Marie Winn's Central Park Nature News: 2006-05-28

Saturday, June 03, 2006

Last two comments from Chris Lyons

Hawkeye and Rose, the Fordham pair [ before their 3 chicks hatched]
Photo by Rich Fleisher

Some very astute [and amusing] comments on the various ideas we've been debating as well as some thoughts about Buteo jamaicensis in general from Chris Lyons:

Blakeman confirmed a suspicion I've long had--that one reason Red-Tails keep confounding the experts is that the experts don't know nearly enough about Red-Tails. There's far less research done on this species than many other raptors, because it hasn't been endangered or threatened in quite some time. And of course, the non urban-nesting Red-Tails are still shy of humans, and particularly try to avoid putting their nests where they can be easily observed. So we simply don't know how common or rare orangey chested eyasses are. And this species is so variable in its plumage across
its enormous range that learning they don't have orangey chests in states as far away as Ohio or Colorado doesn't really mean anything.

My theory is that a specific race of the Eastern Red-Tailed Hawk has been more likely to colonize urban areas. Pale Male is part of that race. Maybe if this could be confirmed, it could be named after him? Buteo jamaicensis palemaleus? Maybe somebody who knows more Latin should take a crack at it.

In addition:

There could definitely be many nestlings that don't get this coloration. This is a species that can very widely in appearance--there are all-white Red-Tails
that make Pale Male look swarthy by comparison.

I think before we make any assumptions about which eyass plumage is 'normal', a lot more data is required, from a variety of sources.

It's a real mystery--and right now, I just don't see an answer, except that the very species itself is undergoing significant and rapid change across its
entire range, in response to major environmental changes over the past several decades--Red-Tails are increasing in places where they were formerly unknown, and diminishing in areas where they were once common. And our attention to this species has likewise undergone substantial change. It's not just that we aren't shooting at them--we're positively DOTING on them, these birds that were seen as rapacious killers
and vermin a few generations ago. People feel so distanced from nature now that when they see a hawk, a living symbol of freedom and ferocity, living and raising families among them, it makes them feel like some kind of link to the past has been reestablished. And because of this fascination, we're noticing many things about these birds we never noticed before, and
we're able to share observations and images faster than ever before. And the birds have learned to tolerate our close observation, as never before.

I remain skeptical that Pale Male has had a significant impact on the genetics and behavior of his species. But he's definitely had a major impact on our behavior. As for genetics, do you know of any married couples with children who met at the boat pond?

Blakeman recants

Mom of Cathedral nest on Angel Gabriel's trumpet [missing its bell]
Photo by Donna Browne, taken just before storm, 6/1/06
http://palemaleirregulars.blogspot.com/

This might [or might not] be the final salvo in the Orange Chests skirmish:

Marie,

I don't want to prolong the banter on the putative proliferation of Pale Male's genes. As all of us have indicated, we are all guessing.

And my guesses I think, now, are wrong. A good red-tail-studying friend of mine called me and said that he has an orange-breasted eyass about ready to fledge from a typical Ohio nest. No pigeons or rats out here.

Others, as you have noted, have claimed wide distribution of this color trait.

Therefore, I recant my suggestions that orange breasts in red-tail eyasses can be caused by the unique food in urban environments. Although I don't recall seeing one of these here in northern Ohio, others have. My suggested explanation is not supported by real data.

The matter is closed. Although uncommon here, the orange-breasted trait is apparently widely distributed elsewhere. Therefore it can't be used as evidence for or against Pale Male's local origin of it, or it's indication of any Pale Male ancestry.

Such is the conduct of evidence-based science.

A related note (perhaps posted tangentially in one of my previous letters -- I've mentioned this somewhere before). The red-tails here in the counties of northern Ohio between Sandusky and Toledo, along the SW coast of Lake Erie, are commonly colored very much like those in the American West. Many of the local birds, including Savanna II, my falconry red-tail, have breasts that are decidedly light brown or gold-tinged, instead of the more typical white tint. I've had falconers look at my bird and wonder why I have a Western subspecies, Buteo jamaicensis calurus, here in Ohio, where the subspecies is the same as in New York, B. j. borealis.

This is a case where a local population has a distinctive, separate plumage coloration. My local birds are only colored like B. j. calurus, specimens. Western red-tails are notably smaller than our eastern birds. My bird is big, as are all the other dark-colored ones. It's a true B. j. borealis. She's just colored like a Western red-tail.

So that should settle the matter. Plumage color isn't going to be much help in determining red-tail genealogies. My contributions haven't been particularly helpful other than to throw out the entire topic. I appreciate the useful contributions of others.

It's back to getting some DNA samples, or getting eyasses color-banded, tasks probably even more difficult than trying to parse ancestry by feather color.

Sincerely,

John A. Blakeman

PS from Marie : The headline of this posting was provided by John Blakeman, not by me. Didn't want you to think I was being mean-spirited!

Friday, June 02, 2006

Re-posting letters from John Blakeman and Chris Lyons

Many readers have written in about problems getting this posting [below] on the website today. I've removed all formatting on the posts, eliminated the photos, and am posting these extremely interesting texts again. Hope this works.

Two fascinating letters below, one by John Blakeman, the other by Chris Lyons, a new website correspondent whose reports on the redtail family at Fordham University often appear on The City Birder, Rob Jett's website about Prospect Park.

Marie,
For those searching for some good, not very mathematical reason to discount the monstrous geometric progressions indicating that Pale Male might now have offspring numbering in multiple digits, naysayers can ask if Pale Male was the only red-tail siring offspring. Obviously, there were tens of thousands of other breeding males who also produced ample offspring in the last decade or so. If all of them had the breeding successes of Pale Male, the entire surface of the world would be covered with them (or something). More seriously, if Pale Male's progeny proliferated in any way, what might have been their selective advantages? What might it have been about Pale Male's offspring that could have caused them to succeed in any way better than those of other males? Having a colorful, even orange-ish breast conveys no advantages I can think of.

Personally, I think red-tail eyasses fledged in Central Park probably have some significant disadvantages against their rural-hatched brethren. When Central Park yearlings leave NYC in their end-of-summer migrations, they necessarily must make their livelihoods out in wild, rural areas -- where they have no real experience or understanding of the non-urban threats and challenges there.

A young Ohio actress who goes to New York City to enter the theater business has to learn a lot of things quite foreign to her childhood in a small Ohio town. Conversely, a New York red-tail trying to survive its first winter in some wild, rural area somewhere in a Southern state will have equal challenges. Knowing red-tails as I do, I really think a Central Park immature red-tail has things really stacked against her. She's never even seen a vole, let alone learned where to hunt for one. (Voles are the sustenance food of rural red-tails.) Rural pigeons are virtually impossible to catch, as they don't sit around in large flocks eating provided grain. There are rats in the countryside, but they have the good sense not to wonder out in the daylight. In short, urban red-tails trying to make it through their first year in the rural wild have multiple disadvantages that their rural-hatched relatives don't. The rural birds learned out to survive out there in June and July while still being tended to by their parents. Central Park yearlings learned how to live in Central Park, and that's very different from being able to capture sufficient prey on in the wild in the cold winter.

In short, I honestly doubt that many of Pale Male's offspring have gone on to breed. Certainly no inordinately large class of them have. The realities of first year survival in rural and wild environments must be a part of any long term survival equation. The multiplication key on the calculator isn't the only one that must be punched. The division and subtraction keys are also very prominent in calculating the probabilities of survival. Again, I don't think NYC-hatched red-tails have anything going for them when they get out into the rural wild. It's a tough world out there.

--John Blakeman

Christopher Lyons adds:

Could I just add a quibble I haven't seen yet?

Obviously it's fun to speculate about the maximum number of descendents Pale Male could have, even though we know it's wildly out of touch with reality. But it's ignoring the fact that these theoretical
hawks are not just Pale Male's descendents.

Every single eyass that fledged from 927 Fifth Ave was only 50% Pale Male.

While some inbreeding may occur in this species, as John Blakeman has said, we can assume that most of his kids hooked up with unrelated Red-Tails, either by leaving the immediate area, or finding a territory
nearby, and attracting a mate from Red-Tails being born in nearby areas, or coming from up north to spend the winter, or passing through in migration.

So by and large, Pale Male only provided 25% of the genes for his grandkids.

And with each passing generation, his genes are diluted. By the time you got to tens of thousands of descendents, you'd be talking about hawks who were maybe 1% Pale Male--and 99% other birds. And in the evolutionary sweepstakes, that's a win--you win if your genes survive. Better to have a lot of descendents who are a LITTLE bit you than a few who have a larger dose of your genes. The phrase about not putting all your eggs in one basket comes to mind, but that's probably inappropriate in this context.

The entire North American Red-Tail population has been estimated at 300,000 individuals, by the way--which may be low. But whatever the number is, it's unlikely to have gotten much larger since Pale Male was hatched. So a lot of other Red-Tails were propagating their genes as well.

We don't have enough data on this species to say with authority that Pale Male has had an amazingly high number of offspring--above average, certainly, particularly when compared to Red-Tails living in more wild settings. But with Red-Tails breeding in so many urban and suburban areas across North America, it may well be that many other Red-Tails have had equal or higher breeding success rates. They just didn't have such a visible piece of real estate, with so many ardent observers present.

One study I just read a summary of estimated that out of 1,000 Red-Tail eggs laid in one breeding season, there might be as few as 40 living Red-Tails ten years later. And it's entirely possible that's an
overestimation.

It's possible Pale Male's young have a higher survival rate--but so would all the other hawks colonizing urban and suburban areas with higher prey densities. These hawks have genetic agendas of their own, and would be competing with Pale Male's descendents for
territories and mates, often successfully. And judging from the photographic evidence I'm seeing, probably a lot of them have orangey-chested eyasses, and would have had even if Pale Male had never bred.

Btw, this morning I took a look at "Raptors of the World", by James Ferguson-Lees and David A. Christie. The color plate in that book that covers Red-Tailed Hawks was done by Kim Franklin--who is a guy (the book is British in origin, though published here by Houghton Mifflin) There is one illustration of a juvenile Red-Tail. And that bird has definite orangey color on the breast, though it's starting to fade.

Annoyingly, the text in the book doesn't go into detail about the plumage changes of developing eyasses. They clearly had no idea what a matter of vital significance this would become. ;)

Orange-chested nestlings: Is it the diet? Chris Lyons investigates

Orange-chested chicks at Cathedral of St. John the Divine
Photo by Bruce Yolton http://urbanhawks.blogs.com/

Chris Lyons, a careful observer of the Fordham redtail family [Hawkeye and Rose and three kids], has been looking into the orange chest mystery. Specifically, he's been researching the notion, promulgated by John Blakeman in a recent posting, that the orange chest is a result of diet, not genetics. Since two chicks of a previous Bronx nesting [on a fire escape!] ended up at a wildlife rehabilitation Center near Brewster, New York, Chris contacted Paul Kupchok, the director of that center, to ask about the diet of those chicks. Here are Chris's findings:

I explained to Mr. Kupchok about the two chicks from
the 2004 fire escape nest in The Bronx, that I believe to be Hawkeye and Rose's progeny, and he remembered them well. Both were successfully reared to young adulthood, and released in August of that year, not far from the center. As he recalled, both of them did develop the orangey chest color--he wasn't 100% certain, but he said there would be photographs of them at different stages of growth, if it had to be confirmed. He was pretty sure they did develop that color.

Mr. Kupchok said he never feeds pigeons to the raptors in his care. He was quite emphatic on this point. They mainly get field mice (live ones, in the latter stages, when they're learning to hunt). He said that aside from the fact that he has special feelings for birds that make it impossible for him to sacrifice the lives of pigeons to feed hawks, he also thinks it's very dangerous to most raptors to feed them Rock Pigeons, because of the diseases this species can carry. He says maybe urban hawks have developed resistance, but a pigeon diet could be deadly for those that haven't. For this reason, he probably wouldn't be feeding them city rats either (and they'd be kind of hard to obtain where he is, anyway). I'm not quite clear on whether the diet would be 100% field mice, but that was the impression I got.

Mr. Kupchok has been rearing young Red-Tails and rehabilitating injured ones for about 20 years now. He says that during that time, he has seen many Red-Tail eyasses, from all parts of New York State, some from well north of where he is, and that many developed the orangey chest color, and many others did not. It seems to be a very common genetic trait, but not a universal one. He was sure he'd seen eyasses from before Pale Male's time that had that coloration--and in any event, very few of the birds he raised were from New York City (probably just the two from The Bronx, but I forgot to ask). He certainly was open to the possibility that it was a common trait among New York City Red-Tail chicks because of Pale Male's genes, but of course it could just as easily be possibility that Red-Tails with the tendency to produce orangey-chested eyasses are more likely to exhibit this type of nesting behavior, but damned if I can see how you'd go about proving that.

All this new information by no means disproves the theory that Pale Male's genes are widespread among the local Red-Tail population (I think it would be odd if this were not the case), but the orangey chests basically don't prove much of anything. It just so happens that the Red-Tail eyasses that John Blakeman and Len Soucy have seen did not have this coloration. It's not an uncommon trait at all.

I personally believe that the colonization of New York City by Red-Tails was a gradual process, that involved many different birds, coming from New Jersey, Westchester, and Long Island, and probably some from further afield--but I still believe Pale Male is an important contributor to the local gene pool. Possibly not a predominant one, though. And there is no reason at all to think his genes are predominant outside the immediate area. When we see Red-Tail eyasses with orangey chests around Connecticut courthouses, or Boston college campuses, there is no reason to assume they have anything to do with Pale Male. It's possible, but not much more likely than that he's related to the orangey chested eyasses that Anthony Galvan III photographed in California last year.

We just don't know enough about this species, and its incredibly wide distribution and genetic diversity, combined with its great variability in plumage, make it dangerous to overgeneralize on the basis of physical appearance. There's still disagreement on the subject of whether the Harlan's Hawk is a separate species closely related to Red-Tails, or simply a Red-Tail subspecies with a distinctive appearance (the former view is currently prevalent among ornithologists). Even when careful DNA testing is done, there are questions that still resist definitive answers.

And the field mice diet the transplanted Bronx chicks got from very early in life tends to rule out the theory that the coloration comes from eating city birds and/or rats. As well as the fact that Mr. Kupchok has seen so many eyasses with this chest coloration from all over New York State, for the better part of 20 years.

So basically, we know nothing.

Raccoon pix

Raccoon Mom trying to keep baby safe in the nest
Photo by Eleasnor Tauber

Thursday, June 01, 2006

Blakeman : it's a tough world out there for urban hawks *******Chris Lyons: What about Mrs. Pale's genes?

As I was going to St Ives: How many kids could Pale Male have?

Pale Male with twig, the Carlyle hotel in backiground
Photo by Lincoln Karim - May 31, 2006

Steve Watson, our California friend via Kestrel Cam , lent his agile brain to my Hawk Progeny challenge which was, more or less:

Given the number of successful offspring that came out of the Fifth Avenue nest from 1995 to 2004, and supposing that all offspring, and offspring of offspring were to survive [I KNOW that's impossible, as Blakeman points out in a recent note--but that's the way the challenge goes] how many hawks could there now be in the world with Pale Male's genes?

In the wee hours of the morning [a fellow insomniac or is it just California time?] Watson did the following calculations:

I'll take a shot at it...it's late at night and I reserve the right to say "ooooppps...THAT was a dumb mistake", but here goes...

Using the numbers posted for Pale Male's offspring for each year (prolific fella that he is), apply the following assumptions:

1) Each set of PM's offsprings heads off into the wild to mate
2) All offspring survive
3) All offspring mate
4) No consanguinuity of any generations or offspring (all offspring in any generation find a non-PM descendant to mate with)
5) Each pairing results in 3 eyasses
6) All eyasses of each pairing survive
7) Each pair mates once and then never again (this avoids having to sum over generations)

For 1995 (3 offspring) you get the following geometric progression
3, 9, 27, 81, 243...etc., until in 2006 you have 531441 in generation 12 (3 to the 12th power).

To generalize, let n_i be the number of offspring of PM in year i, i = 0..11 (that is, 1995 to 2006).
The total potential offspring in year 11 is (and this is hard to write without using real mathematical symbols):

Sum_i=0,11 ((n_i * 3)*3^(11-i))

which yields 792,477 potential offspring. This is ridiculous, of course, so you'd have start applying real assumptions, such as probabilities of pairing, probabilities for clutch size, etc. Oh, and pairs don't just breed once and then die or stop breeding. And so on.

Anyway, I'm now reminded of why compound interest is such a good thing, and that I need to go make an appointment with my stockbroker to re-evaluate my retirement funds! :) The number 3^n gets big FAST as n grows. It would be interesting to try this with empirical data...

PS from Marie

It's the following throwaway line in Watson's note that makes me think the number he came up with could be hugely, hugely bigger -- after all, think of how many years our pair -- Pale Male and his various mates --sent hawklets out into the world:

Oh, and pairs don't just breed once and then die or stop breeding.

Wednesday, May 31, 2006

It may not be the genes, says Blakeman

Trump-Parc nestlings getting ready to fledge
Photo by Lincoln Karim - 7/05

Marie,

Here's a rather disruptive -- but very plausible -- thought that came to mind as I further pondered the orange-breasted eyasses so frequently seen in urban areas in the East since Pale Male began his wonderful reign. There is the possibility that the orange or buff bright breast color of city eyasses might be an artifact of the peculiar food big city red-tails are now feeding their young. It may not be genetic at all.

We know that the yellowness of the skin of raptors derives from carotenoid chemicals in their food. Captive raptors seen at zoos commonly have rather dull skin coloration, compared to the bright yellow of wild raptors feeding on wild prey. My falconry red-tail "Savanna II" does not have the bright yellow feet and cere found on wild red-tails. She doesn't eat a diet of primarily wild-caught food. Could the orange breast color of eyasses be caused by some pigment or basal chemical found primarily in city pigeons or rats?

Rural red-tails almost never capture and consume pigeons, and Norway rats, too, are infrequently captured. These two species comprise the vast majority of the meals for the Central Park and other urban-nesting red-tails in New York City. You mentioned an orange-breasted red-tail eyass in the Boston area. We mustn't arbitrarily assign this trait to a pigmentation gene descended from Pale Male or any of his kindred. This feather color may be a result of the unique prey city hawks are capturing and feeding to their eyasses. If so, there may be far greater genetic diversity in the NYC red-tails -- and that would be better (no inbreeding problems in the future).

The red-tails seen in Central Park in recent years may not have descended from Pale Male at all. The unique breast color of the urban eyasses may just be a particular nutritional result of the city pigeons or rats they are fed. That would explain the infrequency (absence?) of orange breasted red-tails in wilder, rural populations. And it might also dethrone Pale Male as the putative patriarch of all of the current orange-breasted urban eyasses hither and yon. I do think, however, that the paleness of Pale Male's head is purely genetic. I've seen an exact match to Pale Male sitting on a fence post a mile from my rural home here in northern Ohio. Both of these birds have been eating very different prey. My rural pale male has been eating lots of voles. Pale Male has been eating rats and pigeons, so the color of the head feathers of these two birds does not result from their food.

--John Blakeman

Tuesday, May 30, 2006

Tracking down Pale Male's progeny

Trump-Parc nestlings, 2005
Photo by Lincoln Karim

Fifth Avenue nestlings, 2003
Photo by Lincoln Karim

Deborah Kops, a website reader, sent me the following link to a webcam of a Red-tailed hawk nest at MIT:

http://amps-tools.mit.edu/hawkcam/
When I looked at the images of the MIT chicks I was amazed to find that they had orange chests just like the Fifth Ave. and Trump Parc nestlings had. For the past year I've been corresponding with a number of hawk experts and hawk observers about the red chest phenomenon. Since John Blakeman and Len Soucy both asserted that in their experience this is not the usual nestling color, I began to wonder if it isn't a genetic marker of Pale Male's. It would suggest that all the red-chested nestlings around the city, at Fordham, in Prospect Park and perhaps even in Cambridge Massachusetts are relatives of Pale Male. It's an astonishing thought.

In a letter I sent to Deborah Kops I tried to figure out how many redtails there might be around who are part of the Pale Male Dynasty. Here is one of my calculations:
If you figure that the first Fifth Ave offspring were ready to breed in, say 1998, when there were 3-year-olds, and THEIR chicks were mature 2001, while the 1996 chicks were ready to breed in 1999, etc... you begin to have a geometrical progression. By 2006 there would be a huge number of relatives. Here's my first go at the math:

There were 3 chicks in '95, 3 in '96, 3 in '97, 3 in '98, 1 [survivor] inj '99, 3 in 2000, 3 in 2001, 0 survived in 2002, 2 in 2003. After that, 3 more in 2004 that might not be old enough to breed yet. My quick calculation, 9X3= 27, 27X4=81, 81X3 =246 etc. ends up with the figure of 59, 778 offspring by 2006. This can't be right! But in any event the number could be huge!

The bottom line is that nowadays urban redtails are far more common than they were ten or so years ago, hugely more common. Could they all be relatives of Pale Male's, a bird who may have been some sort of genetic abberation? If only we could do DNA analyses of some of these birds!

I sent these thoughts to John Blakeman, who pretty much rejected the idea--His letter is below. I've started a corresponence with Ron Austing, whose work I've admired for a long time. I'll let you know his response soon. I've also just received another letter from John Blakeman, in which he comes up with AN ENTIRELY DIFFERENT THEORY. I'll post that one tomorrow.

PS I'm excited about this. I feel we're at the beginning of an important quest.

PPS After Blakeman's letter I've added a comment. That's one of the perogatives of having my own website. I get the last word.

From John Blakeman:
Marie,

First, there really aren't many field biologists or ornithologists who would have data or wide experience with the orange-breasted eyasses on red-tail nests. That's because very few people actually study this otherwise common hawk on the nest. It requires that the scientist erect a closed study blind, get in there before sunrise, and just spent lots of hours observing -- when for the most part, nothing happens. When I was in college, my friend David Cornman and I were able to do a lot of this. David's Master's Thesis at Bowling Green State University described the eyass production of 66 Ohio red-tail nests. I saw a few of those with David, and I never recall seeing an orange-colored eyass.

The only other person I know who has done extensive field studies of red-tails on nests is Ron Austing, the author of a wonderful 1960s book, The World of the Red-tailed Hawk. Ron worked for years in an Ohio park district, bred red-tails (better than I did), and did extensive photography of them. You might pose the question of orange-breasted eyasses to him.

Now your math is correct. One or two Pale Male orange-breasted progeny could have sired thousands of new orange-breasted, blond-headed, building-nesting red-tails all over the East. But your ecology isn't correct. It just never works so simply or arithmetically. Only a minority of Pale Male eyasses ever reached adulthood. At best, it's 40 or 50 percent of those that fledge. Then, when adults, a number do not ever breed.

Here's the reason, and why I'm certain, that urban ledge-nesting red-tails are now so common, when formerly they were unheard of. I shared the AMNH expert's dismissal of Pale Male back in the early 90s. I, too, saw some reference to a putative red-tail nesting on the side of a Central Park building, and like everyone else who knows red-tails I was certain that some nice, well-meaning city people had simply misidentified the hawk. I, too, "knew" that it had to be a peregrine.

So why, then, are there now urban building-nesting red-tails across their Eastern range? Is it because this curious but successful trait originated with Pale Male and his successful progeny have taken these genes across the Eastern Seaboard? Or, might the phenomenon be something else?

It's something else. The biological complications of getting this trait so widely distributed in such a short period of time are too detailed to outline here. But reasons for the new building nesting trait in the East are simple and clear.

First, red-tails naturally do nest on ledges, in the West, where trees are scarce. I have delightfully watched ledge nests in northern Nevada, Wyoming, and Colorado. Red-tails are capable of very successfully creating and using nests on high, rock ledges. The buildings of NYC are for both red-tails and peregrines exact equivalents of tall cliffs. Therefore, the construction of urban ledge nests are clearly within the behavioral repertoire of this species.

But why, then, have urban red-tail ledge nests been seen only recently in the East, where preferred tree nest sites are common? I'm certain that this is the reason.

Until recently, red-tails were commonly shot and trapped. A few (unethical and illegal) "hunters" would shot hawks on site. After all, hawks ate rabbits, pheasants, and other desired game species. A dead hawk meant many live rabbits or pheasants (or so the thinking was).

Until recently, there was extensive trapping of fur bearers, and red-tails often got their legs crushed in these metal-leghold traps. In the 1970s I used to have 5 or more brought to me each year by the Ohio Division of Wildlife and citizens who came across the trapped hawks. All of them had to be dispatched, as a hawk with a missing foot hasn't a chance.

Lastly, many farmers used to have free-roaming (and unbelievably good tasting) poultry. The red-tail wasn't called by these people "chicken hawks" for nothing. Starving immatures in July and August, after the parents stopped feeding them, actually did kill chickens, the apologetics of Audubon and other conservation organizations notwithstanding.

But all of this hawk killing has come to a virtual end. The only hunters left are serious, committed, knowledgeable, and conservation minded devotees. The crass, "shoot it of it moves" types no longer bother. Today, they are at their computer games or otherwise occupied indoors. No one is trapping muskrats or minks anymore. And there no longer are many free-ranging poultry operations. Out in the countryside, things have changed dramatically in the last 20 years. It's not the 20th (or 19th) century anymore. Old stereotypes are simply gone. I live out here, and for 30 years taught the sons and daughters of these fine people. In regard to wildlife, things have changed dramatically.

Simply put, red-tailed hawks are no longer being killed by humans in any number. In the 19th and 20th centuries, a significant portion of fledged eyasses would be slain by the activities of people each year. No longer. Now, the red-tailed hawk population is free to expand without any significant or disruptive killing by humans.

The results are exactly what you have so wonderfully described and brought to our attention in New York City, the unprecedented colonization of the urban "cliffs" by this raptor who until now has stayed in the trees and edge forests of rural areas. The rural areas are now completely saturated with red-tails. There is no more space for rising eyasses. Formerly, lots of first-year red-tails were killed each year, along with a bunch of adults. This created lots of "holes" that survivors could fly in and fill.

Not today. Wild adults are now living into their teens, with never a bullet or lead shot passing by. The eyasses fledging off modern red-tail nests face formidable, and now natural, challenges in attaining adulthood and breeding. As I mentioned before, this is something Manhattan residents can understand. Getting a place to build a nest out in rural areas is now ever bit as hard as finding an affordable apartment in Manhattan. All the good red-tail territories are occupied by old, experienced adults. They will drive away any young interlopers. These old birds are in superb, "rent controlled" territories. They aren't going to be displaced.

Pale Male, a great patriarch, started the red-tail urbanization "movement." But I'm certain that it has continued in other venues by many other, non-related hawks. Remember, as I've always contended, everything must start with a copious and vulnerable food supply, and cities have this. The new urban red-tails have learned (I would have predicted that they couldn't or wouldn't have done this.) to capture city pigeons. And the rats are easy pickings.

So in the absence of any resident adults to drive them out, birds like Pale Male have been able to take up city residence and live comfortably, all because red-tails out in rural areas are no longer being killed in any number. A great conservation story this is.

As a red-tail biologist, I want to see how this begins to play out once urban environments become saturated with old, resident adults. It's very reasonable to believe that the birds at the Cathedral of St. John the Divine might be Pale Male progeny, having moved unchallenged just to the north. But what happens next, when all available urban territories are occupied. With two nests, I would presume that Central Park is already "filled up."

What happens next, when red-tails are everywhere in rural, suburban, and urban areas? It will be exciting to watch this play out over the next several years.

--John A,. Blakeman

Last word from Marie:
John shoots down my speculation about the number of PM offspring around by saying: " Only a minority of Pale Male eyasses ever reached adulthood. At best, it's 40 or 50 percent of those that fledge. Then, when adults, a number do not ever breed."

But even if it were only 25% of the offspring, and the offspring of offspring etc. , that could still be a sizable number of Pale Male relatives colonizing NYC and the northeast corridor. Twenty-five percent of 59, 778 redtails is 14, 868 redtails.

PS to readers: If anyone would like to have a go at calculating the number of offspring -- I'm pretty sure my number of 59,778 is not correct -- please send me your results.

It happened around sunset on Manhattanhenge evening

Sunset at the end of the canyon on Sunday night [5/28/06]

Photo: NY Times---The next one will be July 13th

Meanwhile, in Central Park...

Bob Levy, [crepuscular Central Park wanderer and Club George author] just sent in another narrative of special interest to the park's owl followers. It happened Sunday night too.

I normally would not give out the location of an owl but I think there is a good reason to do so this time. So many birders have been lamenting the disappearance of the gray morph Eastern Screech-Owl that had disappeared from the Point recently that I think it is important let them know that I think I might have found it. At about 8:15 pm I heard several birds excitedly calling from the farthest end of the north lobe on Central Park Lake near the area in which the Green Herons used to nest. (I emphasize the past tense, as the absence of a Green Heron nest this year is another disappointment to many). A female and male Northern Cardinal were part of this bird chorus. With their crests erect and bodies pulled up to make them look as large as possible, I recognized their body English was a defensive posture. Deeper inside and higher in the trees were at least four equally agitated American Robins. They moved around but not into a Weeping Willow Tree that appeared to contain whatever it was all the birds were expressing a strong objection to. At this point I experienced a delightful and unexpected diversion from my investigation. The cardinals quit their protest for a few moments. I followed them directly to a nest where I saw one nestling reach up to take food from its mother. She snuggled down inside the nest but the male went back to his position on the picket line. Then I turned my attention back toward the robins. I went to most northerly point on the path and looking south into the Weeping Willow. Behind the leaves I found the unmistakable outline of a small owl. Unfortunately the light was too dim and I was unable to determine if this was definitely an Eastern Screech-Owl much less a gray morph. It’s even possible it was another species but I have no proof to offer. At 8:28 pm the owl bolted from its perch with three yelling robins racing alongside it. Still hearing the male cardinal and the robins but unable to see them I tried to relocate the owl but I was unable to do so. I kept trying for another ten minutes but the calls of a Common Night Hawk distracted me. Following those calls I found two Common Night Hawks and a bat of unknown species (I freely confess I need some remedial batting instructions) scooping up flying insects above the Tupelo Meadow. Thinking I had a pretty good evening after finding the Northern Cardinal nest, possible Eastern Screech-Owl, Common Night Hawks and unidentified bat I had one more surprise coming. Near the stone steps leading out of the Ramble close to the weather forecasting equipment behind the Castle I found a mother raccoon and three cubs emerging from a tree cavity. That served as a perfect ending for my walk.

Monday, May 29, 2006

Blakeman on Pale Male genetics

One of the three orange-chested chicks at Cathedral of St. John the Divine
Photo by Bruce Yolton http://urbanhawks.blogs.com/ 5/26/06

Orange-chested nestlings at Fordham University [Bronx]
Photo by Rich Fleisher

http://www.fordham.edu/politicalsci/profs/fleisher/
richfleisher.html

Referring to my posting yesterday about the Cathedral nestlings and their possible relationship to Pale Male, John Blakeman writes:

Marie,

I concur with Len Soucy of the Raptor Trust. I, too, have never seen eyasses with the orange or buff (or whatever saturated color it is) breasts of the Manhattan red-tails.

This strongly suggests that all of these birds are closely related. Population biologists would prefer a wider genetic base, with parents and genotypes of diverse origins. But so far, there doesn't appear to have been any significant inbreeding problems. Three eyasses on a nest, as now at the St. John the Divine cathedral, is a sure sign of both behavioral and genetic success.

Raptor biologists should note (as I do) the apparent close relationship of all of the Manhattan red-tails. Instead of being colonized by separate and diverse invaders, it now appears that Manhattan has been colonized first by our man Pale Male and now his progeny. The genetic vitality of the population is maintained by the apparently unrelated females, who are drawn into new Manhattan territories, such as this one at the cathedral, by Pale Male offspring males who discover and take up new territories on the island.

There are a number of valuable lessons in red-tail colonization of new habitats here. This doesn't happen often. It should be closely studied and described. It would be ideal to get genetic characterizations of all of the resident red-tails, from which reliable genealogies could be determined. But that would, at the least, require the retrieval of newly-molted feathers from known parents, or more significantly, the adults should be trapped and blood samples taken. Out here in rural areas, we would do this in an instant, with no harm whatsoever to either the birds themselves, or to their continued presence in the territories. But simple and harmless trapping of red-tails in New York City just isn't going to happen, so speculation, based upon known raptor biology, will be the continuing explanation for what we see.

And what I want to see is the continued and successful residency of red-tails in New York City, on Manhattan Island in particular, without the appearance of any genetic inbreeding problems. So far, so good.

These birds continue to amaze, particularly as a population, not solely as individuals.

--John Blakeman

Sunday, May 28, 2006

Maybe the Ancient Greeks didn't know everything

Red-eared Sliders at the northern shore of Turtle Pond
Photo by Bob Levy

Here's a note I received from website correspondent Bob Levy, author of the recently published Club George: the Diary of a Central Park Bird-watcher [St. Martins Press] It's followed by my response and a related birdwatching tip:

Aeschylus and the inherent dangers of hatless bird-watching

I could not resist passing on this historical tidbit that struck me (the intended pun will quickly become apparent) as notable even if its veracity cannot be guaranteed 100%.

In Joe Queenan’s review of "The Book of Lost Books: An Incomplete History of All the Great Books You’ll Never Read," by Stuart Kelly, the reviewer repeats a cautionary tale from which certain members of the bird-watching community might benefit more than others. Queenan says that “Aeschylus, the father of Western drama, is said to have seen his career come to a premature end when an eagle mistook his inviting bald head for a rock and smashed a turtle against it.” (From the New York Times Book Review, Sunday April, 30, 2006, p. 12).

I certainly do not fault the eagle (species unspecified) for this accident that was an indisputably cruel fate for both playwright and turtle, but are there implications here for bird-watchers? While the odds of history repeating itself in this particular and peculiar way are unarguably slim, the story provides one more reason for many of us to include a hat among our bird-watching accessories. This might be most appropriate for visitors to Central Park’s Turtle Pond but hardhats might be overdoing it, don’t you think?

My response:

I read the review too, but wasn't kindly enough to see it as a cautionary tale for birdwatchers. I merely thought: Hmm, could someone in ancient Greece have mistaken a gull [a family known to drop clams etc. on hard surfaces to open them] for an eagle [a family not known for that kind of behavior]? I remember in my early hawkwatching days often mistaking gulls for hawks.

PS I once saw Peter Mott, former president of the New York City Audubon Society, give a useful lesson to a group of young birdwatchers at Central Park's Dana Center. He held his arms out to his sides, shoulder height, lowered his fingers at the wrists and said: "Gull." He repeated the action, but raised his fingers at the wrists and said: "Hawk."

I've been using this lesson [quietly of course] for years.

Marie Winn's Central Park Nature News