Subject: Re: Weird Urban Peregrine Prey (was: rare-bird "sighting")
Date: Dec 13 13:25:31 1997
From: Christopher Hill - cehill at u.washington.edu



On Fri, 12 Dec 1997, Michael Price wrote:

> So here's a two-cent's-worth series of interlocking speculations to account
> for this stuff: a) that Sabine's Gull are when migrating overland sometimes
> to often nocturnal migrants (apparently they're fairly closely related to
> Swallow-tailed Gulls Larus furcatus, which *are* nocturnal); b) both cuckoos
> are--no speculation here, we know--also nocturnal migrants as well as being
> fairly lousy fliers and c) that when it suits them, Peregrines are
> (partially) nocturnal hunters on those passing nocturnal migrants that would
> normally overfly otherwise.

Great - nocturnal hunting might explain a lot. Heaven knows what the
Cuckoos are doing at night - they're certainly vocal then, and for all we
know they've got elaborate aerial displays ;). Peregrines in the grand
canyon of the Colorado definitely come out at dusk ("bat-o'clock") to
chase pipistrelles, but I didn't know that they hunted in real darkness
until I read Martin Muller's post.

I'll add two more tidbits that may fit in somewhere. One is that
individual falcons may specialize heavily. A peregrine wintering in
Puerto Rico on a wildlife refuge where I worked left every morning at
first light for the coast a couple miles away, and seemed almost every
time to nail a cattle egret. A gyr in New Haven five or ten winters ago
subsisted as near as anyone could tell on 100% starlings, despite the
abundant pigeons, waterfowl, crows etc. nearby.

Second, these guys may well be commuting OUT of the checklist area to
hunt. That well monitored female peregrine in Springfield, Mass, raised
eyebrows one summer when she was unpaired by casually showing up and
hanging around another nesting pair in Boston, clear across the state
(which is only 90 miles, but still...). There'd she'd be in Boston during
the day once or twice a week, and back in springfield each night. If that
was the radius of her wandering, she covered a lot of acreage that summer.

I bet a the white wing spots on a Yellow-headed blackbird coming across
Elliot Bay in the moonlight look like a pair of tiny flashlights blinking.

Chris Hill
Everett, WA
cehill at u.washington.edu