Originally Posted by
John Chardine
That's an interesting twist Roy! I see now what you were getting at in an earlier post when you said this bird was adult. First, the phrase "first year adult" is somewhat oxymoronic, i.e., I don't think it can be both based on what I know about timing of moult in these species. Assuming Rick's images were taken recently (note to Rick- important to mention dates images were made!), the first year bird in the OP fledged in summer/fall of 2008 which would make it a few months old. The bright yellow eye of this bird supports this age estimate, although rarely, 2nd year birds will also show a yellow eye (see Snyder and Snyder 1974, Condor 76:219-222). According to the Birds of North America account of the Coopers Hawk, the juvenal plumage lasts until about 11-16 months of age at which time the bird experiences a complete moult to adult plumage.
John, yes my explanation was indeed flawed. The bird would just be finishing the moult into adulthood.
So, if you are saying that the bird is in adult plumage then it has to be in its second year of life, in this case fledged in summer/fall of 2007. As mentioned, a bird this old could still have a yellow eye but it is rare. Females apparently take longer to attain a red eye than males, so if this is a yellow-eyed adult, then it is much more likely to be a female, which also implies that it should be a relatively big bird, which, based on Rick's comments, it wasn't.
The eyes don't magically turn a different colour when the moult is finished or nearly finished. Some change ,sooner or later than others. It, judging the age through the eye colour, is a generalization. If you look at the pics you posted of the immature coops you will see one pic where the eye colour of one of the birds is a deep amber colour not yellow, but that doesn't mean it's an adult.
As to Rick's later images, this bird for sure shows the marks of an immature Coopers.