November 30, 2008
Hazing Keeps Swans From Lead-Filled Lake
After years of gathering dead carcasses of Pacific Coast trumpeter swans, and examining their lead-poisoned livers, wildlife biologist Mike Smith became convinced the only way to save the birds was by hazing them.
So he kept vigil with a night-vision scope, a laser and a noisemaker in a makeshift watchtower behind Judson Lake, on a mission to scare the swans away. Smith believes the lake, with its bottom full of shotgun pellets that have killed hundreds of the birds, is the likely source of the lead poisoning.
"It is bird harassment for a few moments of their life, but it certainly seems to extend their life," Smith told the Associated Press.
After hundreds of trumpeter swans began dying in recent years, experts tracked the problem to the shallow 100-acre Judson Lake straddling the U.S.-Canadian border. Although lead shots have been prohibited for waterfowl hunting since 1991, wildlife experts believe the swans were swallowing leftover pellets from the mud-covered bottoms of lakes and wetlands.
The lead enters the birds' bloodstream and paralyzes their internal organs, killing them within weeks, Smith said.
"All indications are that this is a major source," Smith said, referring to Judson Lake.
"We know there's lead here. Since we've kept them off, the mortality has gone way down."
Fewer swans have died in southern British Columbia and northern Puget Sound since Smith began hazing two years ago. Roughly 100 swans died of lead poisoning in each of those years, half the five-year average before the hazing began. Since 1999, nearly1,600 swans have died of lead poisoning in the region.
"They're huge, big and white," Martha Jordan of the Trumpeter Swan Society told the AP.
Indeed, trumpeter swans are North America's largest waterfowl.
"When they're dead, you notice them."
The swans typically make their way to northwestern Washington and southwestern British Columbia in early November. Seventeen percent of the world's population spends the winter in the Pacific Northwest before migrating in April to central Alaska.
In recent decades the native trumpeter swans have made a comeback. The state department of fish and wildlife counts roughly 8,000 swans in the area today, compared with just 100 during the early 1970s.
According to Smith, just one or two pieces of shot can kill a swan, and most of the tested birds had ingested an average of 20 whole pellets.
"When you see one up close ... and get some idea of just how big and beautiful they are and then to go and see them succumb to as horrible a death as lead poisoning, it's quite heart-wrenching," Smith said.
Scientists with the U.S. Fish and Wildlife Service, the University of Washington, Washington Department of Fish and Wildlife, Canadian Wildlife Service and Trumpeter Swan Society trapped and radio-collared nearly 300 swans to identify the source of the lead.
They gathered dead carcasses, obtained blood samples and monitored the birds' patterns. They also took hundreds of core samples from the birds' forage and roost sites, and discovered high lead density in areas, such as Lake Judson, the birds frequently used.
"We feel really good about Judson Lake and what we've been doing there," Jennifer Bohannon, a biologist with the state Department of Fish and Wildlife, told the AP.
However, "we need to come up with a long-term solution," she added.
"I don't think hazing year to year is the answer. That's the challenge that lies ahead."
Wildlife officials and others are now working to establish a cleanup strategy.
While swan hazing has contributed to a reduction in overall deaths in the area, scientists found unexpected deaths last year in Skagit and Snohomish counties, north of Seattle.
It is not yet clear whether the trumpeter swans acquire lead in the north and fly south to die, or have come upon new sources of lead. Scientists are now monitoring other lakes as a result.
"We went to nontoxic shot in 1991 and how many years later we're still losing these animals to lead shot," said Jordan.
"You've got to know there are more lead from other sources," she said, adding that lead shot is still legal for hunting other birds such as pheasant or quail, as well as skeet or trap shooting.
Smith and his colleagues will haze Judson Lake until January, when the water level becomes too deep for the swans to access the bottom of the lake.
Smith typically hears the swans' bugle-like honks before he actually sees them from his makeshift tower. After eating corn stubble and winter wheat crops in nearby farms, the swans try to roost on the lake at night.
For times when his noisemaker doesn't scare the birds away, Smith shines a red laser at the birds to get them to flee. As a last resort, he physically chases them away with his airboat. Simply starting up the loud engine is typically enough to make them go, he said.
Within several hours, Smith recorded a total of 34 swans scared away from the lake.
"You learn patience," Smith said.
"It's like fishing for birds."