Monday, August 01, 2005

Redtail Eating Habits: Q & A

Donna asks a question :


I've seen Big try to swallow a small rat,
unsuccessfully. Charlotte had to pull it back out.
Jr. seems still to be preparing the food in some way
before bringing it to the young.

We were watching one of the fledges at dusk. Jr.
appeared a number of times. In one case he had a
mouse, or something quite tiny in his beak. Then we
lost track of it. Busy night of people stopping by,
asking what we were looking at, looking through the
Scope; hard to keep track. Eventually the fledge
"found" something in a tree and ate it. I'm not sure
if it was something stashed or a leftover as by then
it was too dark to see clearly, but interesting that
Jr. might be placing food to be "found" by the young.
Have you seen that?

Earlier the fledgling had flown down to the ground
near the stone wall of Central Park near a squirrel.
The squirrel rushed him and the fledgling hightailed
it back to the tree.

Speaking of squirrels I don't know that I've ever seen
Jr. with a squirrel. Charlotte yes, but not Junior.
Lola takes more squirrel than Pale Male but he does
take some. Size differential? Bad experience with a

Thank you,

Blakeman answers:

I've mentioned it before (somewhere), that red-tails (and other hawks) are poor eaters, that they only ritualistically, or mechanistically tear their food. They don't eat with any refined techniques. It's pretty much just to reach down and grab something and tear it away, then try to swallow whatever was torn.
For the new young birds, even this level of dining refinement isn't present. They just try to wolf down anything they can get into their mouths. Remember the photo with the long feathers stuck in the mouth? Case in point.
The young birds try to wolf down a big object, but it finally gets caught in some choking receptors somewhere in the throat and the object is coughed back up. To see this up close, as I have so many times, is to become alarmed. So often, it appears that I should reach in and do a Heimlich. But the bird always manages to extricate the overly-large swallowing. Then, the young bird often tries to swallow the object in exactly the same manner again, ending exactly as before. As you saw, the big object, perhaps a rat pup, falls to the ground. The bird looks at it puzzlingly and just wonders why it didn't go down. Finally, it realizes that it has to step up on the food and rip it apart with it's beak. But if talons aren't firmly set into the object, the beak merely pulls the food up between the toes into free air. The bird then tries to swallow the object once again, yielding exactly the same choking response.
To watch this spectacle of coarse raptor dining is to wonder how the young birds ever learn to successfully eat. Somehow, they do. But you've seen a bit of the complications the first year birds have to work out in their first few weeks out of the nest. Somehow, it all resolves and the birds will be able to feed effectively, if not delicately. Adults sometimes revert to inordinate wolfing, too. Red-tails are incapable of fine dining.
About the squirrels. In rural areas, these arboreal rodents are marginal and infrequent red-tail fare, especially the larger fox squirrel. The squirrels of Central Park, I believe, are all the slightly smaller gray squirrels. Nonetheless, each species can be challenging prey, even for the muscular red-tail. Squirrels are hard to kill. They have lightning-fast, extremely powerful, and agile teeth and jaws. Unless a hawk can instantly grab the head of a squirrel and restrain its biting, the bird is likely to encounter a vicious bite that can severe a tendon or split a bone.
Additionally, squirrels have skin that is almost impervious to the penetration of the hawk's needle-sharp talons. It is difficult for a red-tail to sink a talon or two into a vital organ. And since most of those are in the thoracic (chest) cavity, the squirrel's head may be free to fling about and render multiple bites on the toes and tarsus (ankle) of the hawk.
Although squirrels appear to be readily available hawk food, these rodents are formidable prey. Your indication that you've never seen Jr. with a squirrel is very accurate, I'm sure. You note that squirrels have been seen mostly with the two females, Lola and Charlotte. That exactly matches the experiences of most falconers who pursue squirrels with red-tails. The smaller tiercels (males) just don't much like to take on squirrels The big hens will, from time to time.
Having watched red-tails hunt, I'd stay away from squirrels if I were a red-tail. They are dangerous, difficult to kill, and hard to rip open for the underlying flesh. You noted that a squirrel ran right at a fledgling on the ground. She was wise to retreat. Squirrels are formidable. A wise red-tail stays away from them except only when it knows it has the upper hand. Lola and Charlotte know their prey and how to kill them. Smart ladies, these. Their husbands are smart, too, in generally avoiding squirrels.

John A. Blakeman