A marauding band of blue jays came screaming through the woods behind our house yesterday. The pleasant invasion made me realize that we haven’t talked about our winter birds recently. So, let’s briefly focus on blue jays (Cyanocitta cristata), which always seem to have a mischievous gleam in their eyes:
As do crows and some other birds, blue jays spend the winter in larger groups than at other times. It’s thought that this winter flocking is a defensive measure (more eyes, ears, and squawks) to detect and deter hawks and owls. Those bird-eating raptors can see and attack their prey better in a leafless world – especially if that prey is bright blue.
On that subject, the jays are not partly blue in the sense that their feathers contain blue pigment; they’re partly blue because the structure of those colorful feathers refracts light in a way that our eyes perceive the color blue. If you ground those blue feathers, we’re told, you’d get a pile of brown beta-keratin, the protein that birds share with reptiles due to their common origins. (Images taken in Brooklin, Maine, in prior years.)