Instead of doing a straight species ID quiz, I want to do a series of quizzes regarding age and sex of certain birds.
Here is the first Golden Eagle (I'll post a few more eagles after this). I photographed this bird in late fall, how old would that make it...in years or in age class terminology, either one. Its not difficult, so don't over-think it.
Labels: identification, Quiz, raptors
13 Comments:
Basic 1.
A 1st year bird.
A couple of primaries are beat up, but all the flight and tail feathers seem to be the same age, indicating this bird hasn't gone through it's first molt. If that's the case, it was a hatch year (HY) bird in the fall of 11 when you took the pic, and a second year (SY) bird as of 1/01/12.
I'm going with a juvenile bird. The outer primary feathers look worn and the amount of white in the primaries is minimal, but that's a secondary point. The trailing edge to the wing looks straight, showing no sign of molt. The amount of white in the tail points to a juvenile bird and with no molt, we rule out sub adult 1 and 2. So, I'm sticking with a juvenile bird. Great post!
Looks like a juv. to me. Jerry, could you give a breakdown of their first molt, as in, what time of year it starts and how the progression occurs? If I understand correctly, they don't molt all retrices the first year. Right?
Love these posts. Exactly the info. I need to be armed with. Thanks Jerry.
I'm going for sub adult 1 because of the neat white tail base.
Juv. 1st year.
Forgot to mention, you can "click" on the photo to enlarge
Jerry
Sub-adult 1 bird. They only molt a few wing feathers. You can just make out older juvie secondaries with some newer ones. So, not a juvie anymore, and also it looks like some primaries have new banding. So, the bird has molted once, but not to sub-adult 2.
Sorry, I used banding terminology. HY= Juvenile
Hi all:
Thanks for commenting! Telling juveniles form 2nd-year birds can be very difficult. From nice photos it might be easy, but in the field it is one of the most confusing ID issues. Just to be clear, a juvenile is a bird in its first plumage or first year of life...some people call them 1st-years, others say hatch-year. A bird in its second plumage (or after its first molt, in which it retains many juvenile feathers) is often called a 2nd-year, Basic I, sub-adult I. Some terms are more accurate than others for certain reasons, but regardless...
Our bird has molted at least once, we can see that on the body plumage, there are significant amount of darker (newer) feathers mixed in with lighter ones. On juveniles in fall, all the feathers are the same age. There are some new flight feathers as well, the outermost secondary (S1), the inner primaries (P1-4), and possibly the innermost secondary (looks to be new). The central and outer tail feathers are new as well (or at least one outer-the bird's left-and one central tail feather).
SO THIS MAKES OUR BIRD A 2nd-year.
A few things, juveniles can have grayish banding on inner primaries (usually the inner 2 or 3), so they can be mistaken for sub-adult feathers, make sure the feathers are newer ones (darker and possibly less worn) when determining this. Also, be careful, not all sub-adult tail feather show a defined grayish band above base the white. Basically, for sub-adults, If you can determine how many times it has molted, you can determine its age. It can be tricky, so know the molt sequence and know how to determine the different age feathers when dealing with the various sub-adult ages. 2nd and 3rd-years are easiest to determine, older birds get tricky at times.
I hope this was interesting, and I look forward to more posts like this. I am willing to share anything I have learned over the years, and hope it helps, so please be respectful and credit me if you recite it somewhere. Here is a link to ageing GE's from Birding June, 2004. I'm working on an article that is much more detailed and encompassing than this one, but its worth a look:
http://www.aba.org/birding/v36n3p278.pdf
Here is another very basic post if interested:
http://www.utahbirds.org/featarts/2008/AgeingGoldenEagles.htm
Hmm, I definitely didn't "over think" this... cuz I got it wrong. Didn't see the body molt in the small pic, but enlarging it still isn't definitive for my eye in regards to the flight feathers. I now understand why you always say "send me full resolution pictures". I'm chuckling at missing this ID on my ipad, but would be really disappointed if I pooched a high-res pic on a bigger screen, or with the bird in hand. Kudos to those who got it right. Thanks for the links.
Its tough to look at a small image, the high res are always best
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