Document: ANA-3-69-47

Comparative effects of Gunnison's prairie dogs and banner-tailed kangaroo rats on plants and grasshoppers in a semi-arid grassland.

DAVIDSON, A.D.*, D.C.LIGHTFOOT and J.R.GOSZ

University of New Mexico, Albuquerque, NM 87131, U.S.A ¹

Abstract:
Prairie dogs and banner-tailed kangaroo rats are keystone species in semi-arid grasslands. Their burrowing and foraging activities are known to change the species composition and structure of grassland communities. In the American Southwest where the geographic distributions of prairie dogs and banner-tailed kangaroo rats overlap, the relative effects of their activities on grassland ecosystems are unknown. Previous research has examined the impacts of black-tailed prairie dogs on vegetation and soils, yet little is known of the effects of Gunnison's prairie dogs on soils, vegetation, or other animals. Some research has examined the influences of banner-tailed kangaroo rats on soils and vegetation, but not of their interactive effects with prairie dogs on soils, plants, and other animals. As the importance of prairie dogs to semi-arid grassland ecosystems is becoming recognized, and efforts are being made to restore prairie dog populations, information on their ecological roles is needed. The goals of this study are to determine the influences of Gunnison's prairie dogs and banner-tailed kangaroo rats on soil disturbance, and plant and grasshopper communities in a semi-arid grassland. Our research is being conducted at the Sevilleta National Wildlife Refuge in New Mexico where banner-tailed kangaroo rats and a recently expanding colony of Gunnison's prairie dogs coexist. Our initial results demonstrate that Gunnison's prairie dogs and banner-tailed kangaroo rats create different patterns of soil disturbance patches associated with their mounds, and have different effects on plant and grasshopper species compositions, abundance, and distributions. Prairie dogs construct many small burrow mounds (~0.5 m diameter). As a result, they create more diffuse, less intense local disturbance patches on the landscape, and their impacts tend to be more widespread. Banner-tailed kangaroo rats create large (~1-2 m diameter) burrow mounds, causing larger, more intense localized disturbance patches. As the colony expands, we will continue to monitor the influences of these animals on the grassland community.

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This abstract is being presented at: 2:45 PM in session:
Oral Session #51: Disturbance Ecology: Harvesting, Grazing and Roads.