Nutritional Ecol ogy of Mountain Lions 93Fall River County near Hot Springs, South Dakota, also tested positive for the disease.
In 2002 Wind Cave National Park personnel documented CWD in a Rocky Mountain
elk within the park boundary and became concerned about distribution of the disease
within resident populations of deer as well as in the elk population. In November 2002
a suspected 5- year- old female elk in Wind Cave National Park was euthanized and
tested; this animal also was positive for CWD (Wind Cave National Park press release,
November 18, 2002). By 2005 Schuler (2006) estimated that the prevalence rate for
the disease in mule deer averaged about 9% and could have been as high as 15%. Since
both mountain lions and CWD colonized the southern Black Hills initially, and since
diseased prey likely represented easy kills, they could have contributed to the lions’
transition from preying upon porcupine and domestic species to preying upon deer-
and elk- sized prey.
Behavioral characteristics of deer and other cervids that are associated with CWD
include the loss of fear of humans (and likely of predators), ner vous ness, and hyper-
excitability (Schuler 2006). Furthermore, there is some indication that diseased
individuals are shunned by healthy members of their species. If so, then diseased in-
dividuals would be located farther away from other individuals, and because of reduced
vigilance and ner vous ness, they would be vulnerable to attack by lions. In fact, statis-
tical modeling conducted by Schuler (2006) indicated that deer with CWD had a higher
probability of being killed by a predator (in this case coyotes and mountain lions) than
deer that were negative for CWD, even though coyotes were more likely than lions to
leave tissues for disease sampling ( table 6.6).
Overall, as the population approached saturation, we did see more deer in stomachs
of necropsied lion carcasses. In addition, the South Dakota Department of Game, Fish
and Parks provided funding specifically to evaluate mountain lion feeding patterns.
We therefore modified our methods to collect data specifically on kill sites and to
Table 6.6. Cause- specific mortalities of deer at Wind Cave National
Park, South Dakota, February 2003 to December 2005, and number
of samples testable and nontestable for CWDCauseTestable
(CWD
positive) Nontestable
Coyotea 3 (1) 2
Mountain lion 1 (0) 4
Vehicle collision 4 (1) 0
Hunting outside park 4 (0) 1
Lethal removal in park 5 (3) 0
Unknown 3 (2) 3
Sourcea : Schuler 2006.
Coyotes were more likely (60%) than mountain lions (20%) to leave tissues
for disease testing.