Wednesday, March 9, 2011

Aging Female Kestrels

Click on photo to enlarge


I thought I would share my observations of how I age female kestrels, since it seems to be hard for a lot of people. The sub terminal black band being close to equal size to the bands above it can be a good indicator of passage in a lot of birds but some, like the one above, its pretty hard to tell. 

I've trapped a bunch over the past couple of years and I only counted passage by stress bars across the tail, then I compared them to known hags. There are a couple of stand out indicators between the two. At least from the birds I've trapped in Oklahoma. One is the overall color. Passage birds are a dull orange compared to hags that are more of a reddish orange. The black markings on hags are much sharper than that of the passage birds. The most distinguishing feature that I have noticed is the color of the primaries and secondaries. On the hags they are almost black and on the passage birds they are more brown. Also the Hags have a distinct white trailing edge to their primaries and secondaries, where the passage birds have a more tan trailing edge. 



-RVZ

4 comments:

steveo_uk said...

Cool post keep them coming Ryan ! Have you got any pictures of there wings and underside as well ??

Ryan said...

I don't but there really is not much difference between the two on the underside.

Doug said...

Good post - I'd like to borrow the picture if I may

Ryan said...

Sure Doug no problem