Pesticide Spraying on National Wildlife Refuges Needs to Stop, Advocates Say

Green groups are urging the federal government to ban harmful agricultural chemicals on public lands set aside for vulnerable species.

You could fit all the world’s Alabama cavefish in a five-gallon bucket. About two inches long with no eyes or pigment, they are some of the rarest fish in North America. Maybe 100 remain, and they’re only known to exist in the dark, subterranean pools of a single cave in Lauderdale County, Alabama.

In 1997 the U.S. Fish and Wildlife Service (FWS) established Key Cave National Wildlife Refuge to protect habitat for the cavefish and the gray bat, both listed as endangered species. Groundwater contamination is among the biggest threats to the cavefish, and one potential source of that pollution is row-crop agriculture near the cave. “The application of pesticides to these crops may impact the fauna in Key Cave,” the FWS wrote when it listed the species as endangered in 1988. 

Even so, about one-quarter of the 1,060-acre refuge—a designated Important Bird Area that hosts several avian species in decline, such as Grasshopper Sparrows, Short-eared Owls, Loggerhead Shrikes, and Northern Bobwhites—today is used to grow crops like corn and millet. And despite the acknowledged ecological risks of pesticide contamination, those fields have in recent years been treated with glyphosate, dicamba, and other toxic agricultural chemicals that have been shown to harm wildlife. 

In 2020, refuge biologist William Gates alleged, in a complaint to the U.S. Department of the Interior’s Office of the Inspector General, that the way farming was being practiced at Key Cave violated a federal refuge-management law. Among other problems, Gates wrote that refuge officials approved pesticide use despite a lack of required buffers—strips of vegetation intended to prevent chemicals from running off of fields to sinkholes that feed into the cave. Interior has not announced any formal response to that complaint.

Key Cave is not alone. Citing concerns about refuges across the country, a pair of advocacy groups in late February formally petitioned the FWS and its parent department, Interior, to ban agricultural pesticides on refuge lands. “The use of harmful agricultural pesticides to grow commercial row crops such as corn and soybeans on national wildlife refuges—the only public lands where wildlife must come first—defeats the objectives of the Refuge System and poses a significant threat to the species that rely on these refuges and the habitats that they provide,” the Center for Biological Diversity and the Center for Food Safety argue in the petition, which also raises concerns about the health impacts on refuge workers and visitors.

All told, farmers sprayed more than 350,000 pounds of pesticides on 363,000 refuge acres in 2018, the most recent year with complete data, the groups say, citing an earlier Center for Biological Diversity report. That marked a 34 percent increase from the 270,000 acres treated in 2016.

The FWS allows private farmers to use some public refuge lands on the condition that they leave a portion of their crop unharvested—20 percent, in the case of Key Cave—as a welcome source of calories for migrating birds and other wildlife. Much of this crop production happens on land that was farmed before it was absorbed into the refuge system. The agency works with farmers to transition some farmland to native grasses and other natural habitat.

A spokesperson said the FWS is aware of the petition but declined to answer questions from Audubon.

The pesticides sprayed on wildlife refuges include controversial chemicals whose impacts on human and environmental health have come into greater focus in recent years. For example, glyphosate, the active ingredient in the widely used herbicide Roundup, has been linked to higher risk of cancer, birth defects, and a host of other health problems. In 2021, the EPA found that glyphosate is “likely to adversely affect” 1,676 federally threatened or endangered plants and animals—93 percent of all species evaluated, including 88 birds. 

Imidacloprid, just one of many insecticides in the neonicotinoid class, likely has adverse impacts on 80 percent of species evaluated, according to the EPA. Neonicotinoids have been shown to harm avian species, with one 2020 study linking their increased use to annual declines of grassland and insectivorous birds in the United States, by 4 and 3 percent a year, respectively.

The herbicide dicamba is notorious for drifting from treated fields onto neighboring lands and harming trees and other wild plants. Last year, Dale Bumpers White River National Wildlife Refuge in Arkansas reported to the EPA that drifting dicamba from outside farmland damaged 160,000 acres of its property. Yet in recent years the refuge—a major winter haven for waterfowl—approved dicamba spraying on its own farmland, the groups say, though refuge officials appear to have phased out its use by the time of its report to the EPA.

The petition calls on the FWS to immediately stop approving new pesticide use on refuges; restore a 2014 ban on genetically engineered crops and neonicotinoids on refuges, which was revoked in 2018; and begin a public rulemaking process to end all use of agricultural pesticides on wildlife refuges. It follows more than a decade of lawsuits and campaigning on the issue by the Center for Food Safety and other groups.

Their proposal has support from scientists. “There really is little justification for using insecticides and seed treatments in a wildlife reserve in my opinion,” said Christy Morrissey, a University of Saskatchewan ecotoxicologist who studies pesticides, in an email. “Dicamba and neonicotinoids have very high toxicity profiles to birds and insects even in low concentrations.” 

Gates, who retired as Key Cave biologist just after lodging his complaint, is not the only former refuge employee concerned about agricultural chemicals. Audubon spoke with a former refuge manager who, upon assuming that role a decade ago, was surprised both by how little refuge officials knew about pesticide application on the sanctuaries and by the number of chemicals in use. “The regional biologist told me that it was highly unusual for people to take this process very seriously,” says the former refuge manager, who spoke on condition that their name be withheld. They also noted that—like at Key Cave—farmers were not using required buffers to keep pesticides out of waterways. “There were many, many holes in the system.” 

Only a tiny fraction of the refuge system’s 95 million land acres is treated with pesticides, and it’s a vanishingly small slice of the nation’s 895 million acres of agricultural land. But these are no ordinary acres, wildlife advocates note. The 568 national wildlife refuges were created specifically to protect important habitat, often as stopover sites along avian migration flyways and in many cases offering access to nature near cities. They provide habitat for more than 380 threatened and endangered species and some 700 bird species. 

The relatively small scale of pesticide use in refuges is not an argument for allowing it to continue, but all the more reason to put an end to it, says Hannah Connor, senior attorney at the Center for Biological Diversity. “It’s not a huge economic driver of the refuge system, and it is truly problematic in terms of fulfilling its mission and goals,” Connor says. “That just means it should be a no-brainer to be able to look at what significant harms could befall wildlife from these practices on wildlife refuges and say: No more.”