OAKLEY - Something is killing hundreds of ducks along Land Creek Springs, a waterway near Oakley.

"We've never seen anything like this," said David Parrish, regional supervisor with Fish and Game. "For this localized an area, it's a pretty big event."

The death toll has risen to more than 1,000 since early this week, and dead ducks continue to pile up. Wildlife experts are puzzled and hope an investigation finds the cause quickly before the regional duck population is decimated or dead ducks begin turning up in other Idaho streams.

Late last week, hunters found several dead mallards near the stream and contacted officials at the Idaho Department of Fish and Game. Conservation officers responded that day and found 10 dead ducks. They returned Monday to discover more than 500, many of them logjammed in the stream.

The investigation includes Fish and Game, the U.S. Fish and Wildlife Service, the U.S. Department of Homeland Security, the Department of Environmental Quality, the Department of Agriculture and South Central District Health.

But it hasn't turned up much.

Preliminary lab results from Boise show that many of the dead mallards had bacterial infections. And some birds still alive near the stream, Parrish said, show signs of respiratory distress.

Tissue samples from the birds and water samples from the stream have been sent to labs across the state and region and to a Fish and Wildlife lab in Wisconsin. Results are expected before the end of the week.

Now, however, experts are scratching their heads.

The dead birds include local and migrating ducks. Parrish said it's possible a sick duck from out of the area transmitted a bacterial infection to local ducks, though he said it's unusual to see this many birds die at once.

A conservation educator for Fish and Game, Kelton Hatch said he's heard of 50,000 birds dying of botulism, but he's never seen this many dead ducks in Idaho.

Another possibility is that the birds ate grain that was illegally tainted by farmers trying to kill starlings. Intestinal-tract samples sent to a lab will tell investigators whether poisoned grain played a role.

A third possibility is avian influenza, though wildlife experts say the ducks' symptoms are not consistent with bird flu. Homeland Security is involved in the investigation in the remote chance bird flu is killing the ducks.

"But quite honestly, we don't know what's killing them at this point," Parrish said.

Signs have been posted near the stream warning hunters about eating waterfowl harvested in the area.

Anyone with information should contact Fish and Game at 324-4359.

Times-News staff writer Matt Christensen covers natural resources. Contact him at 735-3243 or at matt.christensen@lee.net.