Wednesday, January 30, 2008

John Blakeman Comments--Twice and Lola Watches the Work--INTENTLY

Lola on the edge of the Woody building adjacent to 927 Fifth Avenue in the drizzle, keeping an eye on the workmen on the swing stage. And hence the answer to Bethany of Ontario's question.

Bethany asked, "In the last photo of your post, Lola has her back turned while Pale Male is on the nest. Did she stay that way the whole time the men were working?" (See next post down to view the photo.)

No, Lola was on the job watching every move the workman made like, well--a very watchful hawk! She is the closest she can get to them without being on 927 or the swing stage itself. She is also much higher than they are so that if she needs to go after them she'll have a dandy swoop going before she gets there.

If Lola had decided to go after this worker, he is pretty much a sitting duck with nowhere else to go besides throwing himself flat. Hence the reason for those black "eyes" on the workers helmets. John Blakeman's explanation is below.

But first the other topic of Mr. Blakeman's comments the spikes. Where are they and why might they be bad for the eggs.

See the spike just to the left of the middle egg. There are many others which aren't so obvious. They impeded the rolling of the eggs and wicked heat from the nest bowl. Also they no doubt poked Pale Male and Lola when they sat the nest, keeping them from completely enveloping the eggs with feathers and in Lola's case as she has a brood patch, getting the eggs up right next to her skin.

Here is John Blakeman's diagram of spike ends he could see in my photo of the eggs and of the bare area of the carriage.
The "Eyes" on the hard hats.
As the questions had begun to pour in into Marie's website about just why the spikes were a problem and other sundry issues, John Blakeman wrote two pieces for Marie Winn, author of Red-tails in Love and the upcoming Central Park After Dark (See links column for a link to Marie's wonderful website ) and now that I'm back to the keyboard, I see the questions have begun to pour in here as well. So Mr. Blakeman has kindly sent me his comments for Marie, which should help the questioners here as well. Here is Blakeman Comments Number 1---


The large dark spots on the backs of the hard hats were a suggestion of mine. They are made to look like two large eyes peering back into the sky.

When at a nest, Red-tails will often dive at a human interloper, occasionally even striking the person on the back of the head, shoulders, or middle of the back. But if the person turns around and looks at the attacking hawk, the bird turns away, knowing that the interloper sees that hawk and will defend himself.

Fortunately, there apparently were no aerial attacks from Lola or Pale Male. The eyespots on the hard hats may have helped prevent such flights. The last thing anyone would have wanted would have a technician getting a multitude of 2-inch needle-sharp talons embedded in his scalp. Our birds had the good sense, perhaps prompted by the suggested eyespots, to remain remote and distant.

Had the spike removal waited just a few more days, the hawks could have been far more defensive. As observers of this pair surely have noted over the years, activity at the nest really begins in earnest in February. The birds are detecting increasing periods of light each day now, and that starts the breeding and nesting hormones flowing.

Let everyone be assured that the nest will now be refurbished by the pair in the usual and typical manner of mature Red-tail pairs. The birds won't even know that the spikes are removed. Things will go on just normally now, with no loss of incubation heat, and equally important, with proper egg rolling.

And the removal of the old eggs, as I've indicated to Donna Browne, is also a very helpful development. In wild Red-tail nests, old, unhatched eggs virtually never survive an entire year in the nest. Raccoons eat them, or they just rot and blow out of a less stable tree nest. With the eggs up there now, Lola would have been impelled to begin to sit on them, quite prematurely. Of course, she will naturally spend extensive periods of time sitting on the empty nest. But without the old eggs up there, those periods of bare-nest sitting will be reduced and will not impede normal get-ready-for-eggs preparations, whether physiological (hunt to get nutrients to make eggs), psychological (be available for frequent sex-inducing flights and copulations), and finally, thermal and structural determinations, (to affirm nest construction suitabilities).

I'm so pleased to learn that this crucial project went forward and came to some useful completion -- just in time, too. I commend everyone who brought all of this together, especially the people at NYC Audubon. It's one thing to educate the public on natural resources and conservation problems, which Audubon intelligently does. But it's another matter to step forward, commit institution resources, and actually get things done. Words can be cheap. Rectifying difficult conservation issues can be expensive, as this surely was. Perhaps readers should personally commend NYC Audubon for their foresight and execution of this extremely difficult program. Well done, all.

Like everyone, I look forward to seeing more photos of the completed spike removal.


John A. Blakeman

And here's Blakeman Comments, Number 2---


The attached photo indicates the problem with the pigeon spikes. It was taken by Donna Browne in early January. I entered the photo on my CAD program, zoomed in, and placed a red dot over each of the visible spike tips. Without this magnification and spike marking, there doesn't seem to be much of a problem.

But it was this marked photo, I believe, that sealed the necessity of getting up to the nest and removing the spikes, at least the ones directly in the center of the nest, in the lined nest bowl, where the eggs are incubated.

The red dot just to the left of the left-most egg is revealing. Not only is the prong sticking up into the space where the eggs would have been rolled (impossible because of all the protruding metal spikes), but the closest magnification (here obscured by the added red dot) reveals that the spike shaft actually extends directly to the right, under the egg. The egg is actually wedged or perched right upon this metal spike's shaft.

The red dot immediately to the right of the eggs also appears to mark a spike that bends back, directly under the eggs.

Actually, there were almost surely many more spikes slightly buried under the lining material, which probably expanded during summer rains and wind events. Back in March, when the eggs were laid, it is very clear to those of us who have seen Red-tail eggs and nests that the prongs both prevented proper rolling (a crucial factor in egg hatching) and they also directly touched the resting eggs, wicking away incubation heat to the metal cradle frame and screening below.

Both of these now-obvious factors, the eggs resting on the spike shafts, and the fact that the spikes extended up above the nest lining, thereby precluding proper rolling, virtually assured incubation failure.

Once again, there are three essential factors in successful hawk egg incubation. One, humidity and moisture loss from the porous eggshell, was not a factor. Lola's naked brood patch took care of that factor. But keeping the eggs at sufficient, enduring temperature, and properly and frequently rolling them, were both impossible with the spikes extending into the egg space, as I previously contended for a year or more.

Now, with the spikes in the central bowl gone, the eggs will not be a few degrees too cold in cool March nights way up there above Fifth Ave. And when Lola feels a compunction to roll the eggs of her developing children, she will be able to do that naturally and instinctively. She will be able to push an egg outward, spin it around, and then nudge it back into place under her brood patch. Before, the spikes absolutely prevented that.

Again, in summary, originally the eggs became lodged between the spike shafts down in the lining, thereby precluding proper rolling and temperature maintenance.

Now, I think we have a great chance of seeing eyasses once again take to the skies above Central Park. Let everyone rejoice when that happens!

--John A. Blakeman
Keep scrolling on to the next posts for more on the Pale Male Nest Fix
Donegal Browne

No comments: