RESEARCH at SML section:
Ecology of Great Black-backed and Herring Gulls
Image courtesy of Michael Brothers.
Observing Nature's Raucous Harbingers of Ecological Change
Background information:
Gulls are seemingly everywhere, but how much do we really know about
them? What ecological roles do they play in the environment?
Gulls
are familiar elements of contemporary coastal communities, but this was
not the case one hundred years ago. During the 18th and 19th centuries,
gulls were extensively hunted for feathers and eggs, and breeding
colonies were nearly eliminated along the Atlantic coasts of North
America and Europe. Seabirds were protected from hunting in the United
States in the early 1900's and dramatic increases in populations of
some species have occurred throughout the North Atlantic. In New
England, populations of Herring Gulls (Larus argentatus) and Great Black-backed Gulls (L. marinus) increased substantially and currently breed on hundreds of offshore islands.
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The overarching, long-term goals of this study are to understand the interactions between Herring and Great Black-backed Gulls, their population trends in the Gulf of Maine, and the effects that these two species have on coastal marine communities of New England.
As part of this study, Dr. Julie Ellis (Tufts
University) initiated a gull banding program during the summer of 2004
on Appledore Island with funding and volunteer assistance provided by
the Earthwatch Institute (http://www.earthwatch.org). In this first
year of the project, 30 adult Herring Gulls and 60 Great Black-backed
Gulls were banded. Since then, over 1,000 gulls (chicks and adults)
have been banded and numerous banded birds have been re-sighted by the
public in several states along the East coast (including NH, MA, CT,
NY, NJ, MD, NC, FL).
How do we capture adult gulls? Adults are captured in May, when they
are incubating eggs. We place a "walk-in-nest trap" (a chicken wire
cage with a single opening on one side) on top of the nest; the gull
enters the trap through the side.
Once the bird has settled down on the its eggs, we quickly approach the trap and remove it from the nest, then gently extract the adult and place it into a cloth cone in order to restrain it and prevent injury. Each adult is then given a numbered metal band and a color band for easy identification in colonies and at far flung locations off the island.
Public
sightings of juvenile and adult gulls will help us to determine: where
gulls go in the winter, how far juveniles disperse during their first
few years of life, the survival rate of adults and juveniles of both
species, and behaviors (e.g. foraging, scavenging, aggressive
interactions) of gulls when they are not in the breeding colony at
Shoals Marine Laboratory. This information will contribute
substantially to our knowledge of these common, but underappreciated
birds.
Dr. Ellis plans to band more adults and chicks at the Shoals, and to continue studying the role of these birds in coastal communities in New England.
Contact information:
Julie C. Ellis, PhD
Cummings School of Veterinary Medicine
Tufts University
Dept. of Environmental and Population Health
200 Westboro Rd.
N. Grafton, MA 01536
julie.ellis "at" tufts.edu
