Monday, September 19, 2005

A new Q&A with an old friend: John Blakeman

A question from regular website correspondent Mai Stewart and an answer from John Blakeman. [Note: Both Q. and A have been abbreviated.]

Hi John,

I recall that one of your comments/warnings was that in order to survive their first year, the babies, even tho successfully fledged, needed to be able to learn to hunt for + feed themselves -- and that this is the most common reason for the lack of survival of fledglings in the wild .

Do you think it's too soon to tell whether these hawks have actually mastered the skills needed to support themselves, and survive? Do you think we need more evidence, or more time, to really tell the story? (Of course, assuming they do survive, an equally, if not more interesting story, will be what happens re territories -- That remains to be seen!)
I'd be interested in any thoughts/ideas you would have.

Thank you,
Mai Stewart
Yes, early in the summer I was very concerned that the new fledglings from the Trump Parc nest would have great difficulties learning how to successfully and consistently capture food. The Central Park pigeons seemed completely out of the equation, as they can fly so much faster then the red-tails, and the ability of the adults to capture these abundant birds depends, I think, almost solely on clever stealth in the form of a partially concealed ambush, either while pigeons are feeding and not paying attention, or by plunging into trees where perched pigeons think they are safe. I have no doubt that both such pigeon-catching strategies require a lot of experience and mature athletic prowess. Hawks in their first summer have neither, so pigeons haven't been much a part of their apparent success (except for those provided by the parents).
Likewise, I initially thought that rats wouldn't be so commonly available to the hawks, either, as these rodents are primarily nocturnal, and hawks can't see any better at night than we can. But it appears that a good number of rats are available during the daylight hours in Central Park, and rats are actually perfect prey upon which inexperienced youngsters can learn the strategies and mechanics of consistent success Rats are nearsighted, so they don't see an approaching hawk, and they don't run very fast, compared to the diving flight speeds of our big red-tails. They are easily killed by the hawk's talons, and lastly, they provide very ample and nutritious food. I think rats are better prey than the common voles that rural red-tails subside on. One or two rats a day is ample sustenance. The smaller, gerbil-sized voles must be eaten in daily quantities of four or five.
In short, I'm now convinced that Central Park rats are abundant, and for whatever reason related to Central Park, sufficient numbers are out wandering around in the daylight for the red-tails to thrive, especially the birds of the year trying to learn how to hunt and kill.
Several times I've gone back and pondered Lincoln Karim's many summer photos of the Trump Parc fledglings. When perched, almost every single image of these birds shows that they have an enlarged, full crop. These birds are eating well, which may also contribute to their disregard of nearby humans. Frankly, life has been extremely good for this year's eyasses. I have no doubt now that they have successfully learned how to hunt and kill in Central Park.
With their full crops, they are probably so fully sated that their migratory urges are suppressed. Right now, in mid September, is when immatures begin to really feel the urge to begin to drift and migrate southward. Here in rural Ohio, virtually all of our summer-resident fledglings have left (or have been forced out of) their natal territories. A few red-tails are being seen at migration spotting areas, especially to the north. The migration so far is more of a general southward population drift of immatures. With the right weather patterns, this will break out into a well-formed mass migration at places like Hawk Mountain in Pennsylvania and at Cape May in New Jersey. Red-tails are already starting to drift across the western shores of Lake Erie, dropping down from Michigan and Ontario.
A large percentage of the red-tails hatched last spring are already dead, having starved from a lack of food. Out here in rural areas, there are lots of voles, but they are widely scattered. Successful hunting of them demands a lot of a young, inexperienced hawk. Many met their nutritional demise in August. The birds that survive into September have a much greater chance of migrating, surviving the winter at some more southern latitude, and then making their way back to the north next spring. Many will still expire this winter, but it appears that the vast majority that die do so in August from lack of food.
But there is apparently no lack of food in Central Park. The immatures there are fat and sassy, utterly disregarding those thousands of biped animals that their rural cousins are so wary of.
In summary, the young Central Park red-tails have passed the greatest period of vulnerability with great success. Let's see if they elect to stay in Manhattan, or will they drift off toward New Jersey. I hope we can continue to follow their lives.
Keep me posted.

John A. Blakeman