DNR study seeks farm chemical levels in wild deer

Minnesota deer hunters will be tapped as volunteers next month in a wildlife research project to assess levels of neonicotinoid insecticides in free-ranging deer.

The pilot study by the Department of Natural Resources (DNR) was inspired by a university research project in South Dakota that found bad effects when captive whitetails were exposed to the widely used farm chemicals. Decreased fawn survival, reduced physical activity, smaller reproductive organs and jaw abnormalities were recorded in deer that were given significantly higher concentrations of "neonics" than other deer in the South Dakota State University study.

Minnesota's inquiry is meant to measure the relative prevalence of the chemicals inside deer and will focus on deer harvested all around the state in conjunction with the firearms season that opens Nov. 9.

"We are looking for help from anybody and everybody who wants to be involved,'' said Eric Michel, DNR's newly hired deer biologist for the farmland region.

The DNR's goal is to obtain at least 800 spleens from hunter-harvested deer, equally divided in deer permit areas with low, medium, and high row crop density. The agency is supplying a sampling kit and video instructions to participating hunters. They'll learn how to recognize and remove the spleen — a large, flat, dark red stomach organ shaped like a cat's tongue.

Michel, who worked on the recent South Dakota study as a postdoctoral researcher, said the initial phase in Minnesota will be to map baseline levels of neonicotinoids in the wild herd. The toxic insect killer, widely applied to corn and soybean seeds as a coating, has become so pervasive in the environment that it might even show up in Minnesota's forested deer, Michel said.

"We're expecting to find it, but we don't know at what levels,'' he said.

"As concentrations increased, we saw decreased activity,'' researchers wrote.

Michel said the captive animal test facility in Brookings, where the research was conducted, was adjacent to corn and soybean fields. Even members of the control group of deer — those who weren't dosed with the chemicals — were found to have neonics in their systems, Michel said.

Deformities found in dosed whitetails included overbites and smaller than normal reproductive organs, the study found. The study was published earlier this year in the journal Scientific Reports. Co-author Jonathan Jenks, a professor and wildlife ecologist at SDSU, is helping out on the Minnesota study.

Neonicotinoids have received lots of scientific attention in relation to the decline of bees and other pollinators. And in Minnesota, DNR wildlife researcher Charlotte Roy recently published trail camera observations of pheasants, other birds, raccoons and other mammals eating crop seeds dropped on farm fields in simulated spills or in simulated plantings where the seeds weren't completely covered by dirt.

Her report said ingestion of a small number of coated corn or soybean seeds can be lethal to small birds. She observed over a dozen species of birds and mammals feeding on the spills. She wrote that the presence of seeds on soil surfaces should be considered in pesticide risk assessments.