Anatomy: Musing On Rear Toes

Close-ups on the toes of a Golden crowned sparrow, Sanderling and Snow bunting (photos by WIlliam Parker)
Close-ups on the toes of a Golden crowned sparrow, Sanderling and Snow bunting (photos by WIlliam Parker)

7 January 2011:

One of the fascinating things about birds is that each species is specialized and it's expressed in so many ways, even in their feet.

A couple of days ago fellow birder Bill Parker sent a me a message in which he mused on the length of birds' rear toes with photos to illustrate.  He said, "I was noticing in one photo that the Snow Bunting has really long rear toes."

As you see in Bill's pictures the rear toe, or hallux, on the golden-crowned sparrow (left) is normal for a perching bird, it appears to be missing on the sanderling (middle), and it's very long on the snow bunting (right).  I've blogged about the position of the toes but I'd never thought about their length so I did some research.

It turns out that rear toes are highly variable.  Many wading and water birds have a vestigial hallux that's so high on the metatarsus and so short that it doesn't touch the ground.  That's what happened to the sanderling.

But there are exceptions.  On cormorants the rear toes face (vaguely) forward and are webbed with the other three.  On kittiwakes the fourth toe is gone.

Birds' toes indicate their lifestyle.  Sparrows perch a lot so they need a grasping hallux.  Sanderlings walk on the beach (a lot!) so they don't need rear toes.  And snow buntings are perching birds who wear snowshoes.

Even we could use a hallux sometimes. "When I've been on a ladder painting, I've wished for a rear toe like the Snow Bunting," said Bill.

Check out the jacana's toes.  They'll certainly keep you on a ladder!

(photos by William Parker)

5 thoughts on “Anatomy: Musing On Rear Toes

  1. those jacana toes look like spiders. wonder if any animals ever try to eat them. i noticed this season that horned larks have long back toes. they also leave distinctly “sharp” or clearly delineated tracks on sand. when i see these tracks, i stop and look for the birds. someone else has made the same observation. found this photo online:

    http://www.flickr.com/photos/23660854@N07/5219716531/

  2. Funny you should mention this. I was reading the Nov/Dec Bird Watcher’s Digest the other day (I am farther behind with my magazine reading than my blogs) and Alvaro Jaramillo wrote an article titled “Open Country Winter Birds.” He mentions the Arctic bird Lapland longspur, so named, of course, for its long back toe. Like you, it’s not something I had thought about before!

  3. Yes, indeed, those are rear toes. Interesting that the Savannah Sparrow can turn its head so far back. I never noticed that before.

  4. it’s pretty amazing and a bit exorcist-like! are you looking at me?
    “take heed and do not underestimate the savannah,” it seems to say.

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