Wednesday, June 22, 2005

Questions about the Trump Parc nest & Blakeman's answers

THEY'RE HUGE!!



Photo by Lincoln Karim
June 21, 2005

Mai Stewart sent John Blakeman some questions and then e-mailed me his answers:

Question 1:
I've noticed how much higher above ground Jr.'s nest seems to be than PM's at 927 5th Avenue. Will this be dangerous for the baby hawks when they begin to fledge? If they have trouble on their first flights, could they possibly fall to the ground, a much longer way down than from 927, and could disaster ensue?

Or, on the other hand, might being so high be an advantage, since if they do have some difficulty flying initially, they'll have more height and space in which to recover and find their wings, so to speak?

Blakeman answers:
Your concerns about the height of the Trump Parc nest paralleled my original concerns about the height of the 927 nest. Both are way too high, compared to typical tree nests. But only because it takes so much energy to fly food and sticks way up there. For an eyass about to fledge, the height is a distinct advantage. When the birds take off for the first time, the just sort of set their wings and start flapping. Many of them just stagger clumsily to the ground when launched from low nests in smaller trees. The stratospheric elevations of the CP nests are an advantage, as the young birds will have a lot of soaring and flapping time before hitting the ground on their first flights. Not a problem, an advantage.

Question 2:
I've been amazed by the fact that the hawks eat feathers -- I didn't even think there was any nutritional value in feathers -- or are there bones in there, holding everything together? And I was really surprised to read in Donna Browne's notes that an eyass ate a pigeon foot "handily" -- I thought their feet were only something like cartilege -- is this nutritional?

Blakeman replies:
Yes, the birds eat feathers. But they provide no energy whatsoever. They go undigested and are coughed up in the following day's "casting" or pellet. The adults have learned that pigeons have a zillion feathers, and it can take all afternoon to sit up on a perch and try to pluck the feathers before offering naked tidbits of meat to the eyasses. The most efficient way to clean to food is to simply gobble down the beakfuls of feathers. That's what was seen. They only swallow the smaller body feathers. The flight feathers are too stiff and they are cast aside.

Question 3:
[This was missing from Mai's e-mail, but I've reconstructed the obvious question]: Can a parent redtail pick up a chick wandering too near to the edge of the nest and carry it back to a safer center area?

JB responds:
No, the parents have very little ability or prompts to pick up the wondering eyasses and scoot them back to the middle of the nest. They never, ever pick them, neither with their bills or feet. The parents seem rather oblivious to the impending loss of an eyass over the side.

After one goes down, the parents will often feed the little bird, prompted probably by its calls. But they don't take the eyass back to the nest, even though they are physically capable of that for the first 10 to 14 days or more.
One of the problems with carrying around a little eyass is that they are alive and they move. Hawks are predators, and they have an instantaneous, instinctive desire to squeeze anything that is both food and moves to death. Consequently, an eyass picked up by a parent would get pierced with several needle sharp talons if it ever made either a sound or flexed a muscle. Carrying around babies just isn't in the behavioral repertoire of hawks.

Question 4:
It is interesting to me to see the amount of time both parents spend on the nest w/ the chicks -- is this normal? Obviously, to me, as an emotional human, I find it very endearing that both parents are taking such an interest in their offspring -- or is it the novelty, this being their first experience with chicks?


Blakeman's answer:
About the long periods of time the parents spend at the nest with the eyasses: As they grow larger, this will become less frequent. They are standing around on the nest now to protect the eyasses, from weather and other predators. But when the little ones get bigger (and more aggressive to parents with food) the adults will spend more time off the nest. Later, in the week or two before fledging, the young will actually mob, even grab onto, the parents bringing food to the nest. That's when food will be dropped from above, to keep the tykes off the parent's backs. Finally, food will be dropped near the nest, or on an adjacent ledge, enticing the birds to fledge.