December 3, 2010

hairy woodpecker – a lesson in comparative size

Bird identification is not a simple decoding of a painting by numbers. It requires an entire toolbox of tricks. Childhood learning tells of one bird, two bird, red bird, blue bird however, the adult world muddies life with variables like molting, age, air temperature and location all which effect the physical coloration of a bird. Tools such as sound, location, shape, and even attitude help in identification. The Hairy woodpecker is a good example of an identification problem that cannot be solved by coloration. Compare the hairy to the downy woodpecker in a field guide and find a slightly pumped up, bad joke version of the downy.  In highway commuter terms the hairy is the Highlander to the downy’s Rav4

Imperceptible differences in plumage leave size as the best clue to identification. If the two woodpeckers aren’t perched next to each other on the branch (wishful thinking) look at the size of the bill in comparison to the overall size of the head. The downy’s bill is tiny, representing about ½ the length of its own head while the hairy’s more substantial bill is equal to the total length of its head. With both species of woodpecker active all winter long this is a good time of year to get a grip on this backyard identification challenge.  

No comments:

Schedule Alex for a field trip, lecture or classroom visit

Enter your email address to receive notifcations when new posts are published:

Delivered by FeedBurner