the cougar in the santa ana mountain range, california

CHAPTER 2. POPULATION DENSITY
AND STRUCTURE
Thirty-two cougars were radio-tagged
during this study (Table 2). The number of
radio-tagged animals increased in the first 3
years as our effort and the size ofthe study area
increased, and then decreased in the final 1.5
years as we discontinued capture efforts. These
changes. do not reflect changes in cougar
numbers. In all likelihood, the number of adult
cougars has not changed markedly during the 5
years of the study. Although the long-term
prognosis is for cougar numbers to decrease as
habitat is lost and fragmented, we could not
detect significant change in this 5 year period.
The sample of radio-tagged cougars
. was largest in August-September 1991; at that
time the population consisted of a minimum of
7 adult females, 3 adult males (counting M6 as
an adult who had not yet established a full-size
territory), 3 subadult males, 2 female cubs, and
2 male cubs, for a total of 10 adult and 7
juvenile cougars.
Because a relatively large fraction of
the population was radio-tagged in September
1991, we estimated cougar numbers in the
Santa Ana Mountains for that month. In these
estimates, cougars are classed as cub (from
birth until dispersing out of its mother's home
range at 18-24 months of age), subadult (from
age of dispersal until a stable home range is
established), or adult (over 24 months of age
and exhibiting a stable home range). "Juvenile"
refers collectively to cubs and subadults. We
estimate that there are about 2070 km 2 (800
mi 2 ) ofsuitable cougar habitat (Figure 1).
The true population size in September
1991 was larger than the sample of radiotagged
animals. We made no attempt to
capture or radio-collar cubs younger than 10
months ofage, and we know that at least 2 such
cubs (offspring of FlO) were alive at that time.
Ml3 (a subadult collared October 1991) and
16
another young male shot on a depredation
permit in January 1992 (see below) were also
present in September 1991 (unless they
immigrated from the Palomar Range). Tracks
indicate that at least 3 other uncollared cougars
(females or subadults) were present in easilysurveyed
areas in late 1991. Furthermore, much
of the Cleveland National Forest is not
conducive to capture efforts or track surveys,
so probably several more uncollared animals
were not detected. Finally, the regular
appearance of dispersing subadult males that
were not the offspring of radio-tagged females
indicates that there were additional adult
females.
Nonetheless, 3 lines of. evidence
suggest that a large fraction of the population
(at least those over about 20 months of age) in
the Santa Ana Mountain Range was radiotagged
in Fall 1991:
(1) Depredation incidents. During
1991, Orange County Animal Control, CDFG
wardens, or citizens relayed to our study team
about 12 reports of domestic goats or sheep
being killed by cougars. Eight cases were
promptly investigated (in other cases, the report
was received too long after the fact to be
useful). In 7 of these 8 cases, a radio-tagged
cougar was almost certainly the offending
animal, based on its proximity to the fresh
carcass. Although 1 cougar (MI2) was the
offender in 4 of the cases, the other cases
involved 1 uncollared and 3 different radiotagged
cougars.
Although 7/8 of these livestock
depredations involved radio-tagged cougars, it
would be inappropriate to conclude that 7/8 of
the entire population was radio-tagged. The
depredations all occurred in the western
foothills of the range (Santiago Canyon,
Williams Canyon, Live Oak Canyon, La Paz
Canyon, and San Onofre Canyon). The study
team was most active in these foothills
throughout the study, and may in fact have