Saturday, April 29, 2006

And more letters about the nest failures

A recent spring migrant -- the Louisiana Waterthrush -- 4/27/06
photo by Bruce Yolton

Here are two letters I thought I posted a few days ago. Unfortunately I neglected to push the "Publish" button.

And talking about neglect: keeping up this website on a daily basis has been a great pleasure for me. But I have to put my present writing task on the front burner. I've been neglecting it. I'll try to post Central Park news as often as I can, but until I finish my book I may not update this page every day.

Arlene Katz writes:

Dear Marie

I'm thinking that these eggs must be collected and analyzed. The hawks are at the top of the Central Park food chain. What is in that food chain?
Thank you as always for keeping us updated.


Rebecca A. Fronk adds a new concern:

I have not been able to keep up with the NYC Redtail nests as much as I would like to, and was very surprised by the latest news that neither nest might have chicks this year.

Weather seems to be playing a part in raptor nest failures from coast to coast. Extreme fluctuations in temperature and heavy downpours have been experienced across the U.S. this season. Gone are the days where Winter eases into Spring and the weather stays on its steady course into Summer. Could these increasing raptor nest failures be a reaction to global warming, or are we just more aware of them as, fortunately, there is more interest and cameras focused on our nation's raptor population?

Again, I am sorry to hear of your sad situation in NYC. Hopefully a little miracle might happen or be discovered. I appreciate your efforts to continue to document your famous pairs of beautiful Redtails and enjoy viewing the photos and reading the updates when I can.

Best wishes - Rebecca

Friday, April 28, 2006

Blakeman says: Let's get real here

I appreciate the warm and laudatory comments you've posted.
But it's time that we all move forward in the observation and explanation of the Central Park red-tails. Yes, the CP hawks have been given -- quite appropriately, I think -- human names. But that's as far as it should go.
Let's get real here. These are birds, not humans. They have emotions, but they aren't ours. Their brains are wired very differently from us. They don't and can't think or emote like we do. Pale Male and Lola are not distressed in any way by their reproductive failure. They do not "know" that they should be feeding two or three little elevated mouths this week. They weep no tears over the loss of their offspring, both because they don't weep as humans do, and because they can't cerebrally contemplate the loss. Now, as always, the hawks are acting and reacting merely in response to the environmental prompts they immediately encounter. Yes, this is somewhat mechanistic, but that's the only way animals without complex cerebral cortices can act. Attributing human traits to these birds, being anthropomorphic, can be fun. But it should be confined to wonderful children's books, not used to explain the hawks' behaviors in the park.
In short, it's not inappropriate to warmly and emotionally identify with our hawks. I've been doing that since I saw my first red-tail on my grandfather's farm at the age of 13. But we must strive to accurately understand and describe what we see. I find that the birds' behaviors are even more engaging when explained by their unique hawk "lifeways," not as merely winged humans. For fun, we can attribute any sort of human emotion or motivation to these birds. But in the end, let's keep everything focused on the real science.
The Central Park red-tails will continue successfully reside in New York City. That's the real story. The how's and why's of it should be the center of CP hawkwatchers' efforts.

John A. Blakeman

Thursday, April 27, 2006

Disappointment tempered by acceptance

"magnificent animals continue to thrive...and thrill"
Lesser Scaup on Reservoir - 4/26/06
Photo by Bruce Yolton

Many readers have written in to thank John Blakeman for his latest posting [Tuesday, April 25]. Here are two:

Hi! I am crushed........but John Blakeman is absolutely right; these magnificent animals continue to thrive....and continue to NYC...and Central Park.

Penelope Bianchi of California

Dear Marie,

. . .[John Blakeman] puts the crushing disappointment into perspective. Our marvel should be of the fact that these "regal" red-tailed hawks can successfully occupy this territory; four adults can live, hunt, and sometimes even reproduce in CP. He reminds us of that there is so much we don't know and that beauty and wonder are there, as well as our heartache. If Pale Male and Lola, and now Junior and Charlotte, can bear this, then I will bear it also, and I will look to next year for babies. In the meantime, there is a lot of daily living that these birds will enjoy and we should watch and savor it.

There is a Jackie Kennedy quality to John Blakeman's words. I think of those gathered at the boatpond, waiting, (I would be there were I not here), with that dreadful hopeless feeling creeping into our minds, in the midst of our gaping silence, he gives us the courage we need.

Nan Holmes

Wednesday, April 26, 2006

From Today's New York Times

April 26, 2006

Like Chickens, Hawks Shouldn't Be Counted Before They Hatch

In a second blow to Central Park hawk watchers in a week, the eggs in a nest on a 35th-floor perch of the Trump Parc condominiums will not hatch, experts said yesterday.

"It is extremely unlikely because of time that has passed," said E. J. McAdams, executive director of the New York City chapter of the Audubon Society.

The Trump Parc eggs had been produced by the red-tailed hawks known as Charlotte and Junior, a male believed to be a descendant of the famous Pale Male.

On April 20, the society determined that eggs being tended by Pale Male and his mate, Lola, in a 12th-floor nest on the facade of 927 Fifth Avenue, at 74th Street, were no longer viable.

Of the two nests, hawk experts had considered the one on the Trump Parc building, at Central Park South and the Avenue of the Americas, to hold the best hope of hatching, since Charlotte and Junior produced two healthy offspring, Big and Little, from the same perch last year. Pale Male and Lola failed to hatch eggs a year ago after their Fifth Avenue nest was carted away by building employees, provoking wide protests. It was eventually rebuilt, in a protective cradle.

Mr. McAdams said the society and other hawk enthusiasts hoped to gain the cooperation of both buildings in investigating why this year's eggs did not hatch. He said efforts might be made to retrieve the eggs for analysis by a wildlife pathologist.

For now, however, the reasons that both pairs of hawks have failed to reproduce remains a mystery. "There could be so many reasons, it is just impossible to say," Mr. McAdams said.

Tuesday, April 25, 2006

A question and an answer from Blakeman

Pale Male bringing twig to nest - April 23, 2006
Photo by Lincoln Karim

Dear John and Marie,
As I was reading all the comments on today's website, the thought occurred to me that, after the first nest was destroyed and rebuilt by the RTs, it took 2 years before there were viable eggs and babies in the nest -- am I remembering correctly? Perhaps it's just the same this time around -- it'll take 2 years for the nest to become well-enough constructed and protected for the eggs to hatch again -- what do you both think?

Although we all are greatly disappointed with this year's non-hatching (for whatever reason's, including perhaps penetration by pigeon spikes), might it be that it's all part of the process of getting the nest to the size and density it needs to be in order for next year's eggs to be successful. This may be a gloomy thought, but perhaps w/ a silver lining --??
I've noted John's comments re the RTs looking down into the nest, as though an egg had hatched -- I certainly hope, whatever the outcome this year, that it will be somehow possible (even if a crane has to be hired!) (well, yes, expensive) to be able to look into the nest and retrieve whatever is left behind, to try to determine exactly why the eggs have not failed to survive again this year.
Any thoughts you have would be appreciated --
Mai Stewart
Yes, with each passing year more material should be building up at the base of the nest, elevating the useful, working central bowl that holds the eggs. But this base is composed only of nest lining material, not sticks, so it may never get elevated enough to rise above whatever metallic parts might be at the bottom. Lining materials are typically fine grass, moss, thin bark strands, and other similar things that don't weather so well during the year.

In wild nests, which are typically parked in the crotch of a tree, or in some regions in the West on a bare rock ledge, the sticks used to construct the nest are continually tucked inwardly to create a firm, un-wiggling nest. Then, nest lining materials are brought in and tucked into the bottom of the nest. The lining has to be replaced and refurbished each year as summer, fall and winter rains degrade the linings. The majority of the sticks usually don't have to be replaced. New ones are just tucked into the stick pile, making up for the older ones that soften and rot.

Remember, red-tails seldom use the same nest site year after year. Unlike Pale Male at 927, rural red-tails typically use a nest for just one or two years, then abandon it and build a new one a few hundred yards to a half-mile away, somewhere within the territory. This brings up the question of why Pale Male would elect to use the same nest site for over a decade. That seldom occurs in the wild. My only explanation for this lengthy continuity is that the 927 pair prefers to be high above the prolific activities of the ground. The parades of cars, people, dogs, and who knows what other ambulatory disruptions have probably driven both resident Central Park red-tail pairs inordinately high into the sky. In typical tree nests in the East and Midwest, red-tails build their nests usually between 40 and 60 ft off the ground, beneath the tops of the trees. The two CP nests are way above this normal nest zone -- far higher than I would ever have predicted. But they clearly like it way up there.

So, in reference to your good questions, what might be the probabilities of nesting success next year? I'd like to suggest that I know all about what's happened and have an informed, reliable outlook. But I've dealt with wild species long enough to know that they don't just act linearly or arithmetically. Yes, Pale Male should be successful next year, and so should Pale Male, Jr. But these things can never be assured. These are wild animals, subject to a plethora of known and unknown life history and survival factors. It's a crap shoot, and for reasons we may never know, the dies may not roll the ways we'd like next year. They sure didn't this year.

Now let me make a statement that might cause some to question both my expertise and my concern. Like everyone else, I'm distraught that things haven't turned out well at either nest this year. Thoroughly disappointing. But am I really concerned? Do I see any of this as portending the loss of Central Park red-tails? No, not so. As a wildlife biologist I've learned in over three decades of field observations that "failures" happen, more often than not for no good reason. The birds, as I previously claimed, did everything right. There should have been eyasses this year. But they didn't appear. That's the way nature is arranged -- not much concerned with the successes or failures of either individuals or entire populations within short time frames. The mere occupation of Central Park by two mated pairs of red-tailed hawks is sufficient enough. In decadal (or longer) time frames, red-tails have been very, very successful in Manhattan. I'm not going to get too concerned until two years pass without any resident Central Park red-tails.

I don't think that's going to happen. The remarkable thing is not that red-tails have reproduced in CP. That's an end result of the greater marvel, their ability to come into the park and so successfully adapt their hunting and occupancy behaviors to that unique environment. For me, that's the real, continuing story. The fledging of eyasses is an almost peripheral byproduct of the greater occupancy miracle.

So, let's not be overly depressed with how things turned out this year. Four regal red-tailed hawks will still be seen and marveled at by those with the opportunity to lift their eyes into the Manhattan skies. For me, the mere residential presence of these great birds in Central Park is enough. Nature has its vicissitudes, and hawk reproduction in the last two years has been nil. The adults are still with us, however, and that's adequate. Be thrilled once again when you see a perched or passing Central Park red-tail. Even without offspring this year, their nobility is sufficient. Let's learn from nature. Life can be hard and the lives of no one, human or animal, can always be assured. The lessons of former years, happily, were ones of rebirth and renewal. The lessons of the recent two seasons are a bit more weighty. Survival and reproduction for any organism is never assured.

John A. Blakeman

P.S. -- A cheap digital web camera could be extended temporarily on a pole over the edge of the 927 roof to get images of what's in the nest. No need for a crane or any other mechanical device. A laptop connected to a camera would work.

Monday, April 24, 2006

Ideas about the nest failure

Many letters focus attention on the new structure put up after the nest was removed in 2004 -- the so-called "cradle". Here's one , followed by my response, which in turn is followed by John Blakeman's response:

Dear Marie;

....from the information I've gleaned about PaleMale & Lola's nesting situation, it seems to me that the single element that separates them from other successful urban nesting couples, and also separates them from their own past successes, is the underdraft to their nest - specifically the egg-nest part. No matter how warm their breasts would keep the eggs, the open air from underneath would take temperature from the eggs from the bottom, by convection. ...

I don't know if there is a viable way to insert a windblock...perhaps the architectural firm that designed and installed the support/spikes could get out their specifications and make one for a perfect fit, and after the birds give up on this group, get in there as quickly as possible and insert and secure the windblock to the nest support.

Elizabeth Kyle
Galveston, Texas

Here's what I answered, followed by John Blakeman's additional comments:

Here's the problem with your idea: a nest in a tree [redtails' usual site] also wouldn't have a completely solid base as they happened to have on the window ledge. In a tree nest there are all sorts of chinks and holes where air can get in from underneath. But redtails are hardwired to line their nest in such a way that they can tell that no air is getting in from underneath. They'll just keep adding lining material until everything is perfect.

But...I agree that it MUST be something about the "cradle" they put up there, something that gives them a false impression of completion when the nest still needs more sticks or more lining materials. And another possibility, maybe there's a problem with the cradle material, which is not wood but steel. I'm going to pass this on to John Blakeman, your question and my response, and see if he has a response.

Thanks for writing!

Here's John Blakeman's response:


Your response to Elizabeth Kyle's concerns was virtually identical to what I would have stated, only to add that I've seen a great number of new red-tail tree nests that were so poorly built I could look up through the nest with binoculars and see bits of the sky above. Of course, none of these were successful. First attempt nests are frequently thin and leak air through them.

But more experienced adults create thick (10 to 20 inches or more) nests in trees. The bowl or cavities of these get densely packed with fine lining materials that seal out the rising cold air beneath.

The shallowness of the 927 nest is a concern, but it appears that the eggs there are warm enough to develop and pip. If they eggs were dead or unfertilized, the adults would just sit on them and continue to incubate into April. They wouldn't stand at the edge and look down into the nest at anything. Because they appeared to do that this year, it's probable that the eggs developed and initially pipped or hatched (but perhaps too quickly, causing the eyasses to die from lung desiccation).

The 927 nest is shallow, as you stated, because the adults stop adding sticks when they feel that everything is solid and firm, the result of the pigeon prongs which hold everything together.

Once again, it's good to have such intelligently questioning readers.


--John A. Blakeman

Several readers have written to ask about possible rat poison or pesticides that may have affected the egg development.


About chemically testing the eggs, I still think it is highly suspicious that the failures have happened since that underneath structure went in. Could a bird expert learn anything from the fragments about that?

Of course, I agree they shouldn't be retrieved early. Sure wish there were a camera up there so we could see if the eggs actually hatched, that would be a clue.

Karen Anne Kolling

Another letter:

Hi Marie,

Thanks for all of your web updates concerning the hawks. I'm happy to see that the times reported on this. I'm also very happy to see that you (and others) are planning on examining the nest/eggs when PM and Lola decide to abandon the nest. I find this particularly necessary since nobody examined the nest last year (as far as I know).

Aimee Van Dyne

And another:

Hi Marie,

What about pollution/toxic accumulation as being a problem with fertility?

Waiting with much anticipation and anxiety,

amy campbell

John Blakeman, in regard to testing the eggs for pesticides, expresses a diffent opinion about when to retrieve the eggs:


I saw the posting suggesting the retrieval of an egg for pesticide analysis. If it were done, I'm absolutely certain nothing untoward would be discovered. First, red-tails never were affected by DDT. Their prey, in this case, squirrels, rats, and pigeons, just don't accumulate pesticides. Yes, a stray rat may have some powerful rodenticide that
could affect the hawk, but the affect would be death, not a contaminated egg. And Junior and Charlotte on the South are eating the same foods.

On the other hand, don't be concerned about any disruption of the pair by someone entering the nest. If red-tail pairs could be disrupted by someone entering their nest spaces, the species would be in trouble. In rural areas, farm machinery, cattle, and just plain hikers commonly move right up beneath a nest tree and almost always drive off the sitting adult. We are talking here of nests just 50 ft above the humans on the
ground, not a nest 12 stories (sp?) high. The birds always -- always -- return and resume their normal activities.

I've been involved in any number of incursions into active red-tail nests, and it's always a spectacle. As the nest is approached while climbing the tree, or while exposing ones self at a nearby elevated observation blind, the birds begin to scream loudly. As the nest is approached, they begin to make awesome diving plunges at the climber. When we reach into the nest to temporarily take out the eyasses for examination and banding, the adults become even more incensed. They dive at us with talons outstretched as they shoot past our heads just a few feet away.

But they seldom actually contact the intruding researchers (except in California, where the red-tail population is noted for attacking nest intruders -- out there, the researcher is wise to wear a leather, talon-proof jacket, and a helmet, preferably with two big eyes painted on the back of it to help divert the hawks' attacks).

In all cases, the hawks quickly return to their normal activities once we leave the nest and the nest tree. This apparently disruptive episode doesn't threaten the pair bond, fidelity to the nest or territory, or result in any other untoward happenstance. If anything, an infrequent "nest raiding" experience actually strengthens the pair in their
cooperative defense of the nest.

Red-tails commonly encounter and know instinctively how to react to nest incursions. It's not overly disruptive. They can withstand such an event perfectly. There is no harm done, if conducted by someone with knowledge and experience.

Throwing a saddle on a colt for the first time is probably more disruptive.

Now, back to your more important point, the presence of the steel at the bottom of the nest. Could this be conducting away sufficient heat to preclude successful incubation? Perhaps. The nest is already very shallow, a result of the "supporting" spikes, which trick the adults into believing that the shallow nest they have constructed is sufficiently firm. Without the prongs, a large pile of loose sticks must be assembled to create the feeling of a firm nest.

But if the steel bottom of the present new structure were conducting heat away from incubation, we shouldn't have seen the birds standing up and looking down into the nest. Because the eggs would have been dead early on, they would have remained in the nest and incubation would have gone on without disruption or change, for probably six or seven weeks. With dead or infertile eggs, the birds just sit, interminably, until they give up as hormone prompts tell them to start doing other things in their daily lives.

But am I correct in understanding that the adults stood around the 927 nest and looked down into it, as though new eyasses (or a broken egg) had appeared? If so, that's evidence that an egg had developed and something hatched or fell out of an egg.

I don't feel that the metal bottom could have cooled the eggs. The sitting female would have discerned the coolness in the nest and would have continued to tuck in new lining until everything felt warm enough for her babies. That's a crucial element in successful nesting. It would have been attended to by this older female.


John A. Blakeman

A new angle is brought up in the following letter:

Dear Marie,
Like so many others who love them, I have been spending the last week processing my disappointment over Pale Male and Lola's egg not hatching.
Someone I work with told me that other species of birds roll unhatched eggs out of the nest. I was hoping that you or John Blakeman could tell me what happens to the unhatched hawk eggs.
Thanking you for any information you can provide.
Joan Corr

Now Donna Browne adds a comment based on her experience with doves:

Hi Marie,
Remember in past seasons how it was said that the reason the Central Park South Hawk's nest had failed was because the eggs had rolled out of the nest?
Then you posted an email from John Blakeman who said no self respecting Red-tail would allow their eggs to just roll off. There was talk about the high winds up there on the corbel and the possibility that perhaps the corbel was slanted just a little for drainage.
I wondered at the time if Charlotte, as do the female doves I have at home who are mateless and therefore lay infertile eggs, had rolled the nonviable eggs out of the nest herself. Knowing eventually, in some way, that they were duds and therefore clearing the decks for a second clutch. But that brought up the question as to why in failed years the Fifth Avenue hawks had not done the same. Did Charlotte know something that Pale Male's mates didn't? Is there a difference in the nests or location that allows the procedure in one but not the other? Is Charlotte "wired" as are my doves for this behavior but then why aren't the other RT females in the park?

The Seven Pleasures of Birding

Early Birders [Chris Cooper among them]at the Point, 4/12/06
Photo: M. Winn

On our early morning walk the other day we enjoyed the company of one of the park's best birders, Chris Cooper, At some point Chris referred to a list he had written that summed up the joys of birdwatching. Intrigued, I asked if he'd forward it and he obliged. I think you'll agree that he is, [to use his own words--see below,] "a language-gifted primate" par excellence.

Hi, Marie,

As promised, here are the Seven Pleasures of Birding, at least as I've determined them:

1. The beauty of the birds
2. The beauty of being in a natural setting
3. The joys of hunting, without the bloodshed
4. The joy of collecting (in that the practice of keeping lists -- life lists, day lists, etc.-- appeals to the same impulse as, say, stamp collecting)
5. The joy of puzzle-solving (in making those tough identifications)
6. The pleasure of scientific discovery (new observations about behavior, etc.)

and saving the best for last,

7. The Unicorn Effect--After you've been birding for even a little while, there are birds you've heard of or seen in books that capture your imagination, but you've never seen for yourself...and then one day, there it is in front of you, as if some mythical creature has stepped out of a storybook and come to life. There's no thrill quite like it.

If you get tired of people asking you, "Why do you go birdwatching?" as I eventually did, these are handy to whip out.

Note that what's NOT on my list as one of the pleasures of birding is the social factor, simply because some folks get a kick out of socializing while birding, some folks get juiced by the solitary experience, and some of us enjoy either.

Also note that the Seven Pleasures of Birding--what makes the activity *enjoyable*--should not be confused with what makes the activity *accessible*, though obviously the two are related. Why birding, and not "mammaling" or somesuch? Why do we language-gifted primates so easily become obsessed with chasing after feathered dinosaurs? Put like that, it hardly seems like a natural fit, but there are several factors involved of which we're both well aware--

--Most birds are diurnal, like us, while many of our closer mammalian kin are nocturnal; so birds are more readily observable. Yet unlike other diurnal creatures that are also observable--the many diurnal insects, for example--birds are warm-blooded vertebrates like us, who defend territories and care for young much as we do; so we can empathize with them.

--Partly because of this diurnal/nocturnal difference, birds communicate through the same primary senses, sight and sound, as we do, so we can easily appreciate their stunning visuals and beautiful songs. (Compare that to other mammals, whose primary sense is often scent, which can be much more useful in the dark.)

--Birds can fly! That mobility, unparalleled by any other group of living things, gives them access to the entire planet and virtually all of its varied habitats--so you can go birding anywhere, and you're likely to find a wide variety of species (compared to mammals) to delight you wherever you do. But I think more significant is that birds' ability to fly captures our imagination; it's the ultimate expression of freedom, and it touches some deep chord in the human spirit.

Obviously, I've spent WAY too much time thinking about this. And I'm rambling.


After reading this I wrote Chris and asked: What about bats? He answered:

As for bats: they're second-rate flyers, in my humble opinion. Flight has evolved a number of times on our planet, but never as near perfectly as in the birds--which is no doubt why they fill the vast majority of ecological niches available to flying megafauna, and goes a long way to explaining why they're the only dinosaurs that survived the mass extinction at the end of the Cretaceous. (That matchless mobility again: In a time of environmental upheaval, they could travel to safe havens, and then when conditions improved, these travelers would be among the first to re-colonize depopulated habitats. This is all supposition, of course.)

And besides, bats are nocturnal, so all the reasons I listed why nocturnal animals are unlikely to grab human attention still apply. Instead of capturing our imagination and inspiring our spirit, their nocturnal flying (and their unusual appearance, a consequence of their nocturnal adaptations) has the opposite effect: It freaks us out.

Give bats their due, though; if I remember correctly, they're one of the most diverse groups of mammals (in terms of number of different species), so they must be doing something right. Why birds haven't completely displaced them from all niches is something of a mystery to me; bats must have some advantage (echolocation? a superior sense of smell?) that compensates for their inferior flight characteristics.

Sunday, April 23, 2006

Coming soon:

A compendium of readers' questions and speculation about Pale Male & Lola's nest failure, as well as John Blakeman's comments in response.

Concern about the Trump-Parc nest

Charlotte on nest yesterday- 4/22/06
Photo by Bruce Yolton

Bruce Yolton, one of the key hawkwatchers of the Trump-Parc pair -- --- writes:

Doing The Math On Central Park South

Doing the math, I'm concerned about the Trump Parc nest. Given when the first egg was discovered and padding very generously for delayed incubation and hatching this is the time line:

March 13, First egg discovered
March 15, Possible delay of incubation, 2 days
April 19, Incubation, 28-35 Days
April 23, Hatching, up to 4 days

I think we should prepare ourselves for a negative outcome with this first set of eggs.

PS from Marie: If I understand Bruce's timeline correctly, he is saying that the eggs should have hatched by April 19th, the 35th day after the egg was laid, based on the March 13th egg laying date.[That date is definite. Unlike at the Fifth Ave. nest, we can see into this nest from certain vantage points.] Therefore on April 23, today, the hatch is 4 days late. This is sort of like having a woman be 10 months pregnant. It doesn't happen.