The two birds, a common eider and a spectacled eider, were found near the mouth of the Kashunuk River on the Yukon Delta National Wildlife Refuge in 1992. Analysis of their remains indicated fatally high concentrations of lead in their livers. Ingestion of lead shotgun pellets during feeding is probably the most common cause of lead poisoning in waterfowl, raptors and other birds. The common eider still contained shotgun pellets in its gizzard, the government biologists noted.
Populations of spectacled eiders have declined in recent years and the species will soon be formally listed as threatened under the Endangered Species Act.
"We knew we had some problems with lead shot in southcentral Alaska" said Bob Leedy, Chief of the U.S. Fish and Wildlife Service Division of Migratory Bird Management in Anchorage. "The discovery that lead poisoning also is occurring in western Alaska is bad news, but it should provide extra incentive to all concerned hunters to use nontoxic shot."
A recent study by the State of Alaska Department of Fish and Game revealed high rates of lead shot ingestion by waterfowl in the Cook Inlet and Palmer Hay Flats areas near Anchorage. Biologists and hunters first realized the extent of the lead poisoning problem in migration and wintering areas of Canada and the "Lower 48" during the 1960s. In response, the U.S. Fish and Wildlife Service gradually curtailed the use of lead shot and by 1991 lead shot was prohibited for waterfowl hunting in all 50 states.
"Preliminary sampling of birds and pond bottoms during the 1970s revealed no significant lead problems" said Chris Dau, current Wildlife Biologist at Izembek National Wildlife Refuge and former Wildlife Biologist at Yukon Delta National Wildlife Refuge (1971 to 1981). "However, the lakes we sampled had soft, muddy bottoms and lead would probably sink and not be as available to feeding waterfowl compared to lead in lakes with firmer bottoms. Lakes with firm, sandy bottoms are present in some areas of western Alaska. Birds feeding in these lakes could easily consume lead shot if it were present." Pond bottoms had not been sampled in the area where the dead eiders were found in 1992. Dau also noted that lead shot remains available in the sediments for many years and that even lead deeply imbedded in soft sediment can become available to waterfowl if the sediments are disturbed by ice action or other natural or human-caused factors.
Birds suffering from acute lead poisoning are reluctant or unable to fly or walk and often remain on the water when surrounding birds are flushed. They are weak, may have difficulty holding their heads erect, and may eventually lose their fear of people. Bright green droppings may be observed along the shoreline. In hand, these birds are often extremely thin with very little breast muscle or body fat and may have a bright green stained vent. In addition, paralysis of the digestive system may result in food being packed in the throat and esophagus. Lead shot also may be present in the gizzard. Lead-poisoned birds often have high concentrations of lead in their livers and kidneys.
The U.S. Fish and Wildlife Service would like to determine the extent of the lead poisoning problem in western Alaska. Anyone who harvests or finds dead birds exhibiting symptoms of lead poisoning is requested to freeze the carcass (or liver and kidneys) and contact the Service toll free at (800) 272-4174. All hunters are reminded that only nontoxic (steel) shot may be used to hunt waterfowl in Alaska.
-FWS-
