Subject: On the Duwamish - 2-20-2004 - Falcon-Accipiter Interaction
Date: Feb 20 13:50:17 2004
From: Desilvis, Denis J - denis.j.desilvis at boeing.com


12:06pm start; water level <7ft and incoming tide
12:42pm end (and I wanted to stay outside but work called)

Tweeters,
Today was a first for me: I saw a PEREGRINE FALCON kleptoparasitize a COOPER'S HAWK. At 12:07pm I saw the male Cooper's directly south of me on the rocks immediately above the mud shore tearing apart what appeared to be a Rock Pigeon. As I watched through my scope, feathers flashed and what turned out to be the Peregrine Falcon blasted down displacing the COHA, which jumped up into the air and came down about 3 ft to the left of the falcon. The falcon spread wings over the prey and faced the hawk, which stretched forward, but then backed off. After about 30 secs, the falcon started tearing into the prey, and turned away from the hawk, facing north (downstream). The hawk seemed to settle back, standing upright about 3-4 feet away. The falcon continued to tear into the prey until 12:17pm, at which time the falcon started head-bobbing and acting very agitated. It defecated, then crouched and sprang into the air carrying a large chunk of prey, and flew low--but rising--downstream in front of me. It then settled on the east power tower about half-way up on a major crossbeam. When I looked back, the Cooper's Hawk had reclaimed what remained of its kill. At one point, the COHA hopped down the bank and picked up a largish bone that must have had meat on it because the hawk started worrying at it. By 12:36pm, the COHA was reduced to picking around the area for bits; and by 12:40pm, the falcon had moved about two feet to the left on the crossbar and appeared to be preening.

For Martin Muller and Brian Bell: ref your conversation with me the other night--the Peregrine was struggling a bit carrying the a major piece of the Cooper's Hawk kill, which reinforces my thought, and your supposition, that this PEFA is most likely a male.

To tell you the truth, trying to pick out other birds during my time outside was not uppermost in my mind!

Birds seen during this scan include the following:
Canada Goose (2 near the goose exclusion area; 6 as flybys)
Gadwall
Double-crested Cormorant (2)
Cooper's Hawk
Peregrine Falcon
Glaucous-winged Gull (2)
Rock Pigeon (12; not including that which was prey)
American Crow (2)
Black-capped Chickadee
Bewick's Wren (2)

May all your birds be identified,

Denis DeSilvis
Seattle, WA
mailto:denis.j.desilvis at boeing.com