Wednesday, July 05, 2006

Why doesn't he fight back:? Blakeman replies

Dear reader: I'm unable to upload the picture Karen Kolling refers to below [or any picture, for some reason.] You can go to and find the grackle/hawk sequence in the June-December 2006 page, July 4 sub-section. Marie

Karen Anne Kolling writes:

Below's a picture from Lincoln's web site. It looks like the grackle actually hit the young redtail's head? I am wondering why the hawks put up with the apparently frequent harassment from smaller birds as opposed to sticking out a claw or beak and dispatching them...

John Blakeman replies:

Yes, the grackle almost surely landed for an instant on the hawk's back. The hawk just sat there and endured this harassment. I've seen this many times, both in wild hawks like the one pictured here, and also with my captive falconry birds perched out in my backyard. This scenario is familiar to all who have watched red-tails in the summer in the wild.
Why doesn't the hawk just quickly plunge a fistful of talons into the pesky little grackle? It's not as easy as it might appear. The grackle remains in the hawk's leg length for just an instant, and for the hawk to extend its leg would require that it shift its weight onto the other perching leg. In short, red-tails aren't built to easily thrust out a leg while sitting on a perch. The grackle "knows" this (No, it doesn't "know" this as we might -- it is only genetically programmed to shoot in and out quickly, avoiding capture.), that the hawk simply can't leap up and grab it with any ease while perched. The grackle is doing this because it's still in breeding mode. The blackbird probably has fledglings in the neighborhood, and by harassing the hawk as it is, the raptor's attention is diverted from any little grackles nearby. In August, these diversionary attacks generally stop, when vulnerable little bird youngsters are fully on the wing and safe from the larger, lumbering hawk. This is a seasonal event.
The photo is interesting for two other points. First, this hawk looks to be a female, from the thickness of the tarsus, the "ankle." To me, I'd bet this is a female.
But the more interesting observation is the emerging red tail feathers. Viewers should note that the red tail feathers are not as long as the brown, older banded ones. The bird was hatched in 2005. She is a second year red-tail, now in its first molt. The two central "deck" feathers have replaced the immature ones.
The shorter length of the adult, red tail feathers is normal. The same thing happens with the long primary feathers of the wings. This is why immature red-tails often look larger than their parents. Birds in their first year don't have completely developed, strong wing muscles, so their wing and tail feathers are a tad longer than they will be in adulthood. Immatures have lighter wing loading, spreading the body weight over a larger feather area. This helps them fly more easily with their weaker musculature. In the second year, with adult, fully-developed muscles, shorter wings and tails can allow greater maneuverability.
Experienced red-tail watchers can usually separate soaring immatures from adults merely by the respective tail lengths. Long-tailed red-tails are immatures. Adults are a bit more compact, while being also much more powerful.
The red tail feathers in the picture are fully grown, a bit shorter than the older brown feathers being replaced during the molt this summer.
And this bird is one of the few that was able to survive its first winter. Red-tails have a general 60-80% first year mortality. Only one or two red-tails out of five that leave the nest are able to survive their first year. This bird, where ever she was raised, is already a winner. The harassment by the grackle is inconsequential. Her greater problem next spring will in finding an open territory and a mate.
--John Blakeman