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Tails of Golden Eagles

posted by Jerry Liguori at
on Wednesday, September 18, 2013 

Ageing Golden Eagles to a specific year can be tricky because the amount of white in the wings varies in extent until adulthood when the white is absent, and wing molt can be difficult to assess without lots of practice. So, the best thing to key in on is the tail pattern and molt. Using the tail to age Golden Eagles is often much easier and more accurate than using overall plumage and wing molt. Of course be careful of birds with adult tails that have one or two secondaries with white at the base. In these instances, the tail has just been fully replaced of the last few sub-adult feathers, but the wings are one or two feathers behind. This occurs typically in birds that still have extensive white in the sub-adult remiges (secondaries and primaries), and take a bit longer to appear all-dark in the wings than some other Golden Eagles.

One more thing -- SY (2nd-year, meaning a year older than juvenile) sometimes only molt one or two tail feathers, a few inner primaries, and minimal body feathers, looking nearly identical to juveniles, so beware of scrutinizing every eagle. Anyway, I just wanted to talk a little about eagles, here are a few tails to check out, the first two birds are 2nd-years (note the several new sub-adult featherson the first bird but the second bird is only molting one tail feather), the 3rd bird has molted 3 times making it a 4th-year, and the last bird is an adult (but don't be fooled by that "slash" of white at the base of one of the tail feathers - adult GE feathers can still have a bit of white near the shaft (as can other species but often only seen in the hand).


15 Comments:
Blogger Mia McPherson said...

Thanks Jerry, awhile back I saw a Golden whose age confused me and eventually I was able to figure out that it was a second year bird. Having these images for reference in the future will really help.

I spotted two Goldens this morning over Antelope Island but they were hanging in the wind and were too high to get decent images of them.

September 18, 2013 at 10:35 AM  
Blogger Jerry Liguori said...

Just a reminder, forgot to mention in the post...birds molt at different rates depending on several factors, so birds can lag behind or molt quicker than others of the same age, which is obvious from the two SY birds. Also, I didn't show all ages here since the post was primarily just a note on how the tail is useful on birds where the wing molt is confusing.

September 18, 2013 at 5:13 PM  
Anonymous Dave Morrison said...

Good stuff, I always try to look at the wing molt in photos of Golden Eagles, it is hard to see but I will concentrate on the tail as much now. I would love to see one up close as in these pictures, is that possible? Where do you catch them?

September 19, 2013 at 7:00 AM  
Blogger Jerry Liguori said...

These birds were caught in various hawk migration locations by liscensed hawk banders. Many of the sites are public and visitors are shown the birds up close. The Goshute Mt. site in eastern NV is one of the sites where I go, but it is a bit out of the way and a hike in. HOWEVER, it is worth every mile!!!!

September 19, 2013 at 7:35 AM  
Blogger Bryce said...

Great post Jerry. This is some really valuable stuff. I'd love to see more posts about ageing birds in flight and in hand.

This blog is the best! Its almost like sitting at a site and having you explain every bird that is seen or caught!

September 19, 2013 at 1:57 PM  
Blogger Bryce said...

Valuable information, Jerry. I'd love to see more posts of ageing tips both in hand and in flight. I think we all can benefit from learning from you on topics like this. Maybe detailing some pitfalls or misconceptions.

I love this blog! It's almost as good as sitting on a ridge and having you talk about every bird that flies by, or is in hand. Love it!

September 19, 2013 at 3:48 PM  
Blogger Jerry Liguori said...

Absolutely Bryce!

There are misconceptions out there about ageing, sexing, and molt, even in published works. If there is something in particular you want to discuss, just let me know. You came across several things already...

Thanks for the input, I value your comments

September 19, 2013 at 7:24 PM  
Anonymous Ron Dudley said...

Great photos to illustrate your points, Jerry.

September 20, 2013 at 5:01 AM  
Anonymous Daniel S. said...

Cool post, I love this kind of stuff and want to learn more like it.

September 21, 2013 at 3:42 PM  
Blogger Jerry Liguori said...

Thanks Ron and Daniel

I'll try to post more!

September 21, 2013 at 3:46 PM  
Anonymous Matt Finch said...

And to throw in another wrench into the works,
When a bird gets sick and it's molt is interrupted or as is the case with West Nile Virus,
it throws off the process so much that I have seen and watched my friend's Juvenile Golden Eagle as it recovered from West Nile, which is now over 5 years old. She still has a 1st year feather, a 2nd year feather, a 3rd and a 4 year tail feathers thrown in by the end of its fifth molt. So aging eagles can get more complicated from the stresses of such an illness.

December 5, 2013 at 7:29 PM  
Blogger Jerry Liguori said...

Thanks for that comment Matt!

December 5, 2013 at 7:46 PM  
Blogger Vicki Lane said...

Hi, Jerry, I have some blurry pics of what I think is a juvenile Golden. taken from my fromn porch yesterday. I'd love it if you'd take a look and tell me what you think.
http://vickilanemysteries.blogspot.com/2014/03/whats-that-up-there.html

March 5, 2014 at 6:05 AM  
Blogger Jerry Liguori said...

Hi Vicki

It is definitely a juvenile Golden Eagle for many reasons, good job! But, the specific tail pattern is a great thing to look at for the ID and age.

Hope you keep checking in to the blog...

March 5, 2014 at 7:24 AM  
Blogger L. Broderick. WestCountyHawkWatch said...

Love it. thank-you.

February 22, 2015 at 10:07 AM  

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