WTPD Conservation Assessment - Endangered Species & Wetlands ...

Predicted Range Model
Sixteen percent of the white-tailed prairie dog gross range and 13% of the predicted range
occurs in Utah (Table 1, Figure 12). Three percent of the white-tailed prairie dog gross range in
Utah is located on agricultural lands, while 0.2% of the predicted range is impacted by urban
areas (Tables 6 and 7). Twenty percent of both gross range and predicted range is located on
private land within the State (Table 14). Within Utah, 11,187 oil wells are currently located in
the gross range and 8,835 oil wells are located in the predicted range.
Limiting Factors
Disease -- Sylvatic plague monitoring has been conducted by the USGS in Coyote Basin
and Kennedy Wash since 2000 (Biggins 2003a). Blood samples have been collected from
white-tailed prairie dogs, Peromyscus maniculatus and P. truei. This monitoring is in response
to the use of Deltamethrin as a tool to study the ecology of plague as well as examine its
effectiveness at controlling flea populations. Plague was detected in Kennedy Wash in 2001 and
2002 and in Coyote Basin in 2002 (Biggins 2001, 2003a). Serological test results in 2002 found
2 sero-positive white-tailed prairie dogs in Coyote Basin (109 sampled) and one in Kennedy
Wash (45 sampled) (Biggins 2003a). Plague was not detected at either site in 2003 (D. Biggins,
USGS, pers. comm.). Though low levels of plague have been detected in Coyote Basin and
Kennedy Wash, surveys do not suggest an epizootic level of the disease.
Changing plant communities and drought -- Within much of the white-tailed prairie dog
habitat in Utah, cheatgrass establishment over native perennial grasses and forbs has been
extensive (Boschen 1986, B. Maxfield, UDWR, pers. comm.). Cheatgrass competes for
moisture with other more desirable species due to its winter and early spring growth (Whitson et
al. 2000). After cheatgrass reaches maturity in early summer, it provides little nutrition and
moisture either above or below ground for herbivores (Stubbendieck et al. 1997). This may
hinder the ability of white-tailed prairie dogs to build sufficient fat reserves, resulting in
decreased overwinter survival, subsequent reduced reproductive rates and increased rates of
parasitism. Utah prairie dog colony extinction rates have been found to increase as the number
of native, locally occurring plant species declined (Ritchie 1999).
Ongoing drought conditions in Utah over the past 5 years may have negatively impacted
white-tailed prairie dog populations. In the past few years, white-tailed prairie dogs have been
observed foraging on plant species during the early summer months that they usually do not use
until early to late fall (B. Zwetzig, BLM, pers. comm.). These species include Gardner’s
saltbush and cactus. They have also been seen foraging throughout the summer months on ants.
The changes in observed foraging activities may indicate that preferred species are not available
for consumption and that they are instead relying on alternative sources for nutritional needs. In
addition, white-tailed prairie dogs have been observed emerging throughout the winter months
possibly indicating inadequate body condition to maintain hibernation (P. Schnurr, CDOW; B.
Zwetzig, BLM, pers. comm.). During the hibernation phase, mass losses of 26-30% have been
recorded for yearling white-tailed prairie dogs (Cooke 1993). Thus an inability of white-tailed
prairie dogs to build sufficient mass to compensate for overwinter losses is detrimental to
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