Friday, January 14, 2005

A New Letter From John Blakeman About Young Hawks

A New Letter From John Blakeman About Young Hawks

Marie,

I read Lincoln's posting this morning on his website describing his sighting of another red-tail in Central Park. He recognized it as a young bird, but pondered whether it hatched in 2004 or earlier in 2003.

As a help in "aging" the red-tails now being seen ever more frequently in Central Park, I sent to Lincoln the following field marks. For those who see new red-tails visiting Central Park, here's how to determine their ages.

Birds in Their 1st Year (from fledging in Spring through the first molt in their second summer) -- These hawks look like red-tails, but don't have red tails. The tails are brown-banded, matching the brown color of the back. They also have very prominent dark belly bands, a belt of dark feathers across the abdomen. Their eyes are a dull, light yellow, never dark.

Birds in Their 2nd Year (after the second summer molt, before the completion of the third-summer molt) -- All of these will have a red tail (or a mixture of old, un-molted brown feathers flanked by new red feathers). But the eye color will vary from a slightly brown-tinged yellow to a slightly darker brown. The iris will never be completely, uniformly brown as in full adults. It wll be light-colored, but not as bright as first year birds. Yellow-eyed, red-tailed birds are always in their second year.

Birds in Their 3rd Year -- This is where it gets tricky. Third year RTs have the red tail, of course, and their eyes are dark brown, similar to fully-mature adults. But almost always the iris is darker brown at the top of eye compared to the bottom. Third year birds have a remnant hint of the immature yellow at the bottom of the eye. If you see a dark-eyed RT, but there is any variation between the darkness of upper and lower portions of the iris, it's a bird in its third year. These differences can be rather subtle, so take care.

4th Year and Older Birds -- These marvels always have uniformly dark irises. After the third year, it's very difficult to assess a bird's age. There is one field mark that we believe to be true, but don't have really good data on. Watch your birds and see if you see this phenomenon.

We see old, successful, mature adults sitting around the countryside that don't have the usual dark belly band. It appears that some, maybe most (but certainly not all) older birds tend to lose the dark feathers on the belly as they age, probably well after five years. Certainly not all adults lose the band as they age. I had a 16-year old bird who looked like she was in her fourth year.

Obviously, to properly discern iris coloration, one has to telescopically zero in on a perched bird. A pair of binoculars is often insufficient to separate third year birds from older ones. A spotting scope is best.

Hope this information is helpful.

Sincerely,

John A. Blakeman