Wildlife Affected by Lead

Lead poisoning in wildlife is well documented and has been known to be a factor in waterfowl deaths for over a century. Today, most lead poisoning in wildlife is from animals ingesting lead pellets left over from spent shot, fishing sinkers, and jigs. Dabbling and diving waterfowl such as teal, loons, mergansers, and goldeneye are particularly susceptible because of their feeding habits and environment.

Bald Eagle suffering from acute lead toxicity. (Photographer Unknown)

Other species are subject to lead poisoning as well. Mourning Dove, American Woodcock, and other upland birds may ingest lead-contaminated invertebrates or lead shot from soil, mistaking it for food or grit. Wild turkeys, quail, and pheasants have been affected. Lead poisoning has also been noted in small mammals and fish can accumulate concentrations of lead by absorption.

Raptors may scavenge or prey upon birds, mammals, or fish that have been exposed to lead, resulting in the risk of secondary lead poisoning. This became strikingly evident in the summer of 2000 when five of  the captively-bred California Condors reintroduced into the Vermilion Cliffs area of Arizona died from lead-poisoning. It is believed they ingested lead shot from a mule deer carcass.

Any raptor species that forages on game animals is at risk of secondary poisoning including Golden and Bald Eagles, California Condors, and accipiters such as Cooper's Hawks and Northern Goshawks. Digestive acids wear down the leaden material which is then absorbed into body tissues. When lead enters the circulatory system, it mimics the movement of calcium. It becomes stored in the bones and some may be excreted into the feces via the bile. Eventually, concentrations may reach toxic levels causing a variety of problems which often end in death.

Lead poisoned Golden Eagle, unable to use legs, eventually euthanized. (Courtesy of the Montana Raptor Conservation Center)

Ingested lead remains in a raptor's gizzard and is eventually absorbed into the blood stream. In waterfowl, a dose of one pellet can result in anemia while lethal doses of five or more pellets can cause heart attacks or paralysis that lead to death. In many birds, sub-lethal dosages present a variety of symptoms. These include immune suppression, reproductive impairment, weight loss, wing droop, diarrhea, and tissue damage. Many of the sub-lethal problems result in death due to reduced physical performance, susceptibility to disease and infection, and increased predation.

In most cases, it is impossible to treat affected wildlife for lead poisoning. There are treatments available if the animal is in the early stages of lead poisoning. However, the majority of animals found suffering from lead toxicity are in the advanced stages and are not likely to survive.