Thought we’d completely dealt with the threat of poisonous lead in our hunting ammunition? Think again

THE BULLET FACTOR

Recent studies from North America, Europe and Australia tell us that birds are also being poisoned by lead fragments from rifle ammunition after scavenging on the remains of hunter-shot animals. That includes the viscera and other discarded portions of animals cleaned in the field, as well as wounded and lost animals that eventually die.

Take bald eagles, for example, one of North America’s most iconic birds. Study after study from across Canada and the U.S. has warned they are accumulating toxic levels of lead in their blood, liver and/or bones, with overwhelming evidence pointing to lead ammunition as the major source.

In fact, an analysis in Canada of “found-dead” birds showed that up to 15 per cent of the bald and golden eagles examined had lead levels exceeding the toxic-risk threshold. Beyond bald and golden eagles, the birds most frequently harmed by lead include vultures and other raptors, as well as the corvid family, especially ravens and magpies.

An analysis in Canada of “found-dead” birds showed that up to 15% of eagles examined had lead levels exceeding the toxic-risk threshold

John Chételat, a research scientist with Environment and Climate Change Canada (ECCC), has been studying lead exposure in scavenging birds across the country since 2018. He says the effects on birds that ingest lead include lethargy, muscle wastage, wing droop, diminished balance and coordination, increased susceptibility to diseases and parasites, poorer reproduction and, in some cases, death.

While Chételat notes that scientists know considerably less about the effects of lead exposure on furbearers, there’s no doubt they are also feeding on the carcasses of rifle-shot game. In a Saskatchewan study under the supervision of ECCC scientist Kirsty Gurney, a researcher set up a camera over the remains of white-tailed deer and found that magpies were the most common scavenger. Ravens, crows, bald eagles, great-horned owls and broad-winged hawks were also observed, along with coyotes, foxes, fishers, weasels, raccoons and even cougars. Similar studies have shown wolves and bears are also common scavengers of gut piles and discarded carcasses.

So, just how much lead contamination can be found in the carcass of a hunter-shot animal? Using sophisticated synchrotron X-ray technology, a 2022 study from the University of Saskatchewan demonstrated that thousands of tiny lead fragments, many smaller than 1/100 of a millimetre, can travel as far as 18 inches into the flesh beyond the obvious wound channel. That means there are also human ramifications to consider.

Several studies have revealed increased levels of lead in the blood of those who regularly consume wild meat

Although there are no known incidents of acute lead poisoning in humans due to eating game shot with lead-core ammunition, several studies have revealed increased levels of lead in the blood of those who regularly consume wild meat. If you’re concerned about unwittingly ingesting lead particles, the science suggests you should be trimming away a greater area around the wound channel than most of us typically do.

Another link between lead bullet fragments and scavenging birds and mammals is the vast number of ground squirrels and their relatives that are shot as agricultural pests, especially across the prairies. Invariably they’re left where they fall, with most hunters believing they’re actually doing the local hawks and owls a favour; it’s difficult to imagine how many such varmints are shot each year, and how many scavenging birds and mammals are affected as a result.

To be clear, the effect of lead ingestion varies between birds and mammals, as well as among species within each group. Several other factors, including sex and age, also influence how much lead is absorbed into the body and accumulated in tissues. Along with the amount of lead, the toxic effect is also influenced by the duration of exposure, the species’ sensitivity, and the overall health of the animal.