Proceedings of the Seventh Mountain Lion Workshop

156 DISPERSAL IN MALE PUMAS · Laundré and Hernández
estimate and they ranged from 9.0 % to 31.0
% with an average mortality rate of 20.5%.
Based on movement distances and times
presented in Logan and Sweanor (2001), we
assumed the competitive ability of a young
male puma would be at its maximum by 5
HRDs. Thus, in Eq. 1, for the competition
model, we let p(x) vary from 0.04 to 0.18
over the first 4 HRDs (x = 1 to 4) and then
after that, let it be a constant at 0.205, the
average mortality rate. The resulting curve
underestimated the number of settlements in
the second and third HRD but the pattern fit
the data relatively well in the first 4 HRDs.
In contrast it predicted more settlements in
the 5-7 HRD range and less in the 8-9 range
than what we found (Fig. 1).
For the inbreeding model, we found in
our study and in that of Logan and Sweanor
(2001), approximately 42.0 % of the young
females dispersed an average of 2 HRDs
(range = 1 to 8 HRDs, n = 14). Based on
this, a dispersing male would almost be as
likely to mate with a sister within the first 2
HRDs as in his natal home range. Also,
considering that resident females can easily
shift their home range area by at least 1
HRD during their reproductive years, we
concluded that to avoid inbreeding, a male
should disperse at least a minimum of 3
HRDs before seeking a territory.
Consequently, we set p(x) = 0.0 for x = 1 to
2 and after that, set it to the average
mortality rate of 20.5 %. As 25.0 % of the
dispersing males settled within the first 2
HRDs (Fig. 1), this model initially did not fit
the data. It also predicted a higher
occurrence of settlements in the third and
fourth HRDs than what we found. From the
fifth HRD this model patterned after the
competition model.
DISCUSSION
Regarding prediction # 1, we found
ample evidence there are high levels of
conflict between adult territorial males and
all age classes of non-territorial males
PROCEEDINGS OF THE SEVENTH MOUNTAIN LION WORKSHOP
(kittens to adults, including between fathers
and sons). These conflicts at times appear to
be over food resources but primarily are
over breeding resources. Also in almost all
cases, the older, heavier, more experienced
male wins the conflict. These data support
the competition hypothesis for dispersal
because if young males do not disperse they
will be killed by their fathers or nearby
resident males, all of whom are bigger and
more experienced.
For prediction # 2, although it can be
argued that the Florida pumas inbreed
because it is a closed population, it still
refutes the myth of a natural aversion to
inbreeding. The innate aversion to close
inbreeding is the driving force behind the
inbreeding avoidance model and, for the
model to work, should be evident under all
conditions. It is a little too anthropomorphic
to expect young male pumas to avoid
inbreeding under one situation and not
another, especially since they don’t know if
they are in Florida or Montana, i.e. they can
only gain information about the number and
distribution of potential mating opportunities
by dispersing. Relative to the New Mexico
data, based on our calculations of residency,
we predict we should find cases of fathers
not only mating with their daughters but
could do so at least twice during their
tenure. The data from Logan and Sweanor
(2001) supported this prediction, thus
refuting the inbreeding hypothesis. As
fathers mating with daughters is genetically
equivalent to sons mating with their
mothers, we see no reason why a son would
refuse to mate with his mother but then later
mate with his daughter. It might be argued
that a larger father could dominate over a
smaller unreceptive daughter. However, we
reject this argument because by the time
young males reach dispersal age, they weigh
equal to or more than their mothers
(Laundré and Hernández 2002) and upon
sexual maturity (21-27 months; Logan and