Monday, April 16, 2007

Blakeman on how redtails catch so many pigeons in NYC

For good luck:
a photo of Pale Male and Lola's first chicks -- 2002 -- two weeks after hatching

Received today from John Blakeman:

I've been communicating with Jeffrey Kollbrunner in Queens, (
regarding his pair of nesting red-tails there. With NYC Audubon, he’s posted a live webcam of the nest where viewers can watch the pair closely. One of the eggs has hatched---perhaps two, by Monday.
Wonderfully, Jeffrey has described for me in detail how urban red-tails take so many pigeons. As noted many times, pigeons—not rats or squirrels or mammalian prey—are the primary food of all the NYC red-tails. This contrasts so markedly from the practices of rural red-tails, where the only pigeons ever taken are ones injured by cars or otherwise first disabled. When I first learned of Pale Male and the other NYC red-tails, I wondered how so many pigeons could be captured so easily by these big, sometimes lumbering hawks more noted for muscular strength, not speed and agility.
I hypothesized that Pale Male and the others must be strafing pigeon flocks while feeding en masse on the ground, taking inattentive young pigeons. Now, from Jeffery’s observations, I don't think that’s the frequent method. How the pigeons are taken is even more remarkable, and reflective of the adaptive intelligence of the red-tail.

Jeffrey tells me that to make their kills, his red-tails will spot pigeons perching on the sides of buildings, either while flying high over head, or from a distant perch. The pigeons will be perched on railings and narrow ledges, just as they would have perched on cliffs in their Middle Eastern lands of origin. On both rock cliffs and modern buildings, the pigeons feel safe from peregrine falcons who can only kill in the air. NYC pigeons almost surely spend more time perched on the sides of buildings than in any other place.

The hawks have figured out how to swoop quickly and unseen from around the corner of a pigeon-laden building and grab the startled birds just as they take off, before they attain any speed. This is a wonderful and intelligent combination of stealth, strategy, and speed, a hunting technique we never see out here in rural areas.

The hawks have cleverly learned to exploit the abundance of urban pigeons, another manifestation of the species’ predatory intelligence. Twenty years ago, no raptor biologist or falconer with red-tail experience would have ever thought so many pigeons could be taken so consistently by these hawks. None of us would have ever presumed the species so able to enter, adapt to, and thrive so successfully in urban environments dominated by turf, tar, and buildings, not meadows and forests.

I thank Jeff for explaining how NYC red-tails so commonly capture pigeons. I now have a more complete understanding of how and why these birds succeed in urban environments. Surely a few pigeons are caught in “brush-crashing” stoops into the foliage of trees where a perched pigeon has been discovered. And some may be taken as I initially presumed, with a high-speed, low-angle strafing plunges into flocks on the ground. But the speedy plucking of perched pigeons off the sides of buildings is the real story. For me, the murk and haze of the pigeon-capture method is lifting.

Brilliant birds, these.

–John A. Blakeman