Thursday, February 4, 2016

Hairy and Downy Woodpeckers

Distinguishing Hairy from Downy

Hairy Woodpecker (Male)
It is sometimes difficult to tell a Hairy Woodpecker from a Downy Woodpecker.  After all, they really do look a lot alike.  These are our most common woodpecker species, the Downy being more numerous than the Hairy.  They are generally non-migratory so they are with us year round.  They are loyal feeder birds where they enjoy suet, peanut butter and seeds.

Downy Woodpecker (Female)
The Downy and Hairy Woodpeckers are birds of both coniferous and deciduous forests.  They feed on insects, caterpillars and pupae, spiders, nuts and fruit.  They play a significant role in keeping our forests healthy.  They nest in holes in trees.

The male of both species can be distinguished from the female by the red nuchal patch.  That is the small red patch at the top back part of the head.  This is lacking in the female.

Hairy Woodpecker (Female)
The Downy and Hairy Woodpeckers can be told from other woodpecker species by the white patch on the back and the white flanks.  After that it gets more difficult.  The Hairy is larger; 24 cm compared to 17 cm for the Downy.  The bill length is useful to distinguish the two species.  In the Downy, the bill length is much less than half the width of the head.  In the Hairy, the bill length is more than half the width of the head.  The Downy also has dark bars on the white outer tail feathers which the Hairy does not have.  These are not always easily seen but are evident in the female Downy above.

Downy Woodpecker (Male)
That more-or-less makes it reasonably easy to tell them apart.  The only other problem is that bills are longer in males than in females.  So, that makes the male Downy approach the female Hairy in bill length.  The bill of the male Downy is still shorter than half the width of the head, however.  Note in the photo above of the male Downy the bill is longer than in the female Downy but is still shorter than half the width of the head.  The barring on the white outer tail feathers is not visible in this photo.

Isn't birding fun?  It certainly has its challenges.  Now, we have one more difficult question.  I have wondered this for a long time.  Why do we have two species which are so similar?  If you think about it, we have similar situations in other animal species; for example, red fox and gray fox, brook trout and lake trout.  But these woodpeckers are so similar!  And they are distinct species.  They do not hybridize (interbreed).  The only answer I can find to this question is that that have evolved in the same niche.  They probably came from the same ancestor and split off a long time ago and then evolved in the same habitat and geographical location.  It is strange and amazing how nature works.

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