The tale of Ray Bosse, Brad Allen, and the banded eiders

8 04 2010

Since the SEANET blog has now been renamed “The Ray Bosse Show,” today’s post will reflect our new focus on all Ray Bosse, all the time. Last week, your SEANET blogger reported on Ray’s 100th (really 60th or so) dead bird. The carcass found on that now-not-so-momentous day was that of a female Common Eider.

Ray reported the band, and the info is in: this adult female Common Eider was banded on May 20, 2009 on Orrs Island in Casco Bay, Maine.

Brad Allen (right) with a banded eider near Orrs Island, Maine.

The researcher who banded the bird is Brad Allen, Bird Group Leader for the Maine Department of Inland Fisheries and Wildlife. Anytime a banded Common Eider turns up in SEANET territory, you can be just about sure that Brad banded it. We asked him for some information on his research’s scope and purpose, and he very obligingly provided it.

He first explained the reason that his work focuses on adult eiders: they are a long-lived species in which experienced breeders provide population stability. While chick survival can fluctuate substantially from year to year, the population will be relatively insulated from those changes as long as the adults survive and return to nest year after year. Brad has determined that the greatest threats to the adults in the population are disease and high harvest (hunting) rates. He explains,

“Eiders in the northeastern U.S., primarily the American race or [Somateria mollissima] dresseri, are the most hunted sea duck on the east coast …the average harvest in Maine in recent years has been approximately 17,000 birds. Besides a deep respect for this wonderful duck, my primary concern was to determine if current hunting harvests are sustainable given the other sources of natural mortality.”

To that end, over 11,000 eiders have been banded in Maine since 2002.  In terms of band recoveries, Brad tells us, “Hunters of course report the greatest number of bands in our dead bird recovery database. The second most frequent recovery is similar to Ray’s: a banded bird found dead (generally of unknown cause) on a beach somewhere south of the banding location. The third most frequent recovery are birds that we
find dead on our study islands that have been killed and eaten by bald eagles. Bald eagles haven’t figured out how to use the 1-800- 327-2263 number yet, but we still find several each year, indicating to us that eagle mortality of nesting eiders is significant.”

While previous banding studies focused on female eiders captured on the nest, Brad and his team have devised a technique that allows them to capture male eiders as well, by targeting them while they are molting, and therefore flightless, out on the water. Nearly 5,000 males have been banded to date, allowing survival estimates to be made for both sexes, and since hunters preferentially target males, getting males banded is crucial to understanding the magnitude of hunting pressures on the eider population.

Eiders being rounded up for banding. The technique works so well, Brad has to let half go without banding them!

Any banding study relies on members of the public, be they hunters, Seanetters, or otherwise, to report the bands they recover. Brad’s work is no exception, and he wanted to offer this word of appreciation: “Ray, thank you and all the others who take the time to find, read, and report a banded bird when it is encountered.”

That’s it for today’s edition of the Ray Bosse show. The SEANET blog will return with it’s usual sort of programming next week. Unless Ray does something else warranting recognition between now and then. Not an unlikely prospect, at this rate.

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One response

9 04 2010
Jenette Kerr

Most interesting entry, Seanet Blogger. I wasn’t aware of this study and Common Eiders are,well, common on my outer Cape Cod beach ! Thanks–

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