Mountain Lions of the Black Hills

50 Mountain Lions of the Black Hills

develop the value. We assumed that it was reasonable, however, because the region
was semi- isolated from other known lion populations and was relatively small, there
were few if any competitors, and the residents and visitors to the region were excited
at the presence and possibility of observing the species and thus eager to report mor-
talities. In fact, the South Dakota Department of Game, Fish and Parks regularly re-
ceived calls reporting sightings, vehicle- lion mortalities, and carcasses observed when
visitors were recreating in the Black Hills. These conditions would enhance the like-
lihood that the relationship represented the pattern displayed by the population.
This piece of information also allowed us to model population size, beginning with
the estimate generated by the South Dakota Department of Game, Fish and Parks of
about 15 mountain lions in 1996 (fig. 4.4). Considering this potential for increase and
the potential variability that could affect this rate of increase, including the initiation
of a harvest, these data indicated that a somewhat protected mountain lion popula-
tion (human- related mortality did occur during this time) could increase from about
15 individuals to more than 200 individuals in 8 to 10 years (1996–2006). Informa-
tion in support of this increase included the increase in known mountain lion
mortality, from just a few (1–2) to close to 30 per year over this time span. We were
continually finding opportunities to capture new lions in the Black Hills, estimates
of survival were greater than 80% for both adult males and females ( table 4.2), and
our preliminary estimates of population size using the captured lions in mark-
recapture analyses supported high estimates of population size. Other studies that
have documented survival of mountain lions over this time period have reported

35

30

25

20

Mortalities^15

10

5

0

1994 1996 1998 2000

Year

2002 2004 2006 2008

figure 4.3. Relationship between mountain lion mortalities and time. These data

were used to estimate rate of increase in the Black Hills population.