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.