Gas wells trap deer during spring migration

It’s as if the deer showed up for an exciting feast, but stumbled, waved it away and let the best food go stale.

This is essentially a new discovery from a joint study by the US Geological Survey (USGS) and the University of Wyoming, which quantified how mule deer lack of feed if energy development violates them migration corridors.

“Mul deer are known for how accurately they match their movements to spring greens, so this result was particularly impressive,” says lead author Ellen Aikens, a UW Ph.D. graduate who now works at South Dakota State’s Joint Division of Fish and Wildlife Research. “Gas wells made them slip away from the best food of the year.’

The document “Development of industrial energy divides ungulates migration from green wave» is published today (Thursday) in Ecology of nature and evolution.

Every spring in the American West, mule deer migrate to follow the greens of plants that sprout at different elevations. Biologists call this “surfing the green wave.” Mule deer rely on this surfing behavior to find the youngest and most nutritious plants to allow them to recover from the winter and gain fat for the next lean season.

However, a new study shows how development is disrupting deer movements, causing deer to lose their ability to match foraging with the wave of spring’s most nutritious plants.

The 14-year study followed a herd of migratory mule deer that winter in sagebrush pools and summer in the Sierra Madre Mountains, about 15 miles southwest of Rollins.

During the study period, dozens of new coalbed methane wells were drilled in the middle of the existing deer corridor. Long-term movement data made it possible to compare the impact of expansion on deer movement before and after.

Previous research by the team has detailed how mule deer behavior has changed in response to new gas wells, causing them to detour, speed through well sites and stop less often to forage.

For the new study, the team analyzed deer movements — along with daily changes in spring foliage estimated from remote satellite images — to measure how well the deer traveled along the corridor, upstream and downstream of the power generation, and over a period of 14 years. annual period.

“The movements of the deer in response to the gas field were unmistakable,” Aikens says.

As the intensity of development increased over time, the deer began to “hold” when they reached the natural gas wells. They suspended their spring migration and missed the wave of green vegetation, depriving themselves of their best food resources at a crucial time of the year.

Overall, the wells resulted in a 38.65 percent reduction in green wave surfing over time.

There was no evidence that mule deer had acclimated to development and the associated increase in human presence, truck traffic, and noise. Small-scale and large-scale developments have equally changed the behavior of surfing on green waves.

The research will help wildlife managers understand how intact corridors need to be to maintain their ecological functionality. In this case, deer could still move through the gas field, but the key function of the migration corridor—tracking the green wave all the way through at the ideal stage of plant growth—was lost.

The finding is important because if migrating ungulates are unable to maximize foraging, it will reduce the overall benefits of migration, which is often the most profitable strategy for ungulates as diverse as mule deer in Wyoming, caribou in the Arctic, or pronghorn antelope behind the rains throughout the area. the African plains. The study is a cautionary tale that provides a clear mechanism for how development within corridors can reduce the benefits of migratory behavior, ultimately leading to loss of migration and population declines in severely impacted landscapes.

The researchers hope that these findings will help provide a way forward for sustaining the mule deer migration.

“The impacts are clear, but also point to conservation solutions that will allow us to maintain viable migrations for generations to come,” says co-author Matt Kaufman of the USGS Wyoming Cooperative Fish and Wildlife Research Division at the UW. “Once migrations are mapped, development can be planned to minimize disruption to migrating herds, whether in Wyoming, the American West, or where landscapes are rapidly changing.”

Additional co-authors on the paper include Teal Wyckoff of The Nature Conservancy and Hall Sawyer of Western EcoSystems Technology Inc.

The work is timely, as numerous state and federal initiatives have been implemented in the US over the past five years to map and mitigate migration corridors. In Wyoming, state wildlife managers have long sought to map and preserve migratory corridors, now guided by state policy. Efforts are underway worldwide to map global ungulate migrations for use in conservation and development planning.

“This new study provides the most compelling evidence yet that efforts to minimize development in migration corridors will benefit their long-term conservation in the face of changing landscapes,” says Kaufman.