Friday, April 11, 2008

Out On A Limb--The Intrepid 79ers--Mai asks John Blakeman some questions.

Photographs by D. Browne
The Riverside formel sways in the breeze on a nest that is, there is no other way to say it, way out on a limb.

And as we've discussed before, not only is it out on a limb it is dangling above an access ramp to the highway. See the nest dangling between it's deciduous anchor and the evergreen?
Mom expells a pellet. The nest doesn't look quite so much like it is hanging out to dry from this angle because of the backdrop of branches but it's an illusion.
Frequent blog contributor Mai Stewert had a few questions about this nest and off they went to John Blakeman--

Hi John,

A couple questions --

Re the Riverside Park nest -- I've noticed in some of Lincoln's photos that the nest seems to be way far out on the branches, even on some not-very-large branches, and somewhat far from the trunk -- it seems almost to be suspended in space, almost at the end of the branches, which are neither as large nor as strong as those closer to the trunk.

(Lincoln Karim’s site is D.B.)

This can best be seen in Lincoln's photos of March 7, 13 & 16.

I've been wondering whether this nest might break the branches . . . and come tumbling to the ground? What do you think? Anyway do you think the RTs built the nest on this part of the branches, rather than closer to the trunk, on more sturdy branches?

Also, re the CPS pair, PMJ & Charlotte, I never understood why they abandoned their first (that we know of) nest, on Trump's bldg on Central Park South, which had worked so well for them (and us, as Lincoln was able to get great pix!). I liked Donna's posting after your comments on her website this morning, but nevertheless, their new nest location does seem a little weird.

Do you have any idea why they would have abandoned that first nest?

Thanks so much for all your contributions, and

With fingers xxxx'd for PM/Lola,


And John Blakeman's response--

The Riverside Park nest will not break the branches. It's no heavier than the snow and ice such a tree would encounter in a severe winter storm. The smallish branches holding up the nest will not break off, I'm certain. (I heat my house primarily with wood that I harvest, and am familiar with the strength of such limbs on trees.)

You asked the greater questions, "Why did the Riverside Park park pair elect to put their nest so far out on such meager limbs, and why did the pair now on 7th Ave choose that strange site, when things went better back at the Trump Parc ledge?"

I've seen these flimsey and poor-sited nests many times. In virtually every case they are by young, inexperienced birds. But the 7th Ave pair are now young adults, with several years' experience. They, I would think, ought to know better. But what do I know? I'm not a Red-tailed Hawk, a species whose thought patterns are so often an enigma. Just why the 7th Ave pair went to that totally atypical site is the strangest thing of all. Inexplicable.

Why did the Riverside pair build the nest so far out, away from the trunk? I just don't know why nests are built where they are. And I don't think the birds know much about this, either. At the start, in winter, when the first sticks are brought in for the initial nest building attempts, it appears that the birds often put sticks in various spots before finding a final one. Recall that the 927 pair actually put some sticks way up on the Beresford. That was not a new nesting attempt, and there was no intent to abandon 927 Fifth Ave. But in winter, the birds have an instinct to carry sticks around and place them in what they think might be likely nest sites.

I'd sure like to know what prompts the selection of the final nest location. Nests (at least out here in rural Ohio) seem always to be in usual and expected locations, either at the edge of a woodlot, in big tree in a meadow, or sometimes in the center of a woodlot. Red-tail nest sites have a typical "look." But why the birds gravitate to these areas is beyond my understanding. There is a high degree of randomness and chance, balanced by particular site features the birds tend to prefer.

So far, I've never been able to come up with any nest site formula, just generalities.

And yes, no one is wishing better for the 927 nest than I, inasmuch as I so strongly suggested all that was done so expensively there to rectify the nest cradle problems. Right now, everything is on the line. If the eggs don't hatch, I may have to slink away quietly.

--John Blakeman

Now time for my two cents worth--Why did Charlotte and Pale Male Junior move? Exactly what the cues were I don't know, but I do know that the Trump Parc nest failed far more often than it was successful. In fact we only know of it being successful once.
Without pigeon spikes to keep the twigs anchored, anytime there was any wind to speak of, much of the nest just blew away. Eventually with no bowl to hold them, the eggs would roll off the edge of the corbel. Year after year Charlotte stuck tight, getting drenched in rain and buffeted by wind. Junior diligently hunted, brought his mate food and sat the nest on Charlotte's breaks. They did the best they could but with the eggs blowing off the nest or sitting with Charlotte in a puddle of water every year, in the end there was never an eyass to show for all the sacrifice.
In 2005, the first season that Pale Male and Lola's nest failed after the latest destruction of the nest, we began to watch Charlotte and Junior. Not that you could really see much, just the switching of the parents on and off was all that was visible from the ground. Eventually they failed as well--yet again. And the Hawk Watchers began to disperse.
Then word came to Marie Winn, , from Veronica, who had a view from her apartment across the way, that Charlotte and Junior had returned to the nest. Marie called me to ask if I'd go take a look.
Had they double clutched?
I began to stake out the southern section of the park. Indeed, the Red-tails were going in and out of the nest on Trump Parc. It was late, very late in the season and besides they'd never managed a hatch up there before. Why torture ourselves? Was this just more failure waiting to happen?
Besides that, the experts felt that even if they were successful in having a hatch, there wasn't time to allow the eyasses to learn enough to be able to take care of themselves come winter.
We didn't care. We were going to watch anyway. Little Hill, near the southern wall of the park became the new Hawk Bench. Only without a bench, or a bathroom, or a restaurant.
We didn't care. We had hawks to watch.
That summer was a scorcher. There was a drought and Charlotte suffered up there with her dark feathers in the blazing sun but she sat. They did all the things they'd done before but this time...It worked. Big and Little hatched.
And to make a long story a little shorter and to save the adventures of Big and Little for another day, suffice it to say everything went swimmingly. They fledged, they grew fast and strong and yes, their parents trained them well and they did make it through their first winter. Hooray.
The next year, 2006, the Trump Parc nest failed again. I've always thought that the difference was the drought and lack of thunder storms, high winds, and drenching rain. Whatever the reason, after yet another failure following their first success (I think their first success anyway), Charlotte and Junior moved to 888 Seventh Avenue.
I think they moved because after their success, they were being cued somehow that something was wrong. There are supposed to be babies at the end of this process. Something clicked somewhere, hormonally or where ever and they had an urge to move.
They certainly picked a spot out of the wind and rain this time, though I'd not thought about it quite that way before. Does certain cuing change their order ranking of nest site criteria? Good question but no answer.
We'll just have to keep watching and see how it turns out.
Donegal Browne
P.S. Up tomorrow, some of the things that we in Central Park didn't know were going on around town when it came to Red-tails in 2005.

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