for this, beyond the fact that they’ve made me stop and look closer when I see them along a trail or in my neighborhood. If you’d like to write about the molecular natural history of a favorite taxon, why not pitch a guest post?
Step into the woods almost anywhere in North America and odds are good you’ll be met by a welcoming committee of tiny birds darting among the lower branches of the trees, shouting their name at you, chick-a-dee-dee-dee. Chickadees are delightful and accessible birds: proportioned like live, flying Peeps; curious and bold enough to risk visibility when you venture into their territory; happy to put on a show in your backyard for the low low price of unlimited sunflower seeds.
In many parts of the continent, they’re also an introduction to the challenges of bird identification. Starting with my mother’s old Peterson field guide, I followed the novice birder’s classic emotional arc from excitement at being able to name the songbirds and raptors and corvids that flew through our backyard — to the realization that some of those names were much trickier to apply than others. The first of these challenges I remember cracking was the distinction between the black-capped chickadee, Poecile atricapillus, and the Carolina chickadee, P. carolinensis, whose ranges abut in south-central Pennsylvania. Their size, shape, and shading of wings and underparts seemed relatively distinguishable, as did their songs —until I learned that they hybridize.
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