Condors are shot full of lead
The proof is in the data. Lead ammunition threatens the multimillion-dollar recovery program for California condors.
Many California condors have extremely high concentrations of lead and must occasionally be caught to undergo chelation therapy to remove the heavy metal from their blood. But for the past 22 years, scientists and hunting activists have argued over how this endangered species is being poisoned. Now, research posted today on ES&T’s Research ASAP website (DOI: 10.1021/es060765s) finds that hunting ammunition is the cause of lead poisoning in condors. The results may spur state regulations that force hunters to use nonlead ammunition in the condor range.
Don Smith, a professor of environmental toxicology at the University of California, Santa Cruz, and corresponding author of the study, says that years of anecdotal evidence have pointed to hunting ammunition as the source of lead in condors, but scientists lacked hard data.
“These results are a no-brainer,” he says. “The problem is that the people who need to be convinced to take action have not been convinced,” he says, referring to politicians and special interest groups that fight attempts to regulate lead ammunition.
For the study, Smith and colleagues measured the blood-lead levels of 18 free-flying condors and compared them with those of 8 condors that were raised in captivity. Whereas the captive condors had lead levels that averaged 27 ppb, the wild condors’ average blood-lead concentrations were nearly 10-fold higher at 246 ppb.
U.S. Fish & Wildlife Service, retired
The researchers then went shopping at numerous stores close to the condor range and bought bullets and shotgun shells. When they examined the lead isotope signature of the ammunition, they found that it matched the isotope signature of the lead found in the condors. Smith says that the results remove any doubt about how condors are being poisoned in the wild.
“It’s all coming from lead ammunition,” he says.
Looking back, moving forward
During the 1970s and 1980s, about half of the population of California condors disappeared. Three documented cases were due to lead poisoning. In the early 1980s, all of the remaining birds were captured and became part of a captive-breeding program. Since 1995, >140 condors have been released into the wild, and at least 4 of those have died from lead poisoning. An additional 26 condors have received emergency chelation therapy to reduce blood-lead levels.
“The bottom line is that there are a lot of bullet fragments in deer carcasses,” says Grainger Hunt, a senior scientist with the Peregrine Fund. In 2001, hunters killed well over 100,000 game animals within the condor range. When these animals are not found by hunters, they can become food for condors.
Hunt and colleagues recently published a study in which they X-rayed 33 carcasses of deer that had been killed by hunters (Wildlife Soc. Bull. 2006, 34, 167–170 [312KB PDF]). Their radiographs showed that bullets explode into dozens of tiny pieces when they enter an animal. Half of the carcasses carried at least 100 bullet fragments.
Condors also feed on the gut piles that hunters leave behind when they gut a deer before packing out the meat. Hunt examined 20 gut piles and found that 18 of them contained lead fragments.
“The condor food supply is almost completely contaminated,” says Noel Snyder, a retired biologist with the U.S. Fish & Wildlife Service. He adds that Hunt’s research [5.1MB PDF] shows that deer flesh is tainted after the animals are shot; this raises questions about human health as well. “When you look at these X-rays, you have to ask yourself, ‘Why would I eat deer meat?’”
In recent years, California has attempted to limit the use of lead ammunition in the condor range, but introduced legislation continues to get defeated. Kelly Sorenson of the Ventana Wildlife Society says that hunting groups and the National Rifle Association are resisting change but that lawsuits filed in July by environmental groups may force state legislators to act. Although it is costly, ammunition made from other metals is available.
The U.S. Fish & Wildlife Service finds that lead poisoning threatens the condors’ recovery. The agency estimates that $35–40 million has been spent on condor recovery over the past 20 years, and $22 million of that sum came from federal coffers. The federal government continues to spend $900,000 annually on the program.
Smith says that condors are just a poster species for other animals, such as golden eagles, that are also being exposed to lead from ammunition. “It’s all just highly politicized,” he says, of the whole issue. “Even though we know how to solve the problem, we do not move forward.”
