Classifying the Bell and Lamar county historical records as part of the contiguous range, classifying the Tarrant and Bexar county records as natural occurrences, and assuming that undisturbed mixed--grass prairies were more than marginal habitat for the BTPD could have placed the species in >130 Texas counties.
In defining polygons within 200 m of one other to be part of the same colony, the average maximum distance at which we could hear a BTPD alarm call was estimated.
In the search for a definition of a BTPD colony, the historical megatown between Clarendon and San Angelo was considered.
First, the entire potential historical range of the BTPD in Texas was not remotely sensed.
An underlying assumption was that BTPD colonies are relatively stable over a 3-5 year period.
General conclusions about trends in the Texas BTPD population were drawn, but historical data could not be precisely compared to current data for three reasons.
Some BTPD signatures appearing as variants on 1994-97 DOQs appeared as puck and halo signatures on 2004 NAIP imagery.
The diverse emotional responses triggered by the BTPD will continue to be a factor in management efforts affecting the species, but with more landowners managing lands for wildlife, a BTPD recovery program may generate more interest.
In areas with frequent sylvatic plague outbreaks, fragmentation of BTPD complexes may benefit the BTPD, since plague is more devastating in areas with dense concentrations of BTPDs than in areas with isolated colonies (Luce 2003).
Fore gave us a unique look at BTPD colonies in the Trans-Pecos.
A ward within a colony was used to designate disjunct subpopulations in a colony existing close enough to one another to communicate vocally (King 1955, Hoogland 1995), and an element occurrence used to describe disjunct populations of BTPDs occurring within 1,000 m of one another (NatureServe 2006).
Historical records of BTPDs in Tarrant, Smith, Fayette, and Bexar Counties were classified as relocations (Cottam & Caroline 1965: Fig.