Proceedings of the Ninth Mountain Lion Workshop - Carnivore ...

had increased to over 25% of the cougar harvest composition. This result was as they
predicted given their hypothesis that adult females were the age-sex class least vulnerable
to harvest and would be last to increase in the harvest composition following intensive
harvest. They suggested that a high proportion (over 25%) of adult females in the harvest
may be an indicator of a declining trend in a hunted population. The even greater
proportions of adult females in the 1998-2006 cougar harvest in Idaho’s Warren DAU
(33%) and Selway DAU (31%) strongly suggest that a decline has occurred in these
wilderness cougar populations due to intensive harvest. Alternatively, source
populations, such as the wilderness DAUs would be expected to have a greater proportion
of adult females than sink populations, and therefore would be more likely to have a
greater proportion of adult females represented in the harvest composition than sink
populations. Even if this explains the high adult female proportion in wilderness DAU
harvest composition, sustained high mortality of adult females (such as the 8 years of
harvest from the wilderness units, 1998-2006) will alter that population’s ability to
always function as a source. In addition, any decrease in production from prolonged
mortality of adult females may result in increased reliance of wilderness units on
immigrants from surrounding areas as fewer philopatric offspring would be available to
replace adult losses. Decreased productivity from frequent turnover of home ranges could
also contribute to a decline in the population. Unlike the adverse effects on productivity
associated with high adult female harvest, the representation of older age class male
cougars in the wilderness DAUs’ harvest composition suggests that the male component
of this population is less intensively harvested.
Management Implications
There are broader population implications derived from the recent high cougar harvest
rates in wilderness DAUs, that not only affect cougar populations and harvest within
those DAUs, but first affect surrounding areas. If Idaho wilderness DAUs no longer
function as source populations, the lack of dispersing subadults would affect adjacent
sink area cougar populations and harvest levels where high hunter harvest would no
longer be compensated for by immigration. Wilderness cougar populations would be
maintained longer than adjacent sinks, because philopatric offspring would obtain
available home ranges. These cougar populations would decline only after sustained high
mortality and decreased productivity. If wilderness cougar populations now have a
reduced capability to function as source populations, this may be one factor contributing
to declining harvest trends in Idaho.
After peaking in the late 1990s, declines in cougar harvest and livestock depredations in
Idaho and other western states suggest that on a regional scale, cougar populations have
also declined. Adaptive management depends on updating state cougar management
plans addressing and incorporating recent changes in cougar population trend such as
recent indications that across the west, cougar numbers are stable or declining. Annual
DAU harvest statistics from Idaho Department of Fish and Game mandatory carcass
checks provide the ability to detect changes in sex and age composition of the cougar
harvest. These data should be closely monitored in order to guide adjustments in
strategies to meet management objectives. To optimize source population effects from
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