Dr. Anna Chalfoun and a student research assistant popped the cork on a bottle of champagne, celebrating the first recapture of a songbird fitted with a backpack geolocator they deployed a year earlier.

“We didn’t know we were going to be able to do this. It was so exciting, in a nerdy way!” Chalfoun said, recounting the celebratory memory.

However, Chalfoun’s documentation of reasons why songbirds and other avian wildlife are declining in the sagebrush sea isn’t really a reason to celebrate. Chalfoun has spent the past 20 years studying diversity in what many call “drive-through country,” or a “barren wasteland.” She is currently the assistant leader of the Wyoming Cooperative Fish and Wildlife Unit and associate professor at the University of Wyoming.

Yet, what she has discovered is both proof of the value in plant and wildlife diversity in the sagebrush steppe — of which Wyoming has more of than any other state in the U.S. and encompasses hundreds of flora and fauna species — and that human intervention in the sensitive habitat negatively affects many iconic songbirds and other avian species of the West.

She discovered through her decades of research that the success of songbird species’ nests decline the closer they are to tracts that have been regenerated after drilling operations have ended and restoration is completed without striving to match native plant life of surrounding habitats.

Surprisingly, the smallest of predators — which are artificially encouraged by nonnative plant growth — are responsible for the most harm to songbirds who choose to live in the harsh conditions of the sagebrush steppe.

You might think of nest predators like coyotes, badgers, hawks or even ravens. However, Chalfoun has found the biggest offenders in nest predation are deer mice.

Deer mice are omnivores, eating whatever is available. When you study their relationships to songbirds, you find out these harmless looking brown mice — one of the most abundant mammals in America — are unthinkably evil varmints.

Deer mice not only eat eggs and live chicks, they also will maim chicks in a nest to make sure they can’t fledge (leave the nest) so the mice can come back for more servings of fresh, tender chicks from the same nest. Unfortunately, attempts to reseed encourages more of these bird-eating mice.

Oil and gas operators are required to reseed areas after they come in and they clear pipelines or well pads. Oftentimes, these areas are adjacent to quality sagebrush steppe habitat, Chalfoun said during a Lunchtime Lecture at the Draper Natural History Museum’s Coe auditorium; part of the Buffalo Bill Center of the West.

“It just depends on which seeds [operators] are able to get in a particular year,” she said, pointing out the problem. “These reseeded areas actually can comprise a fairly large proportion of these landscapes.”

Deer mice flourish in these reseeded areas, finding nourishment in the nonnative plant species common which means there is a mob of mice looking for scrambled eggs or juicy chicks for breakfast, lunch and dinner.

“More than 350 wildlife species depend on the sagebrush ecosystem, as well as people,” The National Audubon Society said in a recent press release. “Reaching 14 states, sagebrush country is a vital bird habitat, but only half of it is currently left and new demands continue to be placed on it.”

Chalfoun, who has a doctorate in wildlife biology, not only researches the migration of various songbirds, like the Brewer’s sparrow, but also the travels of deer mice in areas reseeded with the nonnative plants available to extractive energy operators. She follows the birds’ migration through geolocators and uses fluorescent powder to track captured mice. They release the mice during the day and then head back to the site at night to measure and track their adventures. Not only were there more mice in areas reseeded by operators, but they are willing to travel further than mice in areas of only native plants. Some mice traveled a quarter-mile in a night — a huge hike for the species and twice as far as mice not reared among nonnative plants in some places, she said.

“The abundance of most of these rodent nest predators also increased in abundance along that same surface disturbance gradient associated with development. And just to cross our T’s, and dot our I’s here and bring it full circle, more rodents in an area indeed is correlated with decreased nest survival,” Chalfoun said.

The adverse effects of planting nonnative species adjacent to native plants not only hurts the makeup of songbirds in the sagebrush steppe, but it might also affect Wyoming’s second largest industry.

“Tourism in Wyoming is the second largest economy. And birding in the U.S. is a multi-billion dollar economy, which is kind of mind blowing. So people do care about all wildlife in Wyoming and beyond,” she said. “It’s important for us to think about being wise stewards to facilitate multiple uses of our lands.”

Looking to help solve the issue, Chalfoun and her team decided to see if they could trap mice coming from the reseeded areas, hoping to see a reduction in nest predation. Unfortunately, the study only found that mice would move back into the areas faster than they could trap them. The other thing that Chalfoun thinks could be “really great” is if operators could put more thought and investment into improvements into restoration efforts, “instead of just being happy with OK, we reseeded.”

Next Lunchtime Lecture

Discover how pollinator habitat restoration, planting for pollinators, and native bee conservation can support both healthy ecosystems and food systems. In this Lunchtime Expedition called Flowers, Bees, and Supporting Pollinators in a Changing World, Dr. Laura Burkle, professor of Ecology at Montana State University, will explore the critical relationships between flowering plants and their pollinators — especially native bees on June 5 at noon.

Drawing from her research in the Greater Yellowstone Ecosystem, Burkle will explain how specific flowering plants impact bee populations and how you can apply these insights to support pollinators in your own yard or in large-scale restoration projects. Burkle teaches in the Department of Ecology at Montana State University in Bozeman. Her research focuses on plant-pollinator interactions and how environmental changes — including wildfire, climate shifts, and chemical exposure — impact pollinator communities. Across the Rocky Mountain West, she investigates ways to conserve and restore native bees and their habitats.