Subject: Re: Gulls and Terns (was Bird Related Info)
Date: Mar 8 10:55:21 1996
From: Scott Richardson - salix


Kim McKillip asked about this:
>The U.S. Fish and Wildlife Service wants to kill about 4,000
>gulls by dropping poisoned bread cubes into their nests, so that endangered
>birds can nest and raise young on an island off Cape Cod.
>
>The service said it hopes that in four years there will be a gull-free area for
>plovers, terns and other birds on South Monomoy Island.

Chris Hill responded already, but I'll add two cents.
Terns are colonial nesters that once were distributed on many islands in
the Gulf of Maine. They were plundered for the millinery trade in the late
1800s, but began to recover after being protected by law. Until the 1930s
they did pretty well, but then they began a gradual decline. The drop in
their numbers corresponded with an astronomical increase in the number of
gulls (Great Black-backed and Herring) in the region. As Chris pointed out,
the gulls increased with "our" help; open dumps provided rich feeding
grounds for them.
Here's some data from Maine tern colonies, courtesy of the National
Audubon Society's Seabird Restoration Program:
In the 1930s:
8000 pairs of Arctic Terns; 6500 pr Common Terns; 275 pr Roseate Terns
In 1984:
1720 pairs of Arctic Terns; 2543 pr Common Terns; 76 pr Roseate Terns
In 1995:
5138 pairs of Arctic Terns; 5011 pr Common Terns; 153 pr Roseate Terns

The increase since 1984 stems from the efforts of members of the Gulf of
Maine Tern Working Group, a coalition of Audubon and other private
conservation groups and state and federal agencies. Their methods have
included predator control, which in part means the killing of gulls by
various means.
Gulls compete with terns for nest sites, but perhaps more importantly
they relish tern eggs and chicks. These tern nesting islands are in places
where lots of people spend vacations boating and getting away from it all.
Boaters landing on an island with a tern colony will cause the terns to take
flight in alarm and this is when the gulls move in. Far less fearful of a
bunch of picnickers, the gulls swoop into the tern colony, scarfing down
eggs and chicks to their hearts' content. The tern colony fails.
I spent the summer of 1991 on Jenny Island, a teeny island just off of
Cundy's Harbor, south of Brunswick, Maine. Audubon biologists knew Jenny
attracted a few terns to nest but pairs never had much or any success. That
May, gulls were poisoned (ref Chris' description of methods) and shot. A
warden (me) was stationed on the island to enforce a newly-posted no-landing
policy and to monitor the tern population. By June 20 (the GOMTWG census
date), 57 common tern pairs had nested. Productivity that year was 1.7 young
per nest, the best in Maine.
Since 1991, no more adult gulls have been killed and the number of nests
destroyed has dropped to single digits. Meanwhile, the Common Tern
population increased to nearly 500 pairs in 1994, with continued high
productivity. And endangered Roseate Terns moved in, too, with 16 pairs nesting.
It's almost all good news. Terns are coming from all over the northeast
to nest on Jenny Island, a rare safe haven from tourists and gulls.
Unfortunately, successful tern colonies are limited. Just 16 colonies in the
Gulf of Maine now support Common Tern colonies. Adding South Monomoy Island
to the list would unquestionably benefit the terns, as well as piping
plovers and other birds.
I'm looking forward to a brief visit to Jenny Island this summer; I can
barely imagine a nesting population 10 times as large as when I first
studied it.
(I think my two cents turned into two bits.)
--
Scott Richardson
NE Seattle
salix at halcyon.com