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| California Condor. Wingspan ~10 feet |
California condors have been endangered for many decades, due to shooting and chemical toxicity. Now they face a new toxicity threat: lead. Like vultures, condors eat already-dead animals. Some of those animals have been killed by shooters, with the lead shot still inside their bodies.
Studies have now found that condors are dying at an alarming rate from lead toxicity.
HERE is a good article on it. From the article:
The impact of lead poisoning on the condor population has long been debated, but a study published this week in the Proceedings of the National Academy of Sciences provides some clarity. It shows that many condors are suffering the effects of lead poisoning, suggesting the population will continue to struggle as long as lead ammunition remains in use.
Researchers compiled the results of over 1,100 blood samples taken from 150 California condors between 1997 and 2010. The US Centers for Disease Control and Prevention recommends that children with blood lead levels above 450 ng/ml undergo treatment, and this is roughly the level at which the condors are taken in for treatment as well. About 20 percent of the birds sampled each year exceeded this level, and 48 percent of individuals living in the wild exceeded it at some point during the 14-year period. Blood lead levels as high as 6,100 ng/ml were seen.
Because blood samples only provide a snapshot of lead levels, the group also analyzed feathers from 18 condors. The concentration of lead in each segment of the feather depends on the concentration in the body at the time that segment formed. That means that each feather records a few months of exposure history. From comparisons of the most recent segment to blood levels, they were able to estimate blood lead levels over the duration of the feather.
The feathers showed that after ingesting lead, the birds’ blood concentrations exceeded 450 ng/ml for about a month. Unsurprisingly, blood samples often miss the peak lead concentrations, which were 1.4x to 14.4x higher. About 34 percent of the average feather history was higher than the level at which the condors are treated.
The Center for Biological Diversity just sent out a notice, urging their supporters to contact their legislators to put pressure on the gun industry to move away from lead shot.
Of course, the tons of lead shot into our environment each year don't just affect condors. They affect all wildlife... and us. I grew up in Arkansas, where duck hunting is very popular. Duck hunters routinely hunted in rice patties. Rice is a major crop in Arkansas, and they exported a large amount of their rice to Asian markets (believe it or not). Unfortunately, the level of lead in the rice, from all that duck hunting, exceeded safe limits for those Asian countries, who then banned purchase of the rice. Of course, us Americans were still eating it. (I don't know how long the ban lasted or if it is still in effect).
HERE is a report put out by the Arizona Game and Fish Department, reviewing the danger of lead poisoning to California condors and giving information on non-lead bullet sources. As the report details:
Biologists have documented over 300 instances of lead exposure in condors since testing began in 1999, with 45 to 95 percent of the condor population testing positive for lead exposure each year. ...
Although there may be other sources of lead, a scientific study funded by the Arizona Game and Fish Department has identified lead from spent ammunition as the major source of lead in condors. Background lead from the environment does not appear to be a factor. An additional study has determined that condor lead exposure rates are highest during the fall hunting season in northern Arizona. This study also concluded that during this same time, condors spend forage heavily on the Kaibab Plateau. The Arizona Game and Fish Department is committed to reducing the amount of lead available to condors by encouraging sportsmen to take lead reduction actions when hunting in condor range.
Condors incidentally ingest lead bullet fragments and shot remaining in game carcasses and gut piles. Fragments from lead bullets or lead shot have been found within the digestive tracts of condors 22 times in Arizona. Lead bullets fragment into hundreds of pieces before they exit a game such as a deer or coyote. Since condors are group feeders, and only one or two lead fragments or pellets can cause lead toxicity, one animal carcass or gut pile containing lead fragments or lead shot has the potential to poison several condors.
The report lists sources for non-lead ammo, and makes recommendations about minimizing effects, such as removing carcasses from access to condors.
Of course, I'm sure the NRA will label this as "junk science" and urge legislators to ignore completely. What's a few dead condors (out of only around 200 left in the wild) compared to gun industry profits and tradition?
