For the Birds Radio Program: Birds in the News
Racing pigeon mystery, West Nile virus update, research on the color blue in birds and mammals, and an odd story about a birder who became mired in mud while tracking down some Great Blue Herons.
Birds in the News
Birds have been making international news quite a bit recently. Last week in Sweden, 2,000 homing pigeons were released in a pigeon race, their destination just a couple of hours, or 93 miles, away. But 1500 of them didn’t make it, and organizers of the race are still confused. Nothing like this has ever happened before. One representative of the pigeon club, Lars-Aake Nilsson, said “the weather was perfect—no rain, no thunder, and no strong winds.” He suggested that something might be happening with the earth’s magnetic field that threw the birds off course. But so far they haven’t turned up anyplace else, either.
As of July 20, 4 people have died from West Nile Virus in the United States—one in Iowa and Texas, and two in Arizona. Many more birds have died, though little money is going into testing carcasses now to track the disease, what with the anti-tax movement so devastating budgets for essential public services. But the Sage Grouse, a wonderful and quirky species of western sageland, which is on the endangered species list in Canada and should be on the endangered species list here in the U.S., may be suffering devastating consequences from the disease, according to a paper published this week in “Ecology Letters.” At five study sites in Alberta, Montana, and Wyoming, populations first exposed to the disease in 2003 had a 25% decrease in late summer survival of females. Eighteen carcasses of birds were found that tested positive for the virus. They collected 112 sage grouse after the outbreak, and absolutely none had antibodies, indicating that they had no resistance to the disease. Because habitat for sage grouse is being lost, the species now has many small, isolated populations rather than a large, healthy one, making the species especially vulnerable to devastating losses. My concern is that certain endangered species with extremely limited ranges, such as the Florida Scrub-Jay and the Yellow-billed Magpie, could be wiped out by this devastating bird disease. Cameron Aldridge, part of the research team, says, “Right now, our best option to help [vulnerable] species to combat the virus is to ensure that they have high quality habitats with few human impacts to ensure that populations remain productive and robust.”
In happier news, a recent issue of the Journal of Experimental Biology had a report by Yale and University of Kansas researchers who have been looking into exactly how blue feathers get their color. The blue does not come from a pigment but from the structure of the cells, which scientists have long believed scattered light the way the sky does. But their research turns this theory on its head. They found that the fine structure of blue feathers, like the structure of the odd, bright blue skin of the face and buttocks of the Western African mandrill and other blue-skinned mammals, precisely amplifies rather than diffuses the blue wavelengths of light. Under an electron microscope, collagen molecules from blue skin were more organized than they were in ordinary skin. They weren’t as monotonously arrayed as the crystalline microstructures found in iridescent feathers and insect skin, but neither were they diffusely distributed as they would be to scatter light as the Tyndall-Raleigh scattering produces blue sky. Apparently blue light waves are selectively amplified by the tightly spaced collagen fibers while other wavelengths of light cancel each other out. Any direction you view blue skin from, you see the same deep blue. After discovering this in blue mammal skin, the researchers tested it in blue feathers, and found the same phenomenon.
Finally, a birder in New York got literally mired in mud this week when she went off a foot path to get a closer look at some Great Blue Herons. She was stuck well over her knees, until she literally could not move. Fortunately, she had a cell phone, and called police. She didn’t know precisely where she was, but continued talking to them as they ran their siren, and could tell them if they were getting closer or farther away. On the Internet Bird Chat, some birders started telling of similar dangerous or awkward situations they’d been in, but everyone agreed that though they may have taken unusual risks to see new birds, not one of them would have done something like this for a bird as common as a Great Blue Heron.