Hundreds of eared grebes died and an estimated 5,000 more were rescued Monday after they apparently mistook wet pavement for water during the foggy, early morning at the U.S. Army's Dugway Proving Ground.
"Security guards said it started to snow about four in the morning and that's when they started seeing the birds do a hard landing," said Robbie Knight, wildlife biologist for the Army base.
The water birds, with feet at the backs of their bodies, skid to a stop on water and cannot easily take off from earth.
When they hit ground instead of water, they tumble. "We've had birds break their legs, necks and backs," Knight said.
It's unclear, Knight added, whether wind forced the birds to the ground, or whether they were disoriented in the dense fog. Visibility was less than 20 feet.
It's likely that the first eared grebes on the ground called to the others, and that led them to believe they would find water.
The grebes migrate in huge flocks, Knight said, so "when they start to come out of the sky, they really come out of the sky."
He estimated the birds came down over a swath of land two miles wide and 30 miles long, north to south. Some were found at the Skull Valley Indian Reservation to the north of Dugway. Dugway is 84 miles southwest of Salt Lake City.
It was the second time in 17 months that the migratory birds died after hitting pavement in Utah, where the Great Salt Lake provides a summer home.
In December 2011, 1,500 of the birds died after hitting a Wal-Mart parking lot and other paved surfaces in Cedar City. Another 3,500 were rescued.
The birds are protected under the Migratory Bird Treaty Act, so Dugway and the Utah Division of Wildlife Resources had to get a permit Monday through the U.S. Fish and Wildlife Service in Denver to rescue the surviving birds, euthanize the severely injured and burn and bury the dead.
Knight said he expected to havefirmer numbers Tuesday on the dead and rescued birds.
It took 60 workers, including 25 soldiers, much of the day to gather the surviving birds, which were carried in the backs of pickup trucks to ponds on Dugway and to the Utah DWR's James Walter Fitzgerald Wildlife Management Area near Stockton, south of Tooele.
The rescuers just picked up the birds by hand from behind. While some birds tried to flee, they didn't get far because they are not designed to walk on land.
Dugway is roughly 40 miles south of the Great Salt Lake, and it's the peak season for the eared grebes to return from the Southwestern states or Mexico to spend the summer in Utah.
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