Population Dynamics of Mountain Lions 63Population Compensation and Harvest
Most studied prey (e.g., deer) populations exhibit compensation when approach-
ing carry ing capacity. This response is characterized by increased mortality owing to
decreased availability and quality of forage, which worsens the nutritional condition
of individuals in the population, reduces reproduction, and results in the population
establishing an equilibrium at some ecological carry ing capacity. Based on the popu-
lation trajectory and increased starvation that we documented, which coincided with
a perceived population saturation of mountain lions, we assumed that this population,
rather than exhibiting a classic predator- prey type of response, was responding more
to food availability and thus in a manner similar to that of a classic prey population.
If such a response was occurring, then reducing population size postsaturation would
result in a decrease in mortality and a corresponding increase in survival. This stan-
dard response would be due to the subsequent increase in prey availability resulting
from a decrease in predators, in this case, the mountain lions themselves.
Preliminary information collected on this population supported this hypothesis.
For example, vehicle mortalities accounted for 33% of mountain lion mortalities
documented prior to the initiation of harvest (2005) in the Black Hills (Fecske,
Thompson, and Jenks 2011). During the three years following the harvest, vehicle
mortality declined from 22.5% in 2005, to 16.1% in 2006, to 8.9% in 2007, while the
harvest rate on this population increased to 14% (based on harvest of radio- collared
lions) and total mortality was relatively stable at 56 ± 6 mountain lions (Fecske,
Thompson, and Jenks 2011). The nutritional condition of the lions also improved in
200
180
160
140
Total kidney fat index (%)
120100
Early Saturation Harvestfigure 4.14. Change in estimated total kidney fat index across three periods:
early, saturation, and harvest.