Population Dynamics of Mountain Lions 49and Sweanor 2001). That was the case with our work. Although it can be difficult to
maintain radio- collared mountain lions for long periods because of transmitter fail-
ure, interactions with other lions that affect the integrity of the collar material, deaths
from natu ral and human- derived causes, and movement out of the Black Hills, some
lions occupy rather predictable home ranges where they have access to adequate prey
and cover habitat and are relatively far from human disturbance. These cats are likely
to remain alive and well, and they may only need to be recollared every few years to
remain active participants in research studies (see fig. 3.1). This was the case when
we began evaluating survival, movements, and dispersal of mountain lions.
Studies had been conducted on these topics (survival, movements, and dispersal)
previously (Ross and Jalkotzy 1992; Lindzey et al. 1994; Lambert et al. 2006), and most
results indicated that lions generally had similar survival and home range sizes across
regions, likely owing to the elaborate territorial system of the species (land tenure sys-
tem) (Hornocker 1970; Seidensticker et al. 1973 [but see Pierce, Bleich, and Bowyer
2000; and Elbroch et al. 2016]). However, the Black Hills was somewhat isolated from
other lion populations, and the habitats surrounding the Black Hills were almost moon-
like (e.g., open prairies and few trees of a size that could be climbed or used for cover)
to mountain lions raised in ponderosa pine habitat; such conditions might modify how
this population used its environment. Questions that arose included these: Does in-
creased population size affect territory and home range size? Does the relatively small
size of the ecoregion force lions to disperse more often than in other populations?
Along with continuing to capture and affix transmitters to lions in our original
focal area, the southern Black Hills, we began attempting to find and mark lions
throughout the central and northern regions of the Black Hills. In addition, we trans-
ferred all carcasses that we accumulated to SDSU for necropsy. Using these carcasses,
we documented the animals’ condition, using kidney fat and prey consumed. We
did, however, also notice that the number of carcasses was increasing with time
(fig. 4.3). We hypothesized that the rate of increase in carcasses was in some way cor-
related with the increase in population size and thus could be used to estimate the
intrinsic rate of increase of the population.
By means of a log transformation and regression analy sis, I used the resulting slope
of this relationship to estimate the intrinsic rate of increase of mountain lions, which
was 0.33 and just a bit higher (but not significantly so, based on the standard error of
the estimate) than the highest intrinsic rate of increase (0.28) presented for an increas-
ing population of lions in New Mexico (Logan and Sweaner 2000). This rate trans-
lates to an innate ability for mountain lions to increase population size by up to 39%
per year, and although this high rate might be specific to the Black Hills and due to
the smorgasbord of prey available (from mountain goats to deer to small mammals
and even birds, such as turkeys [Meleagris gallopavo]) to lions, it was still within the
realm of rates considered reasonable for the species. Nevertheless, the estimate was
just an index to the rate of increase for this population, because of the data used to