Friday, February 01, 2008

PART 2 of the Fix

All Photographs: D. Browne
Where we left off-- The swing stage had gone down to pick up the engineer.

10:52AM Pale Male to the nest. He finishes his midpoint investigation. He then flies off the nest

11:04AM The engineer arrives at the nest.


11:07AM They check the left side of the twigs for spikes.

11:09AM The worker on the right gets a call on the walkie talkie from Jeff Kollbrunner who is directing the clipping of the spikes from his view standing on the Fisher Terrace.

11:12:33AM All spikes and rough spots are cleared from the untwigged portions of the carriage on the left side.


11:13AM More instructions by walkie talkie.

11:18AM Spikes removed from left twigged section?

11:20AM The second worker receives instructions.

11:21:20AM Spikes removed from right twigged section of nest.

11:21:52AM More spikes from same.

11:26:18AM Right end of untwigged section of carriage is cleared of spikes.

11:29AM The engineer checks the left nest and bowl for spikes.

11:31AM Note the spikes in the hand of the middle worker. More clearing of right bare section of carriage.

11:37AM More directions by walkie talkie.

11:39AM Back now to check the left side again.

11:40AM The swing stage starts to descend slowly. A view of the nest after clipping.

12:10AM Pale Male sits on the railing of the Stovepipe building watching the swing stage.

12:34PM Pale Male flies over to Linda, tucks his foot up and checks out Lola and the nest.

12:36PM Lola on a high point of the Woody Building.

12:37PM Lola can see the swing stage and what is happening on the roof of 927, while Pale Male keeps tabs from the other side, perched on the window railing of Linda.
Then Pale Male and Lola take to the sky and begin to circle north, intertwining their flights, and curving higher and higher out of sight.

Keep your fingers crossed.
Donegal Browne

(To access the most recent posts, click on Palemaleirregulars at the top of the page.)

Protecting the Nest and 2007 Eggs Before Retrieval

There was activity on the roof of 927 Fifth Avenue on January 28th. Spring is coming so Pale Male and Lola took special interest in it.

3:29:14PM A workman appears above the parapet on 927 Fifth Avenue.
3:31:08PM With the hormones flowing, the hawks are far more protective than they had been just a few weeks before when the nest photographs were taken. Now, when the workman appears, Lola takes over the nest in a hurry and Pale Male flies back and forth over the roof.

3:31:48PM The workman goes lower, but not quite enough as his red helmet still extends above the parapet.

3:32:17PM Lola focuses on the bowl of the nest which contains last season's eggs.
I'm prone to believe that as the hawks are going to the bowl and looking at the eggs that they do note when they have been removed. The hawks don't display agitated or stressed behavior about not finding the eggs in particular but they do look for them and note their absence after they are removed the next day. John Blakeman disagrees. His thoughts are below at the end of the photo sequence.
Differing opinions are no problem at all. Differing deductions are a common occurrence with observers and something that feeds discussion, the journey toward more understanding plus better hypotheses for investigations yet to come. Discussion and comparison of all data amongst all involved is the life blood of useful investigation and relevant conclusions.

3:32:45PM Lola watches as Pale Male comes in for another pass, this one quite close to the workers heads. Despite how it looks, the workman can't see Lola from their view point and I'm not totally sure if they even realize that Lola is on the nest or that Pale Male is coming in yet again above their heads.

Another pass by Pale Male.

Lola looks to be covering the bowl itself from prying eyes. I'm assuming that is a built in response to seeing those objects in that nest position.

3:32PM Pale Male turns and goes for another look of the roof amd then heads NW.

3:32:33PM Lola watches him go.

3:34PM Lola leaves the nest.

Pale Male curves round Woody Building, and then he lands on the nest. He investigates the nest also looking around as Lola had, and did some staring into the bowl as well.

4:03:11PM The switch. Pale Male takes off from the nest and Lola comes back on.

4:04:01PM Lola investigates the nest, focusing again on the nest bowl.
4:04:19Pm Satisfied with the nest and no workmen in sight, Lola takes to her wings for a cruise in the sky with Pale Male.
These behaviors took place the day before the eggs were retrieved. Beyond the work that was done to the nest carriage, the egg retrieval had an even more immediate positive effect.
Here is what John Blakeman, who worked on early captive breeding trials of Red-tailed Hawks, had to say about why removing those eggs from the nest was so important.

I was pleased to learn that the workmen on the swing stage were able to completely remove from the nest the three remnant eggs from last spring. This was a very positive effort, for the following reasons.

Of course, it might seem that confiscating Lola's eggs, even at this late (or early) date might be disconcerting to her, or to Pale Male. With your photos of PM looking down into the now-empty nest you posed the question he might have been pondering, "Where's those eggs?"

But in fact, neither Pale Male or Lola would have pondered that question following the eggs' retrieval for analysis. While the eggs remained in the nest, they provided a very significant visual cue or prompt for the birds to begin incubation. As the reproductive hormones begin to flow, now that the days are getting longer, the birds will have an urge to instinctively sit on eggs, even prematurely.

In captive breeding experiments, we can dump a white tennis ball or chicken egg in an open nest, and in season the hawks will instinctively begin to "incubate" the objects.

That was the problem with leaving the old eggs in the nest. In late February and into March, weeks before this year's fresh eggs would have been laid, reproductive hormones would have compelled the birds to begin to incubate intently on the eggs they could see in the nest. Just how that, then, would have complicated the new eggs is unknown. But it couldn't have been useful. The nest could have ended up with six eggs, three old dead ones, along with perhaps three new, viable ones.

Lola doesn't have a brood patch on her chest or belly big enough to keep six eggs warm. I was concerned that even after the spikes would have been removed, the presence of six eggs would have compromised the proper incubation and turning of the three new good ones. The hawks couldn't have figured out which was which. They just sit on any white, round object that appears in the nest. Without the removal of the old eggs, it could have been six eggs, thereby disrupting real incubation.

So, it was a good thing the eggs were removed from the nest. The parents aren't sitting around asking each other, "Hey, what happened to those three old eggs that were in the nest all summer?" The birds aren't that cerebral. It's just, if it's there, sit on it. If it's not there, it's not there and there's nothing to worry or even think about.

Now, without the old eggs disrupting normal nest preparation activities, the hawks can go about naturally refurbishing the nest and its lining. When the first egg starts to descend Lola's single fallopian tube in March, both she and the nest will be ready.

--John Blakeman

The second half of the photos from Nest Fix-it Day still to come! As there have been questions, I hope they'll help clarify all the areas from which prongs were clipped.
Donna Browne

Thursday, January 31, 2008

Many Thanks and the Hawk's Eye View

A hawk's eye view of Pale Male and Lola's nest
(See one of the 2007 eggs peeping out just beyond the masonry. No wonder the eggs were still in the nest, there are very few angles in which a predator might see them. Smart parents, these hawks.)


Lending nature a helping hand

NEW YORK, NY – Spring spruce-up came early to the red-tailed hawk nest on the fa├žade of 927 Fifth Avenue. Scaffold workers, directed by New York City Audubon, repaired the nest cradle mounted atop a 12th floor cornice of the building. Although the work done required only a few hours, it could be critical to the birds’ ability to produce chicks this spring and in the years to come.

Pale Male and Lola, the beloved red-tailed hawk pair, have had no success hatching chicks since re-establishing their nest on the cradle in spring 2005. Prior to that date Pale Male and his mate produced chicks each year from 1995 through 2004 – a total of 26 hatchlings, of which 19 survived to fledge – making Pale Male one of the most successful red-tailed hawks ever documented. Concerned by the correlation of lack of propagation and construction, NYC Audubon enlisted four red-tailed hawk experts around the country to study the situation and present conclusions.

At the panel’s request, NYC Audubon arranged for two wildlife photographers, Jeff Kollbrunner and Donegal Browne, to take photos of the interior of the nest from the building’s roof on January 4.. Those pictures showed that stainless steel pigeon spikes extend above the nest material, posing a serious threat to successful embryo development during the 5-6 week egg incubation period. Birds must roll their eggs so that fluids within the egg are gently distributed and the tissues don’t stick together and form a dense mass. The erect spikes appear to impede this critical step and also to interfere with the hen’s ability to make proper contact of the eggs to her brood patch, keeping the eggs consistently warm. An observer reported that the hen’s brood patch appeared to be rubbed raw this past nesting season.

Braced with that evidence and the panel’s recommendation to remove the spikes beneath the nest bowl, NYC Audubon worked with various NYC authorities and the building’s coop board to obtain permission to remove the spikes from the nest cradle. The task was time-critical; early February marks the start of copulation.

"I'm so pleased to learn that this crucial project went forward and came to some useful completion -- just in time, too,” said John Blakeman, an expert on red-tailed hawks, and the author of NYC Audubon’s report . “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.”

“NYC Audubon has taken a brave and difficult step. No matter what the outcome -- and you never know in the unpredictable world of nature --we Pale Male and Lola fans will be forever grateful to them,” said Marie Winn, author of Red-tails in Love: Pale Male's Story. There is no guarantee that this improvement of the birds’ habitat will mean chicks in mid-April, as the recent lack of reproductive success may have other causes. However, as one NYC Parks & Recreation official said, “I’m hawkish about what we’re doing.”

NYC Audubon would especially like to thank the Richard Cohen and the Board of 927 5th Avenue, NYC Parks and Recreation Commissioner Adrian Benepe, and Sandy Fiebelkorn, a board member of NYC Audubon and the volunteer who coordinated this extraordinary effort.

NYC Audubon

And from the Hawkwatchers and all on this end, we would like to extend a big thank you to those mentioned above plus Red-tailed Hawk expert John Blakeman, Aimee van Dyne, NYC Audubon, and their Executive Director Glenn Phillips as well.

(They're are still more photos and details of the story to come. Stay tuned!)

Donegal Browne

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

NYC Audubon, Workmen, the Nest, Pale Male, and the 2007 Eggs

9 24 AM No hawks in sight, nor anyone else for that matter. It's cold, the pond is frozen over, and though the weather report predicted no rain until the afternoon, it very much is beginning to look like it isn't going to wait until afternoon.

10 12AM I'd been noticing that the pigeons kept hopping down onto the frozen pond at this point, they'd walk around a little, put their beaks to the ice, and then fly away again. Then I saw that this was the spot in which the sun hits first and perhaps there is also a flow pipe because suddenly it began to burble. It wasn't ice anymore it was liquid and the pigeons were mad for a bath. Though some people think pigeons are dirty, they'll bathe several times a day, even in very cold weather if given half a chance.

Then for no reason I could see, they took to their wings.

10 16 36 AM Perhaps it was this. The swing stage hired by NYC Audubon to hopefully work a fix on the nest was rising slowly up the front of 927 Fifth Avenue.

10 18 26AM Nearly there, the workman on the right gets on the walkie talkie to the Audubon person on the Fisher terrace, who is directing the work.

10 24 04AM After managing the swing stage into position, the workmen first take photographs of the nest.

Below: Hawk Expert John Blakeman took my photographs from the roof and marked the many visible prongs. These, along with the field notes that documented the post-carriage digging behavior of Pale Male and Lola, helped validate his long held theory that the spikes in the bowl may have been contributing to nest failure.

After photographing the nest, the eggs from 2007 are retrieved for testing. Note the upraised hand displaying an egg to those of NYC Audubon grouped on the Fisher terrace and the collection box held by the worker on the left.

10 40 AM After cutting some spikes from the bowl of the nest. Discussion ensues.

10 41 18 AM The swing stage descends to get the engineer.

10 52 08AM As soon as the swing stage seems truly gone, for the moment anyway, Pale Male lands an the nest and checks the bowl of the nest. Where are the eggs?
10 52 14AM He then looks into the bowl from another angle. Where are the eggs?
10 52 39AM Pale Male checks the territory. Then resumes his search.

10 52 50AM He then flattens and slowly nears the bowl of the nest. Is he concerned about a possible predator as he's not sure what is going on?

10 53 13AM He puts his head completely into the bowl. Satisfied that the eggs are gone flies from the nest.

10 55 40AM Lola keeps an eye on the rest of the territory. Vigilance cannot cease no matter what my be happening on the nest. There are the Kestrels which have been attacking today and there is the new breeding season ahead that must be safeguarded.

Donegal Browne