John Blakeman on the Hawk Capers of July 9th

John Blakeman sent me these fascinating comments on the eyass activities from last week captured by Carolyn Sutton in her terrific pictures:

"First, Carolyn's photos of the eyasses cavorting in the grass are really fine. They capture the social activities of these young birds---such as they are.

Readers and hawk watchers need to understand that these birds are in some minor mental conflict. The eyasses grew up together in the nest, fully accommodating each other, with virtually no social conflicts. Much of this good behavior on the nest was a result of the copious amounts of food the parents brought to their eyasses. At nests and territories with less ample food, the eyasses can get rather contentious about food brought to them when they are hungry.

That was one of the significant things I noted about the Franklin Institute nest, in contrast with the wild, rural nests I study in northern Ohio. Out here, in an utterly flat landscape dominated by hundreds of square miles of corn and soybean row-crops -- biological deserts void of any hawk prey -- our birds have to find the gerbil-like voles they prefer in roadside ditches and grassy or brushy field borders. Here in Ohio, it’s much tougher to bring food to eyasses on the nests. After a day of bad weather, our eyasses often go a day or more without food. When food is then brought to the nest, the eyasses lose self control and instantly grab out for the offered vole. Although the scene is not pleasant, the eyasses do restrain themselves sufficiently so as not to cause any injury to each other.

In fact, falconry has an ancient term to indicate that a pair of hawks have physically grabbed each other. They are said to have “crabbed.” Fortunately, there was no crabbing with Franklin Institute trio on the nest, and Carolyn’s photos show that even when the photographed pair found a mouse out in the grass, they did not physically contact each other. Both hawks were after the poor mouse, and one was able to snatch it up with its talons. The other bird, being a typical young red-tail entering its effective adolescence, could hardly restrain itself, almost—almost—crabbing with its sibling.

But like just like all human kids in Philadelphia (it would be hoped), these red-tails were well-raised and self-controlled. Contrast that, however, with golden eagles. These majestic raptors typically lay two eggs and two eaglets hatch. But only one ever fledges. Golden eagles are remarkable killers, with an innate instinct and desire to kill anything that moves, even on the nest. Raptor biologists call this the Cain and Able Effect. At some point before fledging, one of the eaglets reaches out and kills its sibling, even when parents have brought sufficient food to the nest. Fortunately, our red-tails are a bit more civil, and we didn’t have endure watching this sibling mortality, either in the nest itself, or when the birds were out in their first hunting exploits, as Carolyn’s photos reveal.

Then, you mentioned the mystical disappearance of the birds. Welcome to red-tail watching. This happens all the time. The birds are first seen prominently flying and perching in full view, often for much of the day. Then, they just disappear, evaporating into the cosmic ether. You can search every nook or cranny (well, every tree and phone pole), and the birds have just vanished. Where did they go? Hard to tell, but actually they just took an obscure, unrevealed perch somewhere. They probably spent the time preening, or just sat there looking out over the landscape from their hidden perch, taking in everything.

And again, how fine it would be to have a tiny radio transmitter on each of these eyasses, to learn exactly where they retreat to in these daily times of disappearance. There are still many red-tail mysteries to be solved. No one still knows exhaustively how these hawks spend their days.

You also raised the question about how far from the nest both the haggards and the eyasses might stray this summer. All of them will stay at home this summer. Home, of course, is not the nest. Right now, it’s just a useless pile of sticks. Home is the birds’ territory, the area in which they fly, hunt, perch, and sleep in.

Here in Ohio, a typical red-tail territory is about 2 square miles. I doubt that the Franklin Institute red-tail territory is that large, but the only way to know is to mark on a map every spot a hawk is seen flying or perched. That’s something that someone should be compiling, right now. After a summer’s work, a map with a bunch of colored dots will clearly show where the birds consider “home.” Then, the researcher can begin to connect perches and flight lines with what’s on the ground. This is not a random, stochastic phenomenon. These birds are pretty smart, spending their time only in what they consider productive and useful places and activities. No one should think that any of this is just the random, undirected, stupid behavior of a thoughtless animal. No, the brain processes of hawks are not mammalian or human in any way. But these are interesting and complex and successful in their own peculiar manner.

That’s part of the scientific romance in the study of this great species. I’m pleased that so many in Philadelphia have been smitten with this interest, while so many others can vicariously participate by way of the postings on this board.

My best to all. Keep the questions and observations coming."

-- John Blakeman