Thursday, September 02, 2010

Where Do the Young Red-tailed Hawks Come From in Winter? The Views of Readers and Mr. Blakeman

Photo: Donegal Browne
The matter in question is what are the chances of survival for the Riverside young who have fledged so late in the season? Plus just where do all those juveniles come from who winter in Central Park and the other smaller parks in NYC? Are they local? Migrants?

From Anonymous in the comments section—
I'm curious as to why this year's babies would get a migratory urge. Last year's Riverside baby certainly didn't. Even if the birds aren't as adept at hunting as they might be, won't they realize that prey is all around them, and keep trying? Would their instincts tell them to leave an area which is rich in prey?

A happy addition to my previous comment: one of the Riverside babies caught a mouse today. Perhaps we have precocious youngsters.

Everyone is curious as to why Mr. Blakeman thinks these babies will migrate. We are used to seeing juvenile hawks here in winter, and the assumption is they are here because food is plentiful.

From Sally of Kentucky—
Of course I hope Mr. Blakeman is wrong, but of course I also know he is not, especially if the birds migrate. Your question is a good one-does the abundance of rodents and pigeons in NYC year round improve the chances that the young would stay and survive in the city? Rat poison aside that is. :( Not all juveniles leave the city, as you noted. We have seen Pale Male Jr and Charlotte, who appear so like their alleged parents, and we like to think that many of the hawks in the city are progeny of Pale Male. No one knows, obviously, and do we even know if they were born in NYC, did they migrate and return or winter over? Interesting indeed.

From Karen of Rhode Island
I am pulling for the Riverside babies surviving. They have already fledged, according to Lincoln's website.

Remember when their Mom was not supposed to be able to feed them because of her damaged beak? Yeah, Riverside hawks!

From Jeff Johnson

Ms Browne,
It's not such a stretch of the imagination for the late season Redtail fledges to winter in NY and take advantage of their parents continued help while taking advantage of abundant prey during their hunt training. My big fear is that they'll eat a poison tainted rat.

From Erik Sweig of NYC

I submit that the adaptable Red-tailed Hawk as a species, may have more choice in the matter of migration, or be spurred into migrating or standing pat by not only an urge but mitigating circumstances such as hunger or a high prey base.

My question for John Blakeman --

We often have quite a few juveniles overwintering in Central Park, where do you think they come from? Couldn't some be local young that have found the Central Park raisin in the raisin bread compelling and have decided to stay? I suspect rats being rats that there are new inexperienced ones being born just about all the time.

And his response to me--

The question of the origin of winter immatures, whether in Central Park, or here in northern Ohio is has the same unknown answer. I have a sneaking suspicion that these are birds from the north, who found prey on their way south and stayed around for the winter. I really think that the migratory urge is pretty strong for first-year red-tails and they really start to move in late September and all through October.

So in my area, I think most of my winter immatures were hatched in Michigan, or across Lake Erie in Ontario (although red-tails NEVER migrate straight across the lake. They cross the Detroit River and drift down the western shore of Lake Erie and then disperse E and W across Ohio when they hit Toledo.

The Central Park winter red-tails probably drift down from New England, or down the Hudson from Ontario, Quebec, and upstate New York. It's the rats that hold them there, surely.

--John Blakeman

After a good number of years of NYC hawkwatching and then comparing the behavior of urban hawks with those of rural hawks in Wisconsin for a couple of seasons, I've got some thoughts myself but I'm going to delve a little deeper first before expressing them while we all digest today's comments.

Anyone with other thoughts or other information please dive right in.

Donegal Browne


NYCBill said...

As an ex-NYC tour guide who used to ride around on a double-decker bus pointing out the sights, I was often impressed by the fact that the 927 hawks (PM and Lola) never seemed to go anywhere except across the park to the Beresford (next to the AMNH) for the winter. And that was to the west. I guess I supposed that RTHs didn't migrate very far at all... if ever.

Donegal Browne said...

Check the mainpage for my response discussion concerning RTH migration.