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Friday, August 8, 2008

The Silent Disappearance of Local Marine Birds

I was inspired to return to writing about marine birds since this week I saw my first Bonaparte's gulls, marbled murrelets, and Cassin's auklets of the seasons. (The photo below is of a Bonaparte's gull flying around off my deck last fall.) Back on July 23rd I attended a lecture at The Whale Museum by Joe Gaydos of the SeaDoc Society. Here are some highlights:

First of all, what exactly is a marine bird? The broad definition is any bird that relies on the marine habitat for part or all of its diet is a marine bird. Using this definition, we have 128 species of marine birds in the Salish Sea, 24 of which are listed on the Endangered Species List.

Secondly, it's important to note that marine birds travel great distances. Some surf scoters tagged in Puget Sound, for instance, were documents as far away as Saskatchewan, Nunavut, and Alaska. So when talking about local bird declines, it's important to consider that we're looking at just a small piece of a species' overall range, and that they could simply be shifting the usage of their habitat.

One thing I learned that surprised me is that people hunt sea ducks. Not only that, but people may be hunting enough sea ducks to have an impact on local population abundances. Hunters can take only one Harlequin duck a year, but surf scoters are a different story and the state of Washington is currently reviewing its hunting regulations regarding this species due to up to a 50% decline in numbers in the last 25 years. How does one retrieve a seabird after its shot, I wonder? Is hunting done from a boat or from shore? I'll have to look into this at some point to satisfy my curiosity.

Another alarming fact was that as of this lecture, no one in the room had seen any marbled murrelets this year. Usually they are most abundant in August, and indeed pairs have been sighted in the last week, but it's kind of weird that no one saw any in June or July.

Here are few other interesting species-specific notes:
* Unlike many other seabirds, bufflehead populations are doing quite well. This is probably due to the fact that, unlike many other species, they have a very diverse diet and eat many small marine creatures instead of a select one or few. Terns, geese, eagles, and cormorants are among the other species experiencing a local increase.
* Pigeon guillemots are the one alcid species that is here year-round. Because of this fact, they may be a good indicator species for the health of the region.
* The highly sought after tufted puffin is a species so rare in the area many conservationists think our efforts would be better focused on birds that have a realistic chance of having a substantial population locally. Puffins used to breed on Bare, Skipjack, Flattop, and Puffin Islands. Now, there are probably a few on only Smith and Protection Islands.
* Species definitely experiencing a decline include the common murre, rhinoceros auklet, long-tailed duck, all three scoter species, goldeneyes, and loons.

Local marine birds are probably declining due to decreasing fish populations, but why is no one noticing? Why is the decline "silent"? Gaydos' suggested that unlike very distinct animals like the orca, the Stellar sea lion, or the bald eagle, most marine birds are very difficult to tell apart, especially in the winter. If a pigeon guillemot looks like a murre looks like a murrelet to most people, trends are not as easily observed.

Reportedly, local bait fish have been especially abundant in the last few weeks. It will be interesting to see what, if any, affect this has on local marine birds.


brooklebee said...

Hi Monika! I've been reading this blog ever since you linked to it from lj (via google reader), and enjoying the insight into your fantastic life in the San Juan islands. Your beautiful photographs definitely make me want to visit!

Monika said...

Hi Brook! I'm glad to hear you're enjoying the blog. I've been following your adventures in Europe as well through your blog and photos. You should make it out for a visit sometime, especially if you'll be as close as Vancouver.