Answers About Raptors in New York, Part 3

Hawk Cam 2012

Chronicling the red-tailed hawks of Washington Square Park.

New York City Audubon’s director of conservation and science, Susan Elbin, has been responding to readers’ questions about hawks and other birds of prey in New York City. Following is her third and final set of responses, with additional answers provided by her colleague, John Rowden, the associate director of citizen science and outreach for New York City Audubon.

Thank you, readers, for your thoughtful questions and stay tuned to City Room for continuing coverage of Hawk Cam 2012.

Where is Pip?

— Posted by several readers

Several of you have asked this question. Last week, we ruled out the possibility that Pip is Bobby’s new mate, but we didn’t address the question of Pip’s whereabouts. The answer is: we don’t know, nor do we know if Pip is alive.

The last time Pip was seen, last August, she was a fledgling, having recently left the nest. It is important to keep in mind that the survival rate for the first year of life for hawks is low. In a Rochester, Alberta, study done by Stuart Luttich and others, survival of juveniles during that first year was less than 50 percent. But the survival rates are lower in urban areas, though we do not have statistics.

We do know a bit about red-tailed hawk dispersal from studies conducted in the Midwest. Juvenile red-tailed hawks tend to breed in the area in which they were raised (known as the natal area). So the chances are good that if Pip survived, she is living in New York City or nearby.

In order to know where she is, we need to be able to identify her in the wild, even after she assumes her adult plumage. She would need to have been banded or marked in a unique and obvious way. If we really wanted to know her movements, we would need to either have a team of observers looking for her and recording her locations, or attach a radio transmitter to her and track her.

New York City has a strong network of hawk watchers with high-powered telephoto lenses that enable them to identify individual adults, like Bobby or Pale Male, from far away. But it is mostly during the breeding season, when the pair is closely tied to the nesting site and has regular roosting or hunting areas, that we know where to look for these territorial hawks.

Please discuss the mating patterns of urban hawks, particularly after a male or female has lost its mate. Are these patterns different in rural areas?

— JLG, New York City

I have been following (in person, too) the lives of many of our red-tails this winter (if that is what we are finishing). Just like everyone else, I was amazed that the (at least) 2 dead or captured formels were replaced by new birds in only a few hours.

I am wondering whether this is common everywhere, or whether this is a unique situation. Although we know that there are quite a few younger unattached hawks around Manhattan, how is it possible that they learn of the “vacancy” within only a few hours.

— Jessica, New York

Jessica and JLG,

Your questions have to do with mating systems and mate choice: monogamy (one male, one female), polygyny (one male, many females), polyandry (one female, many males) and promiscuity (no real pair bonds).

Let’s look at monogamy, the most commonly occurring mating system in birds. Does the pair mate for one clutch, one year, or for life? If the pair mates for life and one of the pair dies, does the survivor mate again, and how quickly?

Red-tailed hawks are monogamous, and they usually maintain pair bonds until death of a partner. The acquisition of a new mate can happen quickly after the death of a member of the pair. This behavior is typical and occurs in rural as well as in urban hawks and has been documented since the 1930s — see “Bent’s Life Histories of North American Birds.”

We have seen this happen with Pale Male, the famous Fifth Avenue hawk, whose nesting behavior since 1990 has been keenly observed and well documented. He has had a series of mates, but only one at a time. He nested with each female until her death. We get to know these magnificent animals, and while it is easy to interpret their behavior by human standards, hawks behave like hawks and not like people. If another potential mate is nearby and available, courtship begins. The rapid acquisition of a new mate does not mean that the male was not waiting for his mate to return. It means that the resource was available, in this case, the new female, and the timing was right.

How many raptors are there total estimated to be breeding in the five boroughs? Which borough has the most? Now that Great Horned Owls are moving in, are they pushing out other raptors?

— Andre, New York

We are in the process of figuring out those numbers based on our own observations and from those in our network of volunteers.

You can help us find nests that we don’t yet know about by participating in the 2012 Raptor Nesting Survey. (The report from the last survey is here (pdf). If you see an active nest, you can also e-mail us at [email protected].

Do the hawks take turns sitting on the nest? I thought I saw the male come to the nest, the female leave and the male climb on the eggs. Also, does the female eat during her nest guarding? She seemed to ignore the rodent yesterday brought to the nest.

— annenewmanbacal

Good eyes! Yes, it’s true that both red-tailed hawk parents share the duties of incubation, although it’s not likely they share them equally. One study published by the Wisconsin Department of Natural Resources in 1979 found that the female incubated all night and much of the day, with the male giving her breaks in the morning and the afternoon.

It’s interesting that you also ask about food, because several studies, including this one by James W. Wiley in 1973 (pdf), have found that males provide most of the food that the female eats during incubation. Of course, the actual amount he provides may vary depending on the male’s hunting ability and how much prey is available in the area.

As to why the female didn’t seem to be eating the rat provided, it’s possible that what you saw that remained on the nest wasn’t the whole rat but perhaps the less desirable parts that hadn’t been discarded yet? I did see an image of a rat carcass on the nest that looked pretty eviscerated, so perhaps she had already eaten her fill of the good stuff and the rest was left over.

A red-tail hangs out every day in a tree at West 94th just inside the park. Other birders tell me his name is Holden. Who names these birds? We hope he starts a family. Does anyone know if Holden has a mate? Many thanks.

— Bill Ray

These birds come by their names in a variety of ways. Pale Male came by his because of the markedly pale plumage on his head, and was so named by Marie Winn, the author of “Red-Tails in Love,” who has chronicled his exploits.

Pip, the red-tailed fledgling of Washington Square, was named in a voting contest held by The New York Times shortly after she hatched. I would imagine that Holden came by his name by consensus among the birders in your area — perhaps they are fans of “Catcher in the Rye,” whose protagonist, Holden Caulfield, spends some time at the Central Park pond wondering where ducks go in winter.

But this brings up the interesting point of how we identify individual birds. Pale Male is a great example – he has very distinctive coloring that makes him easy to identify. In fact, red-tailed hawks are highly variable in plumage coloration across their North American range and are described as having a variety of “color morphs,” which means that there is color variation even though the birds belong to the same species. For further reading about variation in red-tailed hawks, I recommend picking up “Raptors of Western North America,” by Brian K. Wheeler (Princeton University Press, 2007).

Because there is so much variation in the species it can be relatively easy to tell individuals apart when you get a close look at their salient characteristics.

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