C-11 Assessment for Florida Panther (Felis concolor coryi)

DeAngelis, D.L.; Gross, L.; Wu, Yegang; Bass, Oron; Fleming, D.

It is becoming recognized that understanding and predicting the viability of a population of organisms requires representing the dynamics of the population explicitly in a landscape. In addition, the viability of a small population, such as the Florida panther, may depend on the detailed structure of the population through time; age and size structure, sex ratio, physiological conditions of individuals in the population, and so fonh. As a population decreases in size, the effect of random components (demographic stochasticity) increases and becomes quite significant for predicting population size and structure. This becomes particularly significant when population sizes approach 40 individuals or less, and the individuals are distributed among several smaller, spatially separated subpopulations (Pimm 1992). In such small populations, the Florida panther being one example (in which fewer than thirty to fifty individuals may exist at any particular point in time with individuals also being distributed across several subpopulations (U.S.F.W.S., 1987)), this demographic stochasticity can affect a populations's persistence. One example of this would be if a highly skewed sex ratio occured due to sampling phenomena in offspring. The population's persistence would also be affected by a variety of external factors, such as food availability. Changes in these external factors could either magnify or decrease the effects of demographic stochasticity. Thus the relative importance of demographic stochastic effects on predicting the persistence of a local population is in general intertwined with the effects of other factors (food availability, disease prevalence, etc.). Separating out which of these is most significant requires a model capable of evaluating the interconnections between them.