Monday, December 31, 2018

HaIry Woodpecker vs Downy Woodpecker


Hairy Woodpeckers are outnumbered by Downy Woodpeckers at our feeder. The two species are quite similar. Note the longer, thicker bill and the white tail feathers of the first image of a male Hairy. If you look carefully, you can see the the female Downy Woodpecker’s outermost tail feathers have black spots. 

Most birders were surprised when ornithologists concluded, using morphological, behavioral, and genetic evidence, that the two woodpeckers are not each other’s closest relatives. The Hairy is closer to Arizona and Strickland woodpeckers of Arizona and western Mexico. The Downy’s are most similar to Ladder-backed and Nuttall’s woodpeckers of California and northern Baja California (Jackson et al. 2018; Jackson and Ouellet 2018). Why have the two woodpeckers evolved such similar plumage? I suspect one factor n=may be that a black and white plumage with a white stripe down the back must be ideal for survival in snowy northern forests.

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