A new study from the Journal of Science found that almost half of Arizona’s bald eagles suffered from some form of lead poisoning. Likewise, 37 other states were found to have eagles suffering from lead poisoning.
The main way that lead gets into the bald eagles is from their diet. Bald eagles have a tendency to be scavengers, which means many times they find themselves feeding on gut piles or carcasses left in the field by hunters. In these cases, the hunters have most likely taken game animals with lead-based ammunition. Once the lead makes its way into the bald eagle’s system it can cause all sorts of medical issues including death. However, one of the most common ailments is losing the ability to fly.
Raptor experts say the solution is simple. Hunters should not use lead-based ammunition any longer. In recent years many hunters in Arizona have been making the switch to non-lead ammo. However, many of the birds tested are showing the results of a lifetime of eating lead.
“We’ve had 80 to 90% over the last decade of hunters in the area either switching to nonlead alternatives or removing their gut piles out of the environment.” – Kenneth “Tuk” Jacobson, AZGFD Raptor Management Coordinator.
47% of the birds tested showed signs of chronic lead poisoning. Chronic poisoning means that lead was found in the birds’ bones. This means the birds have been exposed to lead over the course of a longer period of time. Likewise, 29% of birds were showing acute lead poisoning. This means lead was found in their blood and feathers. Acute lead poisoning usually means the birds have been exposed to higher concentrations of lead over a shorter period of time.
Ammo & Eagles
In Arizona specifically, big game hunters have mostly transitioned to copper bullets. However, researchers believe that most of the lead exposure is coming from bird and varmint carcasses. Many times hunters are looking to use cheaper lead-based ammo while chasing these types of animals. likewise, the majority of hunters will leave varmint carcasses in the field instead of taking the carcasses home. These then become prime food sources for the eagles, which then allows the eagles to eat the lead fragments left in the animals.