Dec 18 2009

Anatomy: Patagium, Patagial

Published by at 7:02 am under Bird Anatomy

Patagial mark on Red-tailed hawk (phto by Chuck Tague)I came across the term "patagial mark" at the Allegheny Front Hawk Watch in November when I was having trouble identifying a passing red-tailed hawk.

Usually red-tails are easy for me to pick out by their size, shape and belly bands but the bird in question had a pale belly like the one pictured here, was far away and was fighting the wind.  A fellow birder pointed out that I could always identify a red-tailed hawk if I looked for the "dark patagial marks."


The patagium is the stretch of skin on the leading edge of the bird's wing extending from the head to the wrist.  The noun patagium is rarely used but its adjective form, patagial, is fairly common.

For instance, red-tailed hawks have light-colored underwings and a dark patagial mark, shown here circled in pink.  It's a good field mark because no other hawks in eastern North American have this combination.  Try comparing the underwings of red-tailed hawks to red-shouldered, broad-winged or (western) ferruginous hawks for a bit of fun.

Another use of the word is in "patagial tags" which are bird bands applied to the wing on large soaring birds so that researchers can read the tag while the bird is in flight.  The tag hangs below the wing so it doesn't interfere with the bird's ability to fly.  California condors, our biggest bird, have the biggest patagial tags.  Click here to see a patagial-tagged ring-billed gull Chuck Tague saw in Florida last winter.

So, yes, I knew about those dark spots on the red-tail's wings.  I just didn't know they were so unique.

(photo by Chuck Tague, altered to highlight the bird's patagial mark)

8 responses so far

8 Responses to “Anatomy: Patagium, Patagial”

  1. Dianeon 18 Dec 2009 at 9:14 pm

    I think that tag would be annoying to a bird. A parrot would remove it in less than ten minutes!

  2. nancy lomsdalenon 08 Jan 2014 at 10:25 pm

    I keep seeing a hawk and I swore it had a blue stripe on its wing. Also the tail is bright red.

  3. Kate St. Johnon 09 Jan 2014 at 5:46 am

    Nancy, where have you found this hawk? (the city/state location of the hawk helps identify it) Also is the stripe in the patagial area or somewhere else? Is the tail red on the top? underside?

  4. nancy lomsdalenon 09 Jan 2014 at 10:42 pm

    It may be a tag but I saw it again today. The red is underneath.It’s located in Mt.Vernon,Wa.

  5. Kate St. Johnon 10 Jan 2014 at 9:58 am

    Hmmm. Might be a tag, especially if the whole tail isn’t red. Otherwise, if it’s a small raptor it might be an American kestrel. Their undertail is rusty red.

  6. nancy lomsdalenon 10 Jan 2014 at 3:31 pm

    Thanks, hopefully I’ll get a picture one day.

  7. Kendallon 23 Feb 2014 at 1:41 am

    I believe the bird in question is a red-tailed hawk that was relocated from SeaTac airport. I live in Mount Vernon and have seen one like it on Memorial Hwy. on several occasions.

  8. Kc Waddellon 27 Jul 2017 at 10:09 am

    Thank you!!!!!!!!!!!!!! A visual is so helpful. I was trying to figure out what part of the hawk was actually the patagial and your picture really helped! Now I have to check out your blog!

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