The ban on lead used in fishing equipment – sinkers and jigs – is again under discussion in the Legislative Assembly.

Lead poisons any animal that ingests it. The impetus this year was the discovery of dead trumpeter swans allegedly swallowing lost lead fishing gear while feeding.

Lead pellets, leftovers from when lead shot was legal for waterfowl hunting, is also a problem. Lead shot was banned nationwide in 1991. However, lead remains at the bottom of lakes and never breaks down.

Loons swallow old pellets while searching for necessary small stones in their gizzards to aid digestion. Swans can ingest lead fishing gear or shotgun pellets when foraging on the bottom of lakes.

Eagles and other raptors eat deer killed but not found or guts left behind when a deer is dressed. They eat game birds that have been killed or injured but not recovered. All of them may contain lead fragments.

I was curious about how lead hurts swans, loons, eagles and other raptors. My questions, addressed to the Raptor Center at the University of Minnesota, were specific to eagles.

“Lead is one of the most frustrating things we deal with here,” said Dr Victoria Hall, executive director of the center.

More than 85% of eagles admitted to the center have a detectable level of lead in their bodies, she said. Up to 25 to 30% of these eagles will have a level of toxic lead that will kill them, she said.

It only takes a lump of lead the size of a grain of rice to kill a bird. There are several types of lead bullets. Some can shatter into dozens of fragments upon entering a deer.

The fragments, sometimes too small to see, can penetrate up to 18 inches from the path of the bullet, according to research from the Minnesota DNR. There is no known safe level of exposure.

“We see eagles arriving with food still in their stomachs, in excellent body condition, and the damage caused by lead to their nervous system is already too severe to save them, even when we try to treat them,” Hall said.

The biology of this was explained by Dr. Dana Franzen-Klein, who is the chief veterinarian at the Raptor Center.

“When birds eat lead, the soft metal enters the very acidic stomach where the metal dissolves and is absorbed into the bloodstream,” she said.

The lead causes the red blood cells to burst, making the bird anemic.

Lead damages the bird’s nervous system, causing irreversible brain damage.

It causes permanent neurological damage. The bird will begin to have convulsions, appear extremely depressed, and be unable to walk or breathe normally; it will gasp.

The lead will travel to the kidneys and heart of the bird and damage it. Heart damage can be permanent, so even if clinic staff help the bird overcome toxicity, it will never again have the stamina it needs to fly freely again, Franzen-Klein said.

“If a bird comes in with a toxic lead level and is already showing severe outward signs of lead toxicity, then the best we can do is humanely euthanize it,” she said.

How long does it take for an eagle with lead in its system, not found and untreated, to die in the wild?

“It can range from a few hours to a day or two,” Franzen-Klein said.

A very small piece of lead can produce symptoms within hours.

If exposed to a smaller amount of lead, the bird can take days or weeks to die, Franzen-Klein said.

“Eagles exposed to very high doses of lead often have no chance of a successful treatment no matter what we try; the damage is rapid and permanent.

“For lower doses of lead, if the bird is found a few hours or a day or two after exposure, we might have a chance of saving it,” Franzen-Klein said.

“Eagles are more sensitive to lead toxicity than swans and some other species,” she said.

Swans are sometimes able to recover from a level of lead in the blood that will kill an eagle. The treatment is slightly different for each of these species.

From 2010 to 2020, the Raptor Center admitted 202 eagles where lead was one of the health concerns. When lead was the only problem, 24 birds recovered and were released into the wild.

Due to similar problems with condors, California banned all lead ammunition in 1993. The use of lead ammunition in federal wildlife shelters was banned under the Obama administration. This ban was overturned by the Trump administration.

The only restriction on lead ammunition in effect here is the Federal Waterfowl Act. Minnesota has no regulations on the use of lead to hunt other animals. There are no rules regarding lead used in fishing.

There are non-toxic substitutes in all cases. Use is voluntary.

Bird watcher Jim Williams can be reached at [email protected]