Are peccaries contributing to the amphibian and reptile declines at La Selva Biological Station, Costa Rica

Background/Question/Methods

Populations of the highly diverse leaf litter-dwelling frogs and lizards within the nature reserve at
La Selva Biological Station in Costa Rica have declined by 75% over the last 35 years. The causes
of these worrisome declines are unknown, but likely include synergistic effects of multiple stressors
that include infectious diseases and changes to the quality and/or quantity of the leaf litter habitat.
One factor that could affect the leaf litter habitat is an apparent increase in the size of the collared
peccary (Pecari tajacu) population within the La Selva reserve. Peccaries are medium-sized, pig-
like, terrestrial mammals that travel in large groups and can create disturbances in the leaf litter and
soil. Peccaries may affect the breakdown of leaf litter, the cycling of nutrients, and the availability
of food and habitat for animals that live in the leaf litter. I tested the hypothesis that peccaries are
contributing to the ongoing leaf litter amphibian and reptile declines at La Selva by comparing the
abundances of amphibians and reptiles inside fenced peccary exclusion plots to paired, open control
plots. If peccaries were contributing to the amphibian and reptile declines at La Selva, I expected
to find fewer amphibians and reptiles in the control plots where peccaries had access.

Results/Conclusions

I encountered significantly more individual amphibians and reptiles on control plots than inside peccary
exclusion plots (t = -3.408, P = 0.000653). My results indicate that peccaries are not one of the
stressors contributing to the amphibian and reptile declines at La Selva.