Nutritional Ecol ogy of Mountain Lions 97fairly uniformly distributed across the region (although not mule deer versus white-
tailed deer), elk and other large prey tend toward more clumped distributions. There-
fore, you might expect some lions to become better able to capture these clumped
prey, because the lions’ territories and home ranges overlap those of these less distrib-
uted and thus more rare prey species. Because the lions are more likely to encounter
these species, they would gain experience in attempting capture, especially if they be-
gan by capturing young of the species (e.g., elk calves). If so, then certain lions would
potentially focus their prey capture skills on deer, others on elk, and others on bighorn
sheep, just to name the top prey available to lions in the Black Hills. In fact, some have
argued that this proclivity for specific prey could mean that lions would eradicate some
herds of bighorn sheep that had been released as part of restoration proj ects (Festa-
Bianchet et al. 2006). At times we observed kills of elk calves and lambs of bighorn
sheep, which would be about the same size as deer and thus would be more susceptible
to predation once lions had become adept at capturing deer. However, adult female and
male elk are considerably larger than deer, so the risk of injury during capture attempts
would be much higher. Furthermore, other studies of lion populations have docu-
mented deaths of lions from injuries obtained during such capture attempts (Lindzey
1987). Therefore, the question came to mind, Why risk injury attacking adult elk when
you could more easily capture deer and when, since deer are more prevalent, you
have more experience capturing deer than those large, rare elk?
Chronic wasting disease could have come back into play with these larger kills,
because lions living in the southern portions of the region would have had diseased elk
and deer available to them. I received reports that hunters in Custer State Park (imme-
diately north of Wind Cave National Park) had observed multiple dead elk carcasses
in an area where there had been sightings of mountain lions. Hunters at the time were
implicating lions in these deaths; they thought the predators were engaging in “surplus”
killing. But why risk injury killing more than one elk, when it would take a considerable
amount of time to consume the first one killed? We hypothesized that these sightings
were more likely related to disease deaths, in this case CWD, and that the lions would
be expected to select sick or diseased prey at higher proportions than healthy prey
(Smith 2014), even though evidence for this phenomenon has been mixed (Barber-
Meyer, White, and Mech 2007; Krumm et al. 2009).
We had the opportunity to evaluate the se lection of diseased elk by two adult moun-
tain lions (one male, one female) that used portions of Wind Cave National Park (Smith
2014). From January 2011 to June 2012, we documented prey remains at 31 GPS cluster
sites for the two lions in the park. For these two lions, prey items consisted of deer, tur-
key, coyote, one scavenged bison (Bison bison), and 20 elk carcasses. There were a total
of 14 mountain lion– killed elk (7 by the male, 7 by the female) with tissue samples
available to test for CWD (testing was conducted by Wind Cave National Park person-
nel). Six elk kills were not tested for the disease, but two of them were elk calves, which
would not be expected to test positive. The average age of these kills was 9.8 years, and