Blakeman on robins as redtail prey
Photo courtesy of http://www.palemale.com3/8/07 [click on photo to enlarge]
Marie,
I was interested in today's photo on PaleMale.com of one of the hawks carrying a partially-consumed adult robin. Red-tails don't capture adult robins---or at least that's the conventional wisdom. This is further evidence that the Central Park red-tails have perfected some new and effective capture techniques.
I'm certain that a big red-tail can't capture a fully healthy, on-the-wing robin. When pursued in the air, the little songbird just wheels around in a tighter flight circle and hawk slides past in its weight-induced larger flight radius. As with the numerous pigeons, I think the only way the big hawks could capture a robin would be to stealthily ambush the little bird at speed while it is hopping across a lawn. Upon dropping from a high perch the hawk can reach 50 to 70 mph or more, scooting just above the ground. The robin in question was inattentive and thereby donated its accumulated proteins and lipids to an organism higher in the food web.
For those of us who know how these hawks hunt and take prey in rural areas, the robin capture, as with all of the previous pigeon ones, is just remarkable.
There can be no wonder why this species inhabits habitats from northern Mexican deserts on up to sub-alpine and northern taiga forests, and everywhere else, in ice-free North America. The bird adapts, as it has so well in recent years in New York City (and now in other urban habitats).
Personally, I can't understand why the species isn't circumboreal, living, as does the kindred rough-legged hawk, across all of northern Europe and Asia. The species must surely have recently evolved here, right after the Ice Age. Why it hasn't yet jumped across the narrow Bering Straights and taken over Eurasia is a mystery to me. If the bird can survive so splendidly in Central Park, the rest of the temperate world should be its oyster (well, vole or gerbil), so to speak.
--John Blakeman