New York State Ornithological Association For the birders and birds of the Empire State |
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Posted 6/23/16 |
Lead Poisoning a Continuing Threat to Eagles
Andy Mason, NYSOA Conservation Chair
Bald Eagle, photo by Carena Pooth The danger and evidence of lead poisoning in eagles and other scavenging birds continues in NY State, with little change in the state's attitude towards the problem. In late March, two Bald Eagles were found near a deer processing operation in Delaware County. One was dead, the second very sick—and both had high blood lead levels. The second bird had been fitted with a GPS transmitter and was treated for two months by a rehabilitator, gaining weight before being released. However, the lead had already brought on neurological damage and over the next three weeks, the bird moved no more than a few hundred yards, having lost its ability to feed. On June 15 it was recovered dead by Dep't. of Environmental Conservation in an "extremely emaciated" state.
The slow starvation and death of this bird is the latest in a spate of lead poisonings of eagles. A dead Golden Eagle with high levels of lead was found in Schoharie Co. last year after snow melt. In the winter of 2014, a Golden Eagle fitted with a transmitter disappeared near Hancock in Delaware Co. Its last known location was at a pile of feral hogs shot by federal agents with lead bullets. A dead Bald Eagle was also recovered nearby. DEC's Wildlife Pathology Unit has numerous cases of dead eagles diagnosed with lead poisoning.
These birds are just the tip of the iceberg. Most dead and dying eagles end up on the wider landscape, undiscovered and unreported. It's doubtful that even 10% are ever found. Lead poisoning may well be the leading cause of death of these iconic birds.
Lead causes neurological and organ damage in birds. In the end stages of lead poisoning, birds experience lethargy and convulsions. Lead from wounded carcasses and entrails of deer shot with lead bullets has been documented as the principal factor in the near-extinction of California Condors.
There is little doubt that ingestion of lead bullet fragments is the primary cause of lead poisoning in eagles. Most other sources of lead such as paint, gasoline, fishing sinkers and plumbing have been removed from the environment: the concentration of sickened birds near lead-killed wildlife and gut piles cannot be coincidental. There is also a significant rise in lead poisoning during hunting seasons and in areas where lead bullets are used. Studies of the isotopes, or fingerprints, of lead connect the poisoning with ammunition.
To add to the tragedy of the eagles, these deaths were avoidable. Non-toxic alternatives exist for hunters that are ballistically equivalent or superior to lead. This is not an anti-hunting issue. Most hunters are responsible and would not want their activity to endanger other wildlife and certainly not eagles. There is precedent for changing ammunition: waterfowl hunters now use non-toxic shot after lead was found to be poisoning loons and other birds.
Although regional DEC staff and the wildlife rehabilitator did all they could for the Delaware Co. bird, the agency has largely taken a hands-off attitude to the problem. Other than a few modest informational efforts, DEC has done little to address lead poisoning in wildlife and the associated threats to humans who consume venison. Even DEC's own law enforcement personnel still use lead bullets.
The Delaware-Otsego Audubon Soc. has produced a short video that tells this story through the voices of hunters and their families. It is recommended viewing for anyone concerned with the well-being of our national bird.
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