Monday, May 29, 2006

Blakeman on Pale Male genetics

One of the three orange-chested chicks at Cathedral of St. John the Divine
Photo by Bruce Yolton 5/26/06

Orange-chested nestlings at Fordham University [Bronx]
Photo by Rich Fleisher

Referring to my posting yesterday about the Cathedral nestlings and their possible relationship to Pale Male, John Blakeman writes:


I concur with Len Soucy of the Raptor Trust. I, too, have never seen eyasses with the orange or buff (or whatever saturated color it is) breasts of the Manhattan red-tails.
This strongly suggests that all of these birds are closely related. Population biologists would prefer a wider genetic base, with parents and genotypes of diverse origins. But so far, there doesn't appear to have been any significant inbreeding problems. Three eyasses on a nest, as now at the St. John the Divine cathedral, is a sure sign of both behavioral and genetic success.

Raptor biologists should note (as I do) the apparent close relationship of all of the Manhattan red-tails. Instead of being colonized by separate and diverse invaders, it now appears that Manhattan has been colonized first by our man Pale Male and now his progeny. The genetic vitality of the population is maintained by the apparently unrelated females, who are drawn into new Manhattan territories, such as this one at the cathedral, by Pale Male offspring males who discover and take up new territories on the island.

There are a number of valuable lessons in red-tail colonization of new habitats here. This doesn't happen often. It should be closely studied and described. It would be ideal to get genetic characterizations of all of the resident red-tails, from which reliable genealogies could be determined. But that would, at the least, require the retrieval of newly-molted feathers from known parents, or more significantly, the adults should be trapped and blood samples taken. Out here in rural areas, we would do this in an instant, with no harm whatsoever to either the birds themselves, or to their continued presence in the territories. But simple and harmless trapping of red-tails in New York City just isn't going to happen, so speculation, based upon known raptor biology, will be the continuing explanation for what we see.

And what I want to see is the continued and successful residency of red-tails in New York City, on Manhattan Island in particular, without the appearance of any genetic inbreeding problems. So far, so good.

These birds continue to amaze, particularly as a population, not solely as individuals.

--John Blakeman