WTPD Conservation Assessment - Endangered Species & Wetlands ...

low in 1987 of 13 white-tailed prairie dogs per km 2 (33.8 per mi 2 ). In 1988, the white-tailed
prairie dog population increased and was estimated at 65 white-tailed prairie dogs per km 2
(169 per mi 2 ).
Black-footed ferret habitat surveys were conducted in the Kennedy Wash sub-complex
from 1998 to 2003 (Table 11; Figure 7). The Kennedy Wash sub-complex showed a pattern of
trend similar to that documented in Coyote Basin; the population declined slightly from 1998 to
2001, increased sharply in 2002 and declined significantly in 2003. The coefficient of variation
for Kennedy Wash was 48% (Table 12).
Snake John-- Black-footed ferret habitat surveys were completed in the Snake John subcomplex
from 2001 to 2003 (Table 11; Figure 7). White-tailed prairie dog population estimates
were similar in 2001 and 2002, but like Kennedy Wash and Coyote Basin, populations declined
significantly in 2003. The coefficient of variation for Snake John was 25% (Table 12).
Shiner Basin-- Shiner Basin was surveyed from 1997 to 2000 (Table 11; Figure 7).
White-tailed prairie dog populations declined from a high of 47,551 in 1998 to an estimated low
of 5,383 in 1999. Due to this significant decline, Shiner Basin was removed from consideration
as a black-footed ferret release site even though transecting in 2000 documented an increase in
the white-tailed prairie dog population estimate. For the 4 years of surveys, Shiner Basin had a
coefficient of variation of 91% (Table 12).
In 2002 and 2003, a low intensity survey effort (~ 60% of area sampled) was conducted
within the Shiner Basin Management Area in order to evaluate white-tailed prairie dog
population recovery (B. Zwetzig, BLM, pers. comm.). Survey results showed presence of
white-tailed prairie dogs but at extremely low densities.
Averaging white-tailed prairie dog population estimates for all four Black-footed Ferret
Management Areas surveyed in Utah from 1997-2003 showed a pattern of populations reaching
high densities with subsequent declines in both 1999 and in 2003 (Figure 7). White-tailed prairie
dog populations at all 4 Black-footed Ferret Management Areas within the Uintah Basin
fluctuated despite the short term duration in monitoring (3-7 years/site) with coefficients of
variations ranging from 25% to 91% (Table 12; Figure 7). Population estimates demonstrated
dramatic increases and decreases in numbers of white-tailed prairie dogs within a one-year
period (e.g., Kennedy Wash increased from an estimated 3,670 prairie dogs [3/ha] in 2001 to
10,282 prairie dogs [8.6/ha] in 2002 and Shiner Basin saw a decline in white-tailed prairie dogs
from 47,551 [10.99/ha] in 1998 to 5,383 in 1999 [1.76/ha]) (Table11). Because white-tailed
prairie reproduce only one time per year and produce an average of 5.64 + 0.74 embryos per
litter on the basis of uterine swellings (Bakko and Brown 1967), these oscillations in population
estimates are biologically significant. Whether these fluctuations are normal is unknown and
can not be determined with the short-term duration in sampling. Additional long-term data is
needed to evaluate trends.
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