Dr. Bray Links

Sunday, June 4, 2017

California Condors and Lead Poisoning

How does lead poisoning happen in condors and other scavenging birds anyway? Scavengers eat many different types of animals, some of which are shot with lead projectiles. Animals either left behind in the field, such as ground squirrels and coyotes, or animals shot and unable to be recovered, contain lead fragments left behind in the shot animal. Animals shot with shotgun pellets are also available to scavengers as well as waterfowl depending on where the shooting takes place. Condors and other wildlife often ingest large chunks of flesh and sometimes bone and cannot distinguish between a tiny lead fragment from a bullet versus a pebble for example. Once ingested, the digestive system interacts with the lead bullet which leaches the lead into the bloodstream of the animal that ingested it. Lead in blood rises dramatically after ingestion of a lead object and within days the animals feels the effects. Lead poisoning is an awful way to die because it paralyzes the digestive system often killing the animal slowly through starvation. If any of this is new to you or you are skeptical, please do your own research and start by reviewing the links, video, etc. at the bottom of this page.

The literature linking lead poisoning in condors to lead from spent ammunition is strong. In fact, we have contributed some of it. But what really convinces us is the direct evidence we have seen during our 15 years of managing the central California Condor population. As a recent example, a 10 year-old male condor (#318, Figure 1) died in November 2012 after ingesting a lead .22 caliber bullet, presumably while feeding on a carcass. The bird was found in San Benito County barely alive and unable to feed or use its legs to stand. Despite valiant efforts, veterinarians could not save him. Cause of death, through necropsy, was determined to be lead toxicosis. A radiograph showed multiple metal fragments and a bullet-shaped object in the digestive tract (Figure 2). The object was removed and determined to be a .22 caliber lead bullet (Figure 3). 


No comments:

Post a Comment

Note: Only a member of this blog may post a comment.