Occupancy and probability of detection of the introduced population of Eleutherodactylus coqui in Turrialba, Costa Rica

Abstract

The Puerto Rican Common coqui frog (Eleutherodactylus coqui) has a long history as an invasive species in places such as Hawaii. Since its introduction in Costa Rica, scarce information is available to understand why and how the habitat in the Turrialba town is suitable for the species. Our goal was to analyze the habitat selection of E. coqui to identify if there are key habitat features that explained its success there. We measured 9 site variables that may affect the habitat selection of E. coqui in 92 survey units of 10 m radius distributed over a 500 m radius from its introduction point.  We registered the presence/pseudo-absence data of E. coqui and environmental variables in each survey unit during eight surveys. We ran occupancy models to determine the influence of the variables on the habitat selection and to estimate its detection probability. We found that sites near the introduction point, containing abundant vegetation, bromeliads, and palms have a higher probability to be occupied by E. coqui. The habitat selection in Costa Rica shares characteristics with the populations of Puerto Rico and Hawaii. But, unlike the case in Hawaii, in Costa Rica this species has maintained a limited dispersal because the potentially higher biotic resistance, as well a sedentary behavior. However, the microhabitat conditions used by E. coqui in the study site are common throughout the country. Therefore, active management in new populations and environmental education programs to avoid human transportation of the species is critical to reduce its dispersal.