Friday, March 13, 2009

The Philadelphia Redtails

The Franklin Institute in Philadelphia

The nest box provided by the Franklin Institute for the nesting redtails

The news from website readers about the Philadelphia Redtails started trickling into my Inbox a few days ago, first from Mary Lenahan, a fourth grade teacher in the Philadelphia area, then from Linda Maslin, a regular website correspondent. Since I try to limit this page to subjects connected somehow to Central Park natural history, I did not intend to include the story of yet another pair of Red-tailed Hawks nesting on a big-city building. But I sent the news along to our old friend John Blakeman. And he responded, both to me and to someone at the Franklin Institute, the famous science museum the hawks have chosen for their nest. Since John Blakeman is, indeed, a subject clearly connected to Central Park natural history, I feel justified in welcoming the Philadelphia Redtails to this page. Here's a link to the first local news story about the nesting pair, from ABC News:

After you have read the article, and then John Blakeman's letter, you might want to visit Mary Lenahan's delightful Fourth Grade Blog at the end of this post. . By clicking on a photo there of one of the redtail pair, you can go to the webcam set up at the Franklin Institute nest.

Letter from John Blakeman:


Thanks so much for the Philadelphia link. I remember visiting The Franklin back in the early 90s, and just as with the Manhattan red-tails, central Philadelphia was no place for any self-respecting red-tail to nest---or so I would have (at the time, correctly) thought.
This pair, like so many others now, is replicating the colonization exploits begun by Pale Male himself, for almost surely the same reasons; there just aren't many un-occupied territories left out in more traditional rural and wild areas. It has nothing to do with suburban sprawl or human occupation of the countryside. Rather, it's that so few red-tails are being killed today. Their populations everywhere are at all-time highs.

Young pairs that want to nest are being forced into urban areas, and at the same time must learn new survival tricks that rural red-tails haven't been required to learn. My rural birds just never, ever bother trying to take a pigeon, unless it were injured by a car. The urban hawks are quickly learning the ways of city pigeons, rats, and squirrels. NYC red-tails are no longer the only Big City red-tails.

This is delightful, particularly because Philadelphians will be able to follow the reproductive exploits of this new pair. The nest-cams will present a continuing drama from which hawkwatchers everywhere can take delight. I'll be watching the pair.
And I hope someone records all of this. A continuous video record would allow for the most detailed analysis of every activity at the nest, incubation periods, defecation intervals, geographic orientation of the incubating birds, egg-rolling intervals and durations, food at the nest, food species analyses, etc. Unfortunately, to my knowledge, this information is not yet collected in any deliberate way for any of the NYC red-tail nests. This, at a science museum, is a prime opportunity. I hope arrangements are presently being made to graphically record all of this. There is an ornithological masters thesis here.
And a microphone would be fun, too. The sounds the parents and the eyasses make when being fed and incubated are different from any other. I wouldn't be surprised if the extensive library of avian sounds up at the Cornell ornithological lab lacks good nest recordings of the red-tail.

I commend the people who constructed the wooden nest rim support. It should work. It's almost identical to the one I constructed in my red-tail breeding trial way back in the early 70s here in Ohio.

I was glad to see that the female had dark brown irises, indicating that she's in at least her third year. At first, I was a bit concerned that this might be a very young pair, for which successful nesting so often fails. Still, this is most likely a first nesting attempt by the pair, and there is a good chance they will be unable to bring off eyasses this year. Everyone should understand that from the start. First nesting attempts by this species are often unsuccessful, but entirely normal and natural. Incubating eggs and feeding eyasses requires not only instinct but some experience, too. Any failure this year will set things up for future successes, as with the wild nests I study here in Ohio.

So I hope no one becomes distressed if eyasses fail to grace the skies around the The Franklin Institute this year. If they don't, be assured that the Institute has acted very properly in putting up the wooden nest rim, and the cameras will have no detrimental effects at all. This pair, like Pale Male and all the other NYC red-tails (unlike my wary rural hawks) are already adapted to nearby people, cars, noises, and all the other so-unnatural elements of urban life.
My best wishes to the Franklin pair. Ben, himself, would have uttered some wonderfully sage remark regarding this delightful happenstance.
--John Blakeman

Now here's the link to Mary Lenahan's blog: