The federal government in 1991 banned the use of lead shot for migratory game birds such as ducks, and South Dakota’s ban for waterfowl hunting began before that. But South Dakota still allows use of lead shot on private land when hunting upland game birds, such as pheasants and grouse.
While many studies were conducted in past decades about lead poisoning in waterfowl, there had been minimal scientific data collection and analysis regarding ingestion of lead pellets by pheasants. South Dakota has become the nation’s top state for pheasant hunting.
Consequently, the biologists’ work at the 160-acre test site in Lyman County potentially could have importance beyond the state’s borders. The first-year results were presented Friday to the state Game, Fish and Parks Commission.
“That’s a pretty big step we’re taking here, a pretty big study,” Jeff Olson of Rapid City, the commission’s chairman, said.
Travis Runia, the division’s senior biologist for upland game, said there will be another round of research this year, possibly at the same farm, which hosts paid hunting for wild birds, but isn’t a commercial preserve.
He said the study also probably should expand to look at a preserve, where birds often are pen-raised and released into the wild shortly before a paid hunting party’s reservation.
Many pheasant hunters still prefer lead shot because of perceptions that its shooting characteristics are favorable in comparison to nontoxic shot, such as steel or other metals more expensive than lead.
There also is a popular belief that lead shot wears less on barrels of older shotguns, which often are family heirlooms that are part of the annual pheasant hunting traditions. Many models of older shotguns have been discontinued by choice or by manufacturers closing.
The study at the Lyman County farm began by taking soil samples from 338 test locations across much of the 160 acres before the hunting season and then repeating at the same spots afterward.
A special tool was designed and constructed to skim about one-third of an inch of soil from an area about one-half of a square yard. The samples were separately bagged and separately washed through a sieve designed to capture any shot pellets that were No. 8 in size or larger.
They also collected hunter-harvested birds on the survey site and took the gizzards of every bird shot on the entire farm that same day. The gizzards were wrapped, put on cardboard trays and X-rayed at a local veterinarian office.
The soil results showed 41 of the 338 preseason samples had at least one lead pellet, but about three-quarters of the samples that came from within tree belts had pellets, Runia said. Only one steel pellet was found among the samples.
Overall, they found about 10,000 pellets per hectare, but about 78,000 pellets per hectare were in the tree belts, which Runia described as high.
The post-season samples are still being analyzed, he said.
The gizzard inspections involved 339 roosters and 12 had pellets.
“The true prevalence out there is about 3 to 6 percent,” Runia said.
Of the 115 roosters taken from the tree belts, eight had pellets.
Most of the birds had ingested only one or two pellets, but one had ingested nine and hadn’t yet died from poisoning.
“That is quite an exposure to lead and still be living yet,” he said.
Based on what’s found this year and possibly in 2013, a determination will be made whether to conduct further research, such as dose-response studies to see whether ingesting lead pellets influences reproduction and survival.