Thursday, December 15, 2005

Blakeman on Pale Male & Lola's prospects this year

Here's website correspondent Mai Stewart 's letter to John Blakeman and his response:
Hi John,
I've been noticing the gradually increasing hawk activity (as reported on the websites) -- and had a question re the state of the nest.
You may recall that a few weeks ago Marie posted on her website 2 pictures of the nest -- one was of the nest before it was destroyed and subsequently rebuilt, and the other pix was (I think) of the nest as it was a few weeks ago, including the fact that the hawks have been slowly but diligently working to add new material to build it up.
A couple questions have come to mind, following this and other reports (as well as Donna Brown's, yesterday) -- first, altho the nest looked better a few weeks ago than last winter, when the eggs failed to survive, it still looked a little skimpy to me compared to the way it had looked just before it was destroyed, when, the previous spring, the eggs had survived and chicks had been born successfully. So my worry is, even tho the nest is getting bigger + better, will it be sufficient this year to cover the pigeon spikes and enable the new eggs to survive and bear chicks successfully?
And, I've been really amazed at the bonding between PM + Lola, and their continued attention to this nest -- even tho things didn't work out last spring -- is this usual in RTs?? Do they mate for life -- at least as long as one of the pair survives -- are they generally monogamous, and so faithful to each other after their first bonding and breeding of chicks?
I look forward to your thoughts!
Thank you, as always,
Mai Stewart
I, too, am a bit concerned about the state of the 927 nest. It's really good to see that Pale Male and Lola are incidentally bringing new twigs to the nest. But I fear that once again, they may fail to get the bottom of the nest depression sufficiently above the protruding pigeon prongs. The issue is this.
Last year the birds failed to create a nest deep enough to suspend the eggs above the prongs. The eggs never hatched, either because they were punctured at the end of incubation when the shells become thinned, or perhaps because the metal of prongs conducted heat away from the eggs. Because the adults were experienced, nesting should have succeeded. The low stature of the nest seems to have been a major factor. And it's still too low.
Here's what I'd want to see this year. For the next few weeks, until things really pick up in January's increasing day lengths and elevated nesting hormones in the adults, there is not likely to be any substantial nest activity. The insertion of a few scattered twigs each day right now is just pro forma stuff, a result of the abundant food the birds have. Out here in wild rural areas, winter red-tails seldom, if ever, spend time and energy with nest twigs. Food is harder to find and capture than in Central Park. We don't have succulent rats scampering around, as apparently is the case in portions of Central Park. In winter, our rural birds have to spend most of their waking hours sitting and hunting the much smaller meadow voles. They don't waste time and effort on the nest just yet. The fact that CP red-tails are playing on the nest indicates the prime availability of food there.
But let's see what happens to the nest in January and February. I fear that the worst could recur, that the birds would once again build the nest only to slightly above the prongs. As I've mentioned before, it appears to me that red-tails build their nests only until it feels rigid. They don't build it to any predetermined height or thickness. They just keep plugging in sticks until it finally feels solid when then squat down on the nest and flail it a bit with their tucked-under legs. When the stick pile stops shaking, when the pile feels compact and in place, the birds think nest building is done. It's then just a matter of bring in the loose lining materials.
If this happens again, and I fear that it might, the new eggs won't be much higher above the prongs than they were last year, with the likelihood of the same result.
The better result would be if the birds somehow get the pile of twigs above the prongs before serious nest building begins in late January and into February. If that happens, the elevated twig pile will not be supported by the prongs beneath. As the birds sit on the taller nest in January and February, their instinctive leg motions will tend to spread out the new loose pile. That will be a powerful prompt to bring in lots of new sticks, to create a more typical red-tail nest.
If the birds can get the sticks above the prongs early in the nesting season, they will be prompted to complete the structure in a typical way. Red-tail nests out here in Ohio oak trees are typically 14 to 24 inches deep. Fourteen inches of sticks at the 927 nest would keep the eggs above the prongs.
So, let's see how deep the pair builds this year's nest. If in February it's still just above the prongs like last year, things will likely go wrong again. If the nest takes on a more typical bushel basket form, things should go well.
It's still too early to worry about this. As before, we'll just have to watch what the hawks decide to do.
You asked if the bonding, the "pair love," is normal, given all the difficulties they've encountered. Yes, it is. Red-tails generally mate for life. Pale Male and Lola don't fall asleep each night lamenting their failed efforts last spring. They just go about their activities prompted by genes and instinctive behaviors, which for this species (and most other raptors) causes strong pair bonding, not matter what else happens.
As romantic or poetic as it might be, to see the pair bonding of this pair as an exemplary model for humans, is a biological stretch. They are bonded because this noncompetitive, mutually-helpful hunting and nesting arrangement works best. Birds that didn't have these behaviors in the past encountered all sorts of difficulties and they either died off, or at least had few offspring to pass on their peculiar genes.
It's classic natural selection, the survival of the "fittest." For me, this is a great natural spectacle in Central Park. Astute observers, like yourself, are able to closely observe the forces and events that define the lives of these great predators.
The new nesting season is beginning. Keep me posted.

John A. Blakeman