Fagerstone, K.A. et al.: BLACK-TAILED PRAIRIE DOG COLONY DYNAMICS IN SOUTH DAKOTA OVER A 10-YEAR PERIOD

KATHLEEN A. FAGERSTONE; HOWARD P. TIETJEN; JAMES F. GLAHN; GREG L. SCHENBECK; JEAN BOURASSA: BLACK-TAILED PRAIRIE DOG COLONY DYNAMICS IN SOUTH DAKOTA OVER A 10-YEAR PERIOD.

Link: http://www.aphis.usda.gov/wildlife_damage/nwrc/publications/05pubs/fagerstone051.pdf

Zitat :

Abstract

Between 1968 and 1978, aerial photography was used to monitor distribution of blacktailed
prairie dog (Cynomys ludovicianus) colonies on a 400-square mile area in South Dakota,
including parts of Buffalo Gap National Grassland, Pine Ridge Indian Reservation, and Badlands
National Monument (now Badlands National Park). Aerial photographs were taken of the study area
in 1968 and annually from 1974 through 1978 at a scale of 1:20,000 (1968) and 1:15,840 (1974-
1978). Prairie dog colonies were identified on the photographs, outlined, and the outline transferred
to USGS topographic maps for colony size measurements. This technique reliably detected changes
in prairie dog colony numbers, size and distribution. Although there was limited use of prairie dog
rodenticides early in the study, the land area occupied by prairie dog colonies increased by
approximately 28.4% over the 10-year period. Between 1968 and 1974 area occupied by prairie dog
colonies increased from 1154 ha (1.4% of the area) to 5890 ha (7.1%). By 1978, prairie dog
colonies occupied 14023 ha (16.9% of the area). The number of colonies increased from 110 in
1968 to 344 in 1974 and 508 in 1978, with many colonies being assimilated during colony
expansion. Prairie dog colony expansion rates were significantly lower on the Badlands National
Monument (BNM) than on the Buffalo Gap National Grasslands, private lands, and Pine Ridge
Indian Reservation. The BNM is ungrazed by livestock (cattle), while most other rangelands in the
study are a grazed annually by livestock at moderate to high stocking rates. Standing vegetation
around prairie dog colonies in the National Monument was noticeably greater than around colonies
elsewhere in the study area, suggesting that vegetation impacts from annual livestock grazing
significantly increased colony expansion rates outside the BNM. Modifications to the grazing
regime may improve rangeland condition, particularly during drought years when the rangeland is
under stress, and could slow or eliminate prairie dog colony expansion.