Laura Erickson's For the Birds

Thursday, August 7, 2008

AOU Meeting

It's August, that time of year when the American Ornithologists' Union holds their annual meeting. This time it's in Portland, Oregon, held jointly with the Cooper Ornithological Society and the Society for Canadian Ornithologists. I wish I could be there for all the paper sessions and interesting events, but if I have to miss it, I at least have the next best thing, Hugh Powell's Round Robin blog. We at the Cornell Lab are redesigning our website, and to get ideas from the people who actually use the website, Hugh has been keeping a blog. This week while he's in Portland, he's been posting about interesting papers.

On Monday, he gave an overview of the meeting. On Tuesday he first wrote about the distressing news from Hawaii that the Hawaiian honeycreepers are fading fast. He attended a paper by the Smithsonian's Rob Fleisher about the tragedy of malaria killing the native birds on Hawaii--of the original 110 species of land birds on the islands, there are now only 31 remaining, and 20 of them are endangered. Interestingly, the form of malaria that is wiping them out is overall not a virulent form for humans today, though it did decimate the native Hawaiian humans when mosquitoes were introduced by ships during the late 1700s. Hugh also talked about how the native birds must live at elevations above where mosquitoes are, meaning that global warming is impacting them as mosquitoes advance higher with warming temperatures.

Tuesday he covered several topics. In his first post, he summarized one paper that discussed possible reasons why woodpeckers have larger brain sizes than similar sized birds. Then he talked about the all-day symposium about the effects of cats on birds. About one paper, Hugh writes:

Pete Marra, of the Smithsonian Migratory Bird Center, followed Gray Catbirds around three neighborhoods in Washington, D.C., and Maryland. His team, including a network of nearly 300 citizen-science volunteers, put tiny tracking devices on about 100 young catbirds just as they were leaving the nest. In a cat-free neighborhood in Bethesda, 65 percent of these nestlings survived their first two months in the outdoors. But in two DC suburbs with high cat populations, roughly six out of every 10 fledglings died over the same period. Most were eaten by cats – fieldworkers often caught the cats in the act, Marra said.

Deaths among the just-out-of-the-nest crowd add up. Standard ways of gauging a population’s health (whether it’s increasing or decreasing) base their estimates on how often nests are successful – but they ignore the differences in a young bird’s survival prospects. When Marra factored in the effect of cats, catbird populations that had appeared to be increasing were revealed to be declining.

Then, on a literally lighter note, he talked about one paper regarding American Goldfinch male plumage. The more brilliant yellows come from the carotenoid pigments in their food, but apparently there is a cost to this brilliance--high (but natural) levels of the pigments have a bad effect on goldfinch livers and muscles.

Then he summarized some interesting posters, including one about lead levels in eagles and ravens in Yellowstone National Park increasing dramatically right after hunting season opens in Wyoming. Birds are picking up lead bullet fragments as they eat carcasses and entrails left by hunters.

Yesterday he wrote about an interesting hour-long talk by Dr. Rosemary Grant regarding Darwin's finches still evolving, and hybridizing, and about two short sessions, one about bluebirds evicting Brown-headed Nuthatches from nestboxes, and about what happens when Alaskan King Eiders mingle with eiders from Siberia.

Hugh's an interesting and fun writer--his blog is really worth your time!

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