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Wing Molt in Raptors

posted by Jerry Liguori at
on Thursday, July 25, 2013 

I have a few e-mails in my inbox about wing molt in raptors that I haven't responded to yet, and I love the subject…so why not respond on the blog.

I just want to clarify one thing about wing molt. It has always been the accepted thinking that most raptors replace their primaries in order from P1 - 10 during their first molt. Is this true? Well, yes and no….P1 (the innermost primary) might be replaced first, but often birds replace P2 or P3 first…or sometimes all 3 simultaneously. When simultaneously, you see birds in spring that have large gaps in the wing and wonder how they can fly so well. So, just to clear that up, P1 is often not the first primary to drop in molting raptors. Take a look at these great examples of juvenile Red-tailed Hawks photographed by Todd Steckel molting into their first adult plumage. P1 is still juvenile…("click" on images to enlarge)

Hawk banding is a great way to learn about molt, and banding hawks in spring is different than banding in fall. In fall, birds molting are completing their molt and the last few retained feathers have not come in yet. In spring, birds are beginning a molt, and the first feathers to come in either are, or have come in. So you get to see different stages of molt between the two seasons. With the popularity of digital photography, there are thousands of images to search with the "click" of a mouse, which makes researching molt and plumages much easier!

For more of Todd's excellent photography check out: http://www.flickr.com/photos/rtsteck/


16 Comments:
Anonymous Anonymous said...

Thanks, Jerry! Debunking these old myths that were taken for fact, is a great service to the birding community.

Pete Gustas

July 26, 2013 at 8:41 AM  
Blogger Jerry Liguori said...

Glad you like my posts Pete!

Half-truth anyway

July 26, 2013 at 8:50 AM  
Blogger Mia McPherson said...

I've been seeing quite a few raptors in various stages of molt this past week. Always interested in the things you share Jerry!

July 26, 2013 at 2:28 PM  
Blogger Jerry Liguori said...

Can't wait to see your pics....maybe I could post one?

Thanks Mia, I'm always interested in what you have to share as well!

July 26, 2013 at 2:31 PM  
Anonymous Anonymous said...

Thank you for this Jerry, I love reading about stuff I didn't know before.

July 28, 2013 at 3:48 PM  
Blogger Jerry Liguori said...

You are welcome, I hope I have more in the future that you enjoy

July 28, 2013 at 7:49 PM  
Blogger Wally Jones said...

This is quite interesting and explains a lot of what I've been seeing in the field. ("How can that hawk even stay in the air with so many feathers missing??")

Thanks to Mia McPherson for directing me to your wonderful site! I have a lot of reviewing to do of your past articles!

-- Wally in humid central Florida.

July 29, 2013 at 8:39 AM  
Blogger Jerry Liguori said...

Hi Wally

Glad you found my website, hope you like what you see!!!!

July 29, 2013 at 2:41 PM  
Anonymous Ron Dudley said...

Another intriguing raptor lesson. The red-tails up in the Centennial Valley of Montana were an extremely ragged bunch last week. Got to admit that every time I was looking at one through my viewfinder I wondered "What would Jerry say about this bird?...

July 29, 2013 at 5:42 PM  
Blogger Jerry Liguori said...

Hah, I often ask....."what would Ron do?" In certain situations when dealing with people.

July 29, 2013 at 6:42 PM  
Anonymous Derek Lyon said...

This really helps! For years I've been looking at photos of raptors, and being into molt, trying to identify each feather. I would usually figure out which was P1 and then start count out to P10, but sometimes I wouldn't get to 10 before running out of feathers. If the first feather molted might not be P1 then I'm not loosing my mind. Thanks Jerry.

August 2, 2013 at 8:43 AM  
Blogger Jerry Liguori said...

Hah, you are not losing your mind Derek.

Glad you like the posts, I love molt as well.

August 2, 2013 at 11:06 AM  
Anonymous Anonymous said...

P1 & P2 are still juvenile feathers, correct? Otherwise I'm only counting 9 and I'm missing something. I'm just starting to get serious with raptor watching and I find this blog a great help and supplement to your books.

September 9, 2013 at 12:45 PM  
Blogger Jerry Liguori said...

Hello Anonymous

Yes, you got the point of the post, sometimes its hard to see which feather is missing. Where do you watch? I'm glad you like the blog and if there's a topic you prefer, I could try to blog about it.

September 9, 2013 at 1:15 PM  
Anonymous Derek Lyon said...

After your help, I could make sense now of this 1992 article in the Journal of Raptor Research, it's called: Molt of Flight Feathers in Ferruginous and Swainson's Hawks by Josef K. Schmutz. It mentions what primaries molt first and lots of them don't molt P1 first. I'm looking for more articles like this now and I'll post them here if I come across any more.

January 10, 2014 at 1:17 PM  
Blogger Jerry Liguori said...

Sounds great Derek -- It was and still is assumed by some (based on old assumptions) that P1 comes out first in certain families, but that's not necessarily the case, it is often not the first primary to drop in its first molt or successive molts.

January 10, 2014 at 1:22 PM  

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