Disturbance Influences Long-Term Population Patterns in the Puerto Rican Frog, Eleutherodactylus coqui (Anura: Leptodactylidae)

Population estimates from 1987 to 1995 are reported for the terrestrial anuran, Eleutherodactylus coqui, from four long-term study plots in the Luquillo Experimental Forest of northeastern Puerto Rico. The major factor influencing population size during this time was Hurricane Hugo, which deposited much of the canopy onto the forest floor in 1989. This increase in ground-level structure was in part responsible for a six-fold increase in the number of adult frogs in 1990 and a large increase in the number of juvenile frogs in 1991. Population densities since Hurricane Hugo have been influenced by succession, with continued high densities associated with thickets of Cecropia and Heliconia. Treefalls, which are similar to hurricanes on a local scale, also were shown to influence population sizes. Years with prolonged dry periods reduced numbers of juvenile frogs, but rainfall patterns alone did not explain most population variation. Population levels of invertebrate predators were related to variation in frog numbers.