ARMY ANT POPULATION-DYNAMICS - THE EFFECTS OF HABITAT QUALITY AND RESERVE SIZE ON POPULATION-SIZE AND TIME TO EXTINCTION

A simple deterministic model is used to examine the effects of habitat size and quality upon the sizes and chances of extinction of isolated populations of a species of neotropical army ant, Eciton burchelli. T he results of the model suggest that equilibrium population size is in fluenced more by habitat size than quality. Similarly, expected extinc tion times increase exponentially with habitat size but depend on qual ity only through its minor effects upon the equilibrium population siz e. Such effects may be crucial from a conservation point of view, howe ver, because of the strong dependence of extinction probabilities on e quilibrium population size. Density-independent effects in the form of queen senescence also have strong effects on expected extinction time s but not on equilibrium population size. The results are used to pred ict which of several islands and peninsulas in and around Gatun Lake, Panama, have a high probability of still being populated by E. burchel li after their isolation from the surrounding tropical rain forest.