One in five managers of federal wildlife refuges say that they, their staff, or their families have been threatened or harassed because of conflicts over government land management policies.

This finding is from a new survey released on Thursday by Public Employees for Environmental Responsibility (PEER), which represents land managers, scientists, and other government staff.

The survey comes shortly before a second federal trial of members of an armed militia that occupied the Malheur National Wildlife Refuge in Oregon last year. Seizure of the refuge headquarters lasted more than a month. The first trial ended in October with the acquittal of seven defendants.

PEER got responses from more than 100 managers of the Fish and Wildlife Service’s National Wildlife Refuges, plus more than 350 land managers employed by the Bureau of Land Management, which controls vast tracts of the American West.

Of the wildlife managers who reported being threatened, only half said they were encouraged to report the incident. And more than 60% of wildlife managers disagreed with a statement that visitor safety is better protected now than it was five years ago.

The survey suggests that the Malheur occupation is part of a wider pattern of conflict over federal land management policies including restrictions on livestock grazing. Almost half of BLM managers said they faced threats to their safety because of resource management issues.

“Fear of attack is rooted in resource management,” PEER's executive director, Jeff Ruch, told BuzzFeed News. “It’s not drunken campers.”

One respondent to PEER’s survey feared that the acquittal of the Malheur defendants in the first trial “is going to empower more people to take over federal facilities.” Another wrote: “I regularly am afraid to go in public due to the unpopularity of the agency. If I had a different employment option I would leave.”

Through annual Freedom of Information Act requests, PEER has also tallied reported incidents of violence, threats, or harassment against federal agency employees. Not all are reported, however.