Population Dynamics of Mountain Lions 53Mountain lion kittens can be born in any month of the year, but there is a peak in
the Black Hills (Jansen 2011; fig. 4.8). A birth pulse occurs from June to August
(Jansen and Jenks 2012), but an in ter est ing finding from our work was that the sur-
vival of kittens born within the birth pulse was similar to the survival of those born
outside the pulse. In fact, one litter born in December survived to dispersal age.
Mean body mass for male (n = 34) and female (n = 40) kittens at 1 week of age was
1.2 kg (2.7 lbs.) and 1.1 kg (2.5 lbs.), respectively (Jansen and Jenks 2012). Between
2005 and 2009, we documented 31 litters that were born to females with whom we
had recorded evidence of previous nursing. The birth timing period was narrower
for females that had not previously nursed cubs (n = 11), and these females gave birth
mostly in July (n = 6) as well as in June and August (n = 3). However, litters born after
the peak of prey births (June–July) had heavier weights and dispersed at an older age,
suggesting there was a benefit to these kittens because they were older and more
experienced when they separated from their mothers (Jansen and Jenks 2012). Birth
timing for females that had had previous litters (n = 20) were more dispersed through-
out the year. This variation in birth timing likely occurs for older females because of
kitten mortalities. After a female loses a litter, dependent upon prey availability, she
figure 4.6. Injuries received during a territorial dispute between two mountain lions.
Photo by Dan Thompson.