New research shows how fragments of lead rifle bullets are poisoning eagles, bears and other wildlife that scavenge carcasses left by hunters. (Video: Assignment Earth


>>  Wildlife biologist Brian Bedrossian is waiting for ravens and eagles to take the bait.  As soon as the birds land on an animal carcass that he’s placed in the field, he remotely launches a net.  On this day, he catches two ravens and an eagle.  Trapping wild birds allows him to test their blood.  What he’s looking for is a problem more commonly associated with people.  He even runs the birds’ blood through a machine designed to track lead exposure in humans.  One sample registers so high, it would probably send a person to the hospital.

>>  Rather shocking.  I think this is – this may be one of the highest lead levels I’ve ever seen in a raven.

>>  Since lead doesn’t stay in the blood long, researchers can pinpoint the time of exposure.

>>  With a lead level of greater than 65 micrograms per deciliter, there is zero doubt that that bird has ingested lead within the past two weeks.

>>  That coincides with hunting season.  Here in Northwestern Wyoming, eagles and ravens commonly feed on the remains of elk left by hunters.  New findings in this study and others are raising concerns about the lead rifle bullets that many hunters use.  Another study, north of Yellowstone National Park, found high lead levels in grizzly bears, which also scavenge carcasses left by hunters.

>>  A lot of lead fragments in that one.

>>  Researchers are just now discovering how widely these bullets can scatter bits of lead through game meat.  The toxic fragments show up as white specks in X-rays of animals that have been shot.  Many are so small you could eat them without realizing it.

>>  If this one were left out in a field, if we didn’t pull it out, it definitely could have poisoned a number of birds.

>>  High exposure to lead can cause neurological damage in humans and wildlife.  Eagles with lead poisoning can experience loss of balance, gasping, tremors, and trouble flying, and can lead to starvation and death.  But there is a simple solution.  Hunters can keep lead out of the field and their meat by switching to copper bullets that don't contain lead.

>>  I think in general we just have to be more careful about how we use lead and look for alternatives that can replace lead that aren’t toxic.

For Assignment Earth, I’m Gary Strieker.

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