Readers’ wildlife photos

December 11, 2022 • 8:15 am

It’s Sunday, and we have the 151st consecutive Sunday installment of bird photos from John Avise. John’s captions and IDs are indented, and click the photos to enlarge them.

Downies and Hairies

Downy Woodpeckers (Dryobates pubescens) and Hairy Woodpeckers (Leuconotopicus villosus) are two of North Americas most widely distributed species, both found almost continent-wide.  They are nearly identical in plumage, but differ in body size and bill length.  Their close similarity in plumage formerly was thought to indicate a very close evolutionary relationship, but a surprising molecular–genetic finding in 2015 challenged that notion.  The molecular data documented that these two look-alike species are not one another’s closest relatives, but instead are divergent enough to warrant their placement in separate genera.  This in turn implies that the close plumage similarity between these two species is due to convergent evolution.  But what selective pressures could explain such remarkable plumage convergence?  Nobody seems to know.  Although some hypotheses have been advanced, they seem far-fetched to me.  For example, one hypothesis posits that Downies evolved to mimic Hairies because the latter species is aggressive and often wins when competing for food with other kinds of birds.

In any event, this quandary is on my long bucket list of puzzling avian questions I would love to have answered.  This week’s post offers several photos of Downies and Hairies (and a couple of their closer cousins), the intent being to show how similar in appearance these two distantly related woodpeckers are.  [In each species, males can be distinguished from females by a red patch on the back of the head.]

JAC: Here’s the reference John gave me for the revised phylogeny: Fuchs, J.; Pons, J.M. (2015). A new classification of the pied woodpeckers assemblage (Dendropicini, Picidae) based on a comprehensive multi-locus phylogeny. Molecular Phylogenetics and Evolution. 88: 28–37.

Downy male:

Another Downy male:

Hairy male:

Another Hairy male:

Downy female:

Another Downy female:

Yet another Downy female:

Hairy female:

Another Hairy female:

White-headed Woodpecker, Leuconotopicus albolarvatus (a closer genetic relative of the Hairy):

Nuttall’s Woodpecker, Dryobates nuttalli (a closer genetic relative of the Downy):

6 thoughts on “Readers’ wildlife photos

    1. Body size is the key– the Hairy is about 50% bigger than the Downy (but this can be very hard to gauge unless the two species are seen together). Another good clue is bill length– the Downy’s bill is small (only about 1/3 of its head length, whereas the Hairy’s bill is bigger and more spikelike.. There are also some minor differences in plumage, which you can readily find on the Internet or in field guides. But telling them apart can often remain difficult.

  1. Could I point out the Eurasian species also from a different genus, Dendrocopos major, the Greater spotted woodpecker, a Palearctic species,
    https://en.m.wikipedia.org/wiki/Great_spotted_woodpecker
    And the sister species of pubescens, Dryobates minor, https://en.m.wikipedia.org/wiki/Lesser_spotted_woodpecker
    are also similarly marked, so could it not be an ancestral trait? Oh yes, black & red is also the colour of the pileated, & the Eurasian green woodpecker also has red & black on the face head area so is a better question why they have a red streak?

    Thanks for sharing John!

    1. Thanks for pointing out that a quite analogous quandary involves the look-alike Greater and Lesser Spotted Woodpeckers of Eurasia. Another puzzle for my bucket list!

  2. I can’t just read about taxonomy, I need a visual, either a phylogenetic tree or a cladogram or something like that. I get tripped up with who is nested within what and where and when they diverged. Still what my little walnut-sized brain can grasp is not what I expected. Convergence confounds us again! I do love these two little locals, but I usually need to see them near one another to tell which is the hairy woodpecker. since they don’t seem to be as common, I often confuzzle the two. I’ve never seen either of their “cousins”, but I get all the Missouri woodpecker species in my yard from time to time but I still haven’t made myself a natural log feeder I saw someone on here had made to attract the elusive Pileated woodpecker.

    Great photos and wonderful science, as always. Thank you.

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