Proceedings of the Seventh Mountain Lion Workshop

152 DISPERSAL IN MALE PUMAS · Laundré and Hernández
Under each model, specific predictions
can be made to test their application to male
pumas. Under the competition model, we
predict that there should be physical
conflicts between adult males/kittens
(infanticide), adult males/juveniles,
including father/son, and adult male/adult
male. Older, more experience males should
win these conflicts and competitive ability
of dispersers should increase with age and
thus, the longer time and further distance
they are from their home area (Sweanor
1990). Thus, another prediction for this
model is that dispersal distances should
reflect their competitive ability, i.e. few
males will establish territories close to their
natal home range. Under the inbreeding
avoidance model, we predict less physical
conflicts (young males leave on their own),
no inbreeding between fathers and
daughters, which is genetically equivalent to
sons mating with their mothers, and no
males establishing territories within a
minimum of 2 home range diameters of their
natal home range (Sweanor 1990). We
attempted to test these predictions with data
from our study in southern
Idaho/northwestern Utah and published data
from a variety of other studies of pumas.
We recognize that it is often difficult to
obtain good dispersal data on a species such
as the puma but combining the data from the
various studies that exist should provide us
the best opportunity to examine possible
causes of dispersal in male pumas.
METHODS
To test the predictions made, we used a
combination of data from our long-term
study of pumas and published data on other
puma studies. In some of these studies,
pumas were protected from hunting while in
the others they were exposed to sport
harvest. However, in the case of the
protected populations, the protection
extended only to the limits of the study
areas, which ranged in size from ≈ 500 to
PROCEEDINGS OF THE SEVENTH MOUNTAIN LION WORKSHOP
2,000 km 2 or a maximum diameter of 50
km. Because in all the studies, most young
male pumas dispersed to outside of the
designated study areas, we consider that
pumas were dispersing under unprotected
conditions. Consequently, we did not
subdivide the studies into protected and
unprotected populations.
Our study of a harvested puma
population was conducted in southeastern
Idaho and northwestern Utah. The study
area was approximately 2,000 km 2 and
consisted of 5 small mountain ranges
(approximately 1,000 km 2 total area)
separated by valleys where human activity
predominated. Over 16 years, we conducted
intensive capture efforts each winter and
with the help of trained dogs, we captured
and marked approximately 150 pumas. We
documented male-male conflicts based upon
our intensive field efforts. We obtained
dispersal data of young radio collared male
pumas primarily from hunter returns. We
measured straight-line dispersal distance
from the center of the natal home range to
the point of harvest. In addition to our data,
we searched the published literature for
accounts of male-male conflicts, incidences
of inbreeding, and estimates of dispersal
distances. For male conflicts, we considered
3 levels of conflict, adult male/kitten
(infanticide), adult male/subadult male, and
adult male/adult male. Incidences of
inbreeding were obtained via field
observations and, in some cases, genetic
testing.
For dispersal, we expressed male
dispersal distances from natal home ranges
in multiples of the average male home range
diameter (HRD) (Waser 1985). We
calculated HRDs for each study assuming a
circular home range (Sweanor et al. 2000).
We then estimated the cross study HRD
average and then divided dispersal distances
of each study by the cross study mean HRD.
Although we assumed the mean of the