Gary,



Could you please be more specific as to what you mean by "seabirds" in your
request? The two examples you cited-- White-winged Scoter and Great Blue
Heron-are not what most of us consider "seabirds". That term is usually
confined to non-anseriform marine birds such as loons, grebes, tubenoses,
alcids, cormorants, and possibly gulls and terns.



Here in the Vancouver, BC area, the main food items of Bald Eagles-away from
salmon streams-appear to be waterfowl and gulls. It's hard to say whether
most of these were acquired by scavenging or by active predation, although
it seems certain that a large percentage were birds that were either dead
already or sick/injured.



However, as I'm sure you know, there are quite a few examples in published
literature of eagles attacking loons, cormorants, and other large birds on
the water. I've seen eagles pluck Surf Scoters off the water, as well as
lots of predation on coots on freshwater lakes.



So-are you interested in any cases of predation by eagles on marine birds of
any kind (including waterfowl and gulls), or just on seabirds in the narrow
sense (i.e., non-waterfowl diving marine birds)? Also, I would suggest that
unsuccessful attacks are worth recording as well as successful ones, because
even a series of unsuccessful attacks could result in the abandonment of a
heron or cormorant colony, or in the relocation of a flock of diving ducks
to a less hazardous location.



Sincerely,



Wayne C. Weber

Delta, BC

contopus at telus.net











From: tweeters-bounces at mailman1.u.washington.edu
[mailto:tweeters-bounces at mailman1.u.washington.edu] On Behalf Of Gary
Shugart
Sent: February-15-08 10:39 AM
To: tweeters at u.washington.edu
Subject: [Tweeters] request for eagle - seabird interaction observations



Hi All: Timely picture from Kelly of what appears to be a western grebe in
the talons, although I can't exclude a Clark's. I'm summarizing CBC data
looking at increases in eagles and decreases in seabirds in Puget Sound.
Most in the birding community are aware that eagles have done a number on
great blue heron heronries in the Sound, but in birding along the Vashon
Island shore I've noticed that there usually are several pairs of eagles
waiting or working the shore. This leads to the question are eagles
influencing the distribution of wintering seabirds?. The eagles disrupt
loafing and feeding activities, however, in 15 years, I've only seen one
success: an eagle nabbed an apparently injured ww scoter. A second
instances was of a GB heron grabbed but then lost by an eagle. The heron
crashed in the water and then escaped into a boat house at Tacoma Yacht
Club. I have seen eagles persistently harrassing scoters by hovering over
them and swooping down as the scoter surfaces but didn't to watch long
enough to see if the eagle got the bird.

The questions then are:
Have you seen eagles attempting to take seabirds?
What species was the eagle after?
Where?
When?

Please REPY OFF LIST to gshugart AT ups.edu <mailto:gshugart at ups.edu> to
reduce email volume. I'll summarize and post the results.

I am aware of the published studies of eagles harrassing seabird colonies.


Gary Shugart
Slater Museum of Natural History
University of Puget Sound
Tacoma, WA 98416
253 879-3356 (museum) 206 463-2169 (home)
gshugart at ups.edu
http://www.ups.edu/slatermuseum.xml
http://digitalcollections.ups.edu