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Wind power not easy win for birders

Birders tend to be sympathetic to whatever protects the ecosystem. For that reason, "clean" energy schemes that provide power without pollution should be an easy win with the birding community. Ridgetop wind turbines, however, have many birders worried. ..."When birds are migrating, most are a lot higher off the ground," Dawson continued. "But they clear the ridges at a lot lower altitude than they would when flying over flat ground.

Ridgetop turbines could pose threat to birds during migration season

Birders tend to be sympathetic to whatever protects the ecosystem. For that reason, "clean" energy schemes that provide power without pollution should be an easy win with the birding community.

Ridgetop wind turbines, however, have many birders worried.

Tall structures are known to kill birds during migration season, as night-time migrating passerines smash into concrete, glass or metal, littering the ground below with their bodies.

Just how dangerous to migrating birds are proposed wind turbines on Appalachian ridges?

Wildlife biologist Deanna Dawson, who works at the Patuxent Wildlife Research Center in Laurel, Maryland set out to find answers a few years ago.

She's analyzing the data she collected over five migration seasons ending in the fall of 2007, and hopes to have a report ready by the end of the year.

Warblers and other small birds migrate at night, many emitting characteristic flight calls that can be heard on the ground even though the birds themselves can't be seen.

If you know the flight calls, you can sometimes identify a dozen or more species in a few hours of careful listening on dark nights.

Dawson hit upon the idea... more [truncated due to possible copyright]  

Ridgetop turbines could pose threat to birds during migration season

Birders tend to be sympathetic to whatever protects the ecosystem. For that reason, "clean" energy schemes that provide power without pollution should be an easy win with the birding community.

Ridgetop wind turbines, however, have many birders worried.

Tall structures are known to kill birds during migration season, as night-time migrating passerines smash into concrete, glass or metal, littering the ground below with their bodies.

Just how dangerous to migrating birds are proposed wind turbines on Appalachian ridges?

Wildlife biologist Deanna Dawson, who works at the Patuxent Wildlife Research Center in Laurel, Maryland set out to find answers a few years ago.

She's analyzing the data she collected over five migration seasons ending in the fall of 2007, and hopes to have a report ready by the end of the year.

Warblers and other small birds migrate at night, many emitting characteristic flight calls that can be heard on the ground even though the birds themselves can't be seen.

If you know the flight calls, you can sometimes identify a dozen or more species in a few hours of careful listening on dark nights.

Dawson hit upon the idea of pointing microphones straight up into the sky at 31 different mountaintop sites over a three-state area and recording the results.

By painstaking "manual" listening as well as software analysis, she hoped to get an idea of how many birds were passing over southern Appalachian ridgetops, and at what altitude.

She refined the technique by adding portable marine radar units that gave her data on by how many feet migrating birds cleared the ridgetops during spring and fall movement.

"We found some interesting things," Dawson said. "In both spring and fall of 2006, over 40 percent of what [the radar units] detected was flying within 300 meters of the ground.

According to Dawson, migrating birds are clearing Appalachian ridgetops by margins lower than previously guessed. Consequently she believes that proponents of wind power may have been too optimistic about possible mortality from bird strikes.

"When birds are migrating, most are a lot higher off the ground," Dawson continued. "But they clear the ridges at a lot lower altitude than they would when flying over flat ground.

"I can't say that lots would be killed, but I think there's reason for concern in the Appalachians."

Dawson says that bad weather is the wild card that might make ridgetop wind farms dangerous to migrating birds.

"With radar and sound recorders we don't have specific altitudes, but I feel that anything flying within a couple of hundred meters of the ground is at risk," she said. "Weather conditions influence their flight, so on bad nights they could be within that zone where they get struck."

One of Dawson's most productive sites was along the ridgetop road on Bald Mountain in Craig County, where she got sound from critters besides migrating warblers.

"Just down the ridge from Bald Mountain is a really good site for whippoorwills," she said. "I've got some pretty amusing recordings of bears. You can hear them dismantling the thing, and in some cases they missed a microphone and I got the whole encounter. I've got some nifty recordings of coyotes and owls, too."


Source: http://www.roanoke.com/outd...

MAY 21 2010
http://www.windaction.org/posts/26418-wind-power-not-easy-win-for-birders
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