pestis to unaffected BTPD colonies before a widespread epizootic was initiated.
hirsuta were able to disperse between BTPD colonies potentially spreading Y.
Bureau of Land Management for granting permission to conduct research on their BTPD colonies.
Over 200 prairie species are supported by BTPDs including the endangered black-footed ferret, Mustela nigripes (Carnivora: Mustelidae) (1).
A layer of points was created from historical BTPD records, digitizing versions of historical range maps of the BTPD in Texas (Bailey 1905; Cottam & Caroline 1965; Cheatheam 1977) and merging the versions into one polygon.
The current truth layer was converted into a layer of points representing the geographic centers, or centroids, of current BTPD colonies.
Definitions of vegetative alliances and associations (NatureServe 2006) were defined to characterize the ecosystems colonized by the BTPD in Texas.
Between 2000 and 2004, occupied BTPD colonies in 73 Texas counties were ground-truthed, and reports of occupied colonies in Reeves, Irion, and Tarrant Counties were received (Fig.
Based on these results, the range of the BTPD in Texas had receded from the southern and eastern historical boundaries and from the western historical boundary in the Trans-Pecos (Fig.
BTPD advocates have used an historical baseline of 800 million animals to compare to the current population of BTPDs in Texas.
First, BTPD colonies shift on the landscape when the animals exhaust food resources in an area and then move towards fresh vegetation (King 1955, Hoogland 1995).
The methodology in this study for accumulating BTPD records was not exhaustive, so clusters of records may exist in areas not included in the historical distribution.