Why is the Forest Service Destroying Critical Mule Deer Habitat?

Mule deer in Wyoming. Photo: Tom Koerner/USFWS.

These are the facts. Almost half of the Ashland Ranger District of the Custer-Gallatin National Forest in southeastern Montana has burned in recent wildfires. This has severely impacted mule deer habitat, resulting in a declining mule deer population which will continue to fall if the Forest Service goes forward with its proposed South Otter logging and burning project on 292,000 acres (456 sq. miles) of public lands.

The 1990 Ashland Deer Guidelines were developed jointly between the Forest Service and the Montana Department of Fish, Wildlife and Parks to limit logging impacts on what they note is “the most stable and important population of mule deer in southeastern Montana.” Yet, by ignoring its own scientists and arbitrarily changing existing standards, the South Otter project will destroy even more of what’s left of this vitally important mule deer habitat.

At least 60% forest cover for mule deer is recommended in the guidelines. “Cover” is defined as a forest with a minimum tree canopy cover of at least 50%. Thermal cover, to help deer survive Montana’s long, cold winters, requires a tree canopy cover of at least 70%.

At best, the South Otter project area has 35,411 acres of forest stands with a tree canopy cover of at least 40%. To get around the recommended guidelines, the Forest Service changed the definition of hiding cover for deer from 50% to 40% and “implied” that a forest with only a 10% canopy could still provide sufficient deer hiding cover.

Even under the revised definition only 12% of the project area would meet the standard. The proposed commercial logging of 26,350 acres and noncommercial removal of smaller trees on 11,165 acres could eliminate a potential 37,515 acres of deer hiding cover.

Since most, if not all, deer hiding and thermal cover within the 456 square miles of the South Otter landscape could be removed, it’s painfully obvious that maintaining science-backed habitat for “the most important mule deer population in southeast Montana” is clearly not a concern of the Custer-Gallatin National Forest managers.

The guidelines also note that juniper trees not only provide spring-summer-fall hiding cover for mule deer and their fawns, but important winter thermal cover. Despite the science, the project will burn up to 184,150 acres of mule deer habitat including an undisclosed amount of juniper trees, which the agency identified as “fuels” not wildlife habitat. The actual acreage of mule deer winter range that will be burned is unknown, as the Forest Service did not map or evaluate impacts to mule deer winter range.

Sagebrush is the primary mule deer forage on winter range. Yet the amount of sagebrush that will be burned, like the junipers, is unknown because sagebrush habitats were not mapped or evaluated by the Forest Service in the project analysis. Instead, the agency claims the sagebrush habitats may be burned for “restoration” or to create “habitat mosaics” of dead sagebrush intermingled with live sagebrush.

Mule deer fawning habitat is also not mapped or evaluated in the South Otter assessment. This is particularly critical because the agency notes that that burning could occur from mid-May through July – exactly the time period when mule deer generally give birth to their fawns and when the fawns most need low, brushy cover to hide from predators such as coyotes, mountain lions, and bears.

In conclusion, the Custer-Gallatin National Forest is now a rogue agency in the Biden administration, ignoring its own scientists, arbitrarily changing existing standards, and failing its legal mandate to responsibly manage our public lands and the wildlife they support.