1967 it was listed as endangered by the U.S. Fish and Wildlife Service,
and was added to the state's endangered species list in 1973. As
one of the most endangered felids in the world, and due to its range
including lands under extreme development pressure, panther management
has been contentious (see Beier
et al. 2006 and Conroy
et al. 2006 for reviews).
Panther habitat has been reduced to roughly 5% of historical
levels. With each breeding unit, consisting of one male and several
females, requiring about 200 square miles (500 km2),
habitat loss and degradation due to encroaching human development
remains the primary threat to this population. Direct human-caused
mortality, primarily collisions with cars, and effects of inbreeding
also serve to reduce the likelihood of persistence for the panther.
Panthers have been isolated in southern Florida since the early
1900s. Evidence of severe inbreeding were well publicized. Due
to low population numbers and perceived threats of inbreeding,
a study in 1992 estimated that the subspecies would go extinct
within a few decades (Seal
The U.S. Fish and Wildlife Service, based on the results of three
workshops convened specifically to address the fate of the Florida
panther, translocated eight female panthers from Texas, the most
closely related population, to Florida in the mid 1900s (USFWS
1995). Five of these females produced kittens, which were
subsequently monitored as part of a program to assess success
of the program.
From 1992 onwards, researchers marked 118 purebred and 54 hybrid
kittens. Of these, 13 purebreds and 20 hybrids survived to adulthood.
Survival to adulthood was significantly higher, greater than three-fold
on average, in hybrid kittens compared to purebreds (Chi-squared
test, p<0.001). Further, adult female hybrids have lower
mortality rates than purebreds. However, the data suggest that
hybrid females do not produce more young, at a younger age, or
at shorter intervals than do purebreds, and adult male hybrids
have higher mortality rates than purebreds.
Since the augmentation effort and likely because of it, panther
numbers have rebounded from a low of 20-30 cats, to nearly 100
today, and their range has expanded.
Genetic monitoring of this population has provided insights into
the realized benefits to an inbred population post-augmentation.
The ability to track the fates of individuals in conjunction with
knowlege of their genetic composition (i.e., hybrid status) demonstrates
the value of long term genetic monitoring.