Day 17: White-throated Sparrow

White-throated Sparrows are a common winter inhabitant here in Maryland. They are found at some season throughout much of North America, principally east of the Rocky Mountains.

The song of the White-throated Sparrow is one of the first bird calls I learned to recognize (after some coaching from Jared). It is a long, slow, and distinct series of whistled notes that many birders paraphrase as "Oh sweet Canada, Canada, Canada."

 

Evidently, White-throated Sparrows exhibit plumage polymorphism (there are white-striped and tan-striped morphs). I didn't actually realize that until doing some research just now! I have only paid attention to the white-striped morphs, so now I'll have to keep a look out for the tan-striped as well. On the white-striped birds, the crown is black with a white central stripe. On the tan form, the crown is dark brown with a tan central stripe.

 

Nerdy fun fact: While I was reading about the sparrow, I came across some fascinating information about the genetic and behavioral differences of the two morphs. The two polymorphisms are found in both sexes, occur in approximately equal numbers, and are due to chromosomal differences. Plumage differences are paralleled by differences in behavior and breeding strategy. White-throated Sparrows almost always pair with the opposite color morph for breeding. White-striped (WS) males sing more and are more aggressive than tan-striped (TS) males. TS birds of both sexes provide more parental care than WS birds. These attributes have made the White-throated Sparrow popular subject for studies of genetic, neural, and endocrine control of life-history characteristics.