Sunday, September 26, 2010

Sandhill Cranes, Blakeman on Juvenile Red-tailed Hawk Fall Behavior, Owls in Tulsa, and Birding Binoculars

The Thresherman's Park Sandhill Cranes in flight.

Here they are again, and I was having a heck of a time figuring out who was whom at first with all the contrast. More pics of them in another post attempting to get organized for draft flying. At one point there where three that looked literally on top of each other.
As you can see they are draft flying with the strongest bird in the lead. One of the juveniles is a much weaker flyer than the rest and sometimes acts quite a bit younger than the other. A late egg?
At any rate, that is Jamie in the lead, missing the primary, which makes sense. But where does Mom come in here? From scrutinizing which two have the fuzziest necks, Claire, with a smoother neck, is the bird flying second after Jamie in the bottom row. Which leaves the two juveniles--the one on top and the third in line on the bottom.


Doubtless, there are winter immatures in NYC each winter. The question is whether or not these birds hatched there, or are they migrants from farther north?

On the basis of studying the red-tails in northern Ohio, at a similar latitude, I think that most winter immatures were hatched to the north and are spending the winter at the lower latitude. The locals, too, will spend the winter farther south, at a latitude south of their nests.

The availability of winter rats would be the main attraction that terminates the migration of these (putative) New England and Upstate red-tails in Central Park.

Of course, the exact answer to this question can only be resolved with banding.
--John Blakeman



The question of immature migration continues. A few further thoughts on the matter.

First, it is very clear, both here in northern Ohio (at virtually the same latitude as NYC, but ecologically very different), virtually all experienced adults remain through the winter. They’ve mastered all that is required to survive, even thrive, in the winter months. They’re very aware of local prey populations. They’ve got everything figured out and have no compulsion to move south during the winter.

That’s not true a hundred or more miles to the north, where winter days are even shorter, colder, and with fewer available prey. The northern birds are required to move south, even the adults. The Ohio and NYC adults are not. There is no controversy regarding these observations.
But the question of birds-of-the-year in their natal (local) territories through the winter continues.

Does this happen, do local immature hang around for the winter? Surely they do, both in NYC and I’ve seen it here in northern Ohio. But at least here, it’s rare. Our rural birds begin to drift south late in September and really begin to move out in October. We do have immatures that winter here, but they are mostly from the north, residing in winter territories that no other hawks are using, or they tend to congregate almost socially in a few prime habitats with prey, local state wildlife hunting areas where voles abound.

The urge to migrate is not an endocrine function. It’s purely psychological, prompted by declining day lengths. Falconers who fly red-tails, as I do, are well aware of this phenomenon. It’s one of the problems with training and hunting with summer- or fall-trapped immature red-tails. Falconers are wise not to fly their birds on windy, sunny, blue-sky days in October. A well-trained immature red-tail in conditions like these are very prone to taking off and soaring up into the sky. Soaring red-tails are virtually never hunting. They are merely drifting around, playing in the wind. In the fall, immatures tend to get up a thousand feet or more and then just turn south, never to be seen by the falconer again.

They see all the other red-tail migrants all over the sky, many much higher. The local immatures seem to want to join this south-bound aerial parade.

It is very possible that a number of the immatures seen each winter in Central Park are local birds. Nonetheless, the migratory urge is rather strong.

As you mentioned, it would be so helpful if these birds could be banded. The same questions apply down at The Franklin Institute nest in Philadelphia. But that nest is a bit farther south, where migration is less urgent.

Actually, with modern digital cameras and telescopic lenses, comprehensive photography of local immatures in summer could reveal their winter presence, with detailed examination of feather patterns.

–John Blakeman

(My response to come. D.B.)

From the comments section of SATURDAY, FEBRUARY 06, 2010
Red-tailed Hawk Update: Kay and Jay of Tulsa, Plus Owls

Comment posted, Saturday, September 25, 2010 12:54:00 PM EDT,

Anonymous said...
There are red tails that live on the eastern edge of Whiteside park. One was making a lot of noise this morning and we stopped to locate him/her and we saw that there was a huge owl sitting quietly and almost completely hidden on a branch. We have seen and heard the juvenile red tails for some time but I had no ideal that owls that big lived in town. Any advice on small fairly inexpensive good bird watching binoculars would be appreciated.

Dear Tulsa Anon,
Amazing the number of large birds we suddenly see once we start looking isn't it? As you say the Owl was almost completely hidden does that mean you weren't able to get an ID on it. Or were you?

As to good reasonably priced birding binoculars, I've sent out some emails to a few folks that keep their eye on that sort of thing but in the meantime--
Get out your yellow pages and look to see if you've a camera, binocular, etc. specialty store in your town or near by. Go in and browse. Everyone's eyes, face, and hands are slightly different.
For instance some binoculars are better for glasses wearers than others, there are many personal variables.
Be sure to tell the clerk you looking for birding glasses not something to watch football with or even a multi-purpose pair. I've found that multi-purpose in binoculars means they're not terrific for any purpose. Then have the clerk bring some out and let you look through them, preferably out a window or other distance. See how the modifying bells and whistles work for your fingers, how do they feel in your hand? Is there a color shift? How crisply can they be focused? Is there a bit of purplish glare around things that are backlit? Is this pair something you'll want to carry around with you all the time?
Remember you aren't buying quite yet you're browsing. Make a few notes on your favorites w/price. In the meantime we'll see what advice comes in via email. After which time you can not only search out just the right pair for you but also do some comparison shopping to get the best price.

Donegal Browne

P.S. Ah ha! Just realized that at least in these photographs the Sandhill Crane adults have their feet more pointed and their legs touching along their length while the juveniles do not. Much easier to look for than fuzzy necks if, at least for the moment, the leg position holds true.

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