Effects of Energy Development on Pygmy Rabbits
Photo of pygmy rabbit
Pygmy rabbits are sagebrush-obligate species. They rely on sagebrush for both food and cover, and typically occur in association with relatively tall, dense stands of big sagebrush on deep, friable soils.

Project Partners

Bureau of Land Management

Wyoming Game and Fish Department

Wyoming Natural Diversity Database

The Nature Conservancy

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Pygmy Rabbits and Energy Development

The pygmy rabbit belongs to a unique community of animals that depend on sagebrush habitats of the interior American West. By digging underground burrows, pygmy rabbits aerate the soil and recycle nutrients, and their burrows provide refuges for many vertebrate and invertebrate animals. Pygmy rabbits also serve as important prey for birds and mammals.Sagebrush habitat has been reduced by half since European settlement, and much of what remains has been fragmented by development and degraded by invasions of non-native plants and altered wildfire patterns. This has created concern about pygmy rabbit population trends. Given the extent of current and potential future energy development in the WLCI region, conservation planners seek information about what makes high-quality pygmy rabbit habitats, where those habitats are located, and how energy development affects the amount and quality of habitat. 

 

Key Findings

  • Existing models classified pygmy rabbit habitat more accurately in undeveloped areas than in developed areas. Habitat classification success declined steeply in gas fields where road density exceeded 5 kilometers per square kilometer.
  • Pygmy rabbit numbers and presence drop sharply even at very low levels (1–2% of the area) of development in gas fields.
  • Buried utilities, gas well pads, disturbed areas adjacent to well pads, and well pad access roads had the strongest negative relationship with pygmy rabbit presence and abundance.

Study Objectives

  • To assess the impact of various levels of gas field development on differences in pygmy rabbit habitat quality and occupancy

 

Graph of probability of pygmy rabbits being present on gas fields as a function of increasing gas field infrastructure

Probability of pygmy rabbits being present on gas fields as a function of increasing percentage of area covered by gas field infrastructure elements. (Right click to enlarge)

Are Pygmy Rabbits Affected by Gas Fields?
 
We surveyed 120 plots across four gas fields, with plots distributed across the density gradient of gas well pads on each field. In a 1 km radius around the center of each plot, we measured the area covered by each of 10 gas field infrastructure elements and by shrub cover using 2012 National Agriculture Imagery Program imagery. We then modeled the relationship between gas field elements, pygmy rabbit presence, and two indices of pygmy rabbit abundance. Gas field infrastructure elements—specifically buried utility corridors and a complex of gas well pads, adjacent disturbed areas, and well pad access roads—were negatively correlated with pygmy rabbit presence and abundance indices, with sharp declines apparent after approximately 2% of the area consisted of gas field infrastructure.
 
 
Photo of gas well and supporting infrastructure
Photo of biologist searching under sagebrush for signs of pygmy rabbit occupancy.
Photo of pygmy rabbit hiding under sagebrush plant

Energy development can fragment and degrade sagebrush habitat needed by pygmy rabbits. Buried utilities, gas well pads, disturbed areas adjacent to well pads, and well pad access roads had a negative relationship with pygmy rabbit presence and abundance.

USGS field technicians looking for pygmy rabbits or signs of recent pygmy rabbit occupancy (fresh fecal pellets or tracks, occupied burrows) to document where in southwestern Wyoming pygmy rabbits occur and the characteristics of occupied habitats.

A juvenile pygmy rabbit hides under a big sagebrush plant.