[CT Birds] Great Cormorant decline
boletebill at yahoo.com
Tue Feb 9 11:31:09 EST 2010
Good info from greg on the G Cormorant decline in the NE.
This is an interesting development and one that bears watching. If true GC could become a rarity in CT as BE's continue to come back.
Without getting too far ahead of myself here it's tempting to speculate that the rapid expansion of G Cormorants into the NE since the 1950's may have had a lot to do with the absence of Bald Eagles.
One common interaction between BE and GC that I see on the CT river is that when GC catch a large fish they have to surface to swallow it and BE are on the watch for this and dive on the GC forcing them to abandon their catch. I guess you could call this water surface piracy.
"For those who hunger after the earthly excrescences called mushrooms."
--- On Tue, 2/9/10, greg hanisek <ctgregh at yahoo.com> wrote:
From: greg hanisek <ctgregh at yahoo.com>
Subject: [CT Birds] Great Cormorant decline
To: ctbirds at lists.ctbirding.org
Date: Tuesday, February 9, 2010, 10:20 AM
I read somewhere in the past year (but can't remember where) that in Maine and/or the Maritimes the burgeoning Bald Eagle population is reducing the Great Cormorant population through predation. A quick look on the Web turned up the following on a science Web site:
"On the rocky islands off the Maine coast, recently recovered bald eagles are eating rare great cormorant chicks. In the 1960s there were 400 Bald eagle pairs in the entire United States. Now, there are 500 pairs in Maine, the largest population in the Northeast. Bald eagles are no longer technically endangered, but they’re still protected by the Migratory Bird Treaty Act and the Golden and Bald Eagle Protection Act. (In other words, it’s illegal to kill a bald eagle.)
Great cormorants aren’t technically endangered either, but there’s only one place they nest in the United States—the rocky islands off the coast of Maine—and their numbers are dropping quickly. In 1992, there were 250 great cormorant pairs in Maine. Now there are 80, thanks mostly to harassment and predation by bald eagles. The bald eagles are supposed to be eating fish, but overfishing has made fish rather hard to find. With their preferred prey playing hard-to-get, bald eagles have turned to something easy—great cormorant chicks."
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