Population Declines of Mountain Coqui (Eleutherodactylus portoricensis) in the Cordillera Central of Puerto Rico

Abstract

The Mountain Coqui (Eleutherodactylus portoricensis) is a frog endemic to montane rainforests in the Cordillera Central and Luquillo Mountains of Puerto Rico. Classified as endangered by the IUCN Red List and as vulnerable by the Department of Natural and Environmental Resources of Puerto Rico, this species has undergone considerable decline in the Luquillo Mountains. To evaluate the population status of E. portoricensis across its entire range, we conducted ~87 hours of surveys at 18 historical localities and 25 additional localities that we considered suitable for this species. We generated occupancy models to estimate the probability of occurrence at surveyed sites and to identify geographic and climatic factors affecting site occupancy. We also constructed a suitability map to visualize population status in relation to the presence of land cover at elevations where the species has been documented, and determined the dates when populations were last detected at historical localities. Eleutherodactylus portoricensis was detected at 14 of 43 localities, including 10 of 18 historical localities, but it was not detected at any localities west of Aibonito (western Cordillera Central). Occupancy models estimated the probability of occurrence for localities in the western Cordillera Central as zero. Site occupancy was positively associated with montane cloud forest, and negatively associated with the western Cordillera Central, maximum temperature, and precipitation seasonality. The suitability map suggests that declines have occurred despite the presence of suitable habitat. We suggest upgrading the extinction risk of E. portoricensis and potentially developing a captive breeding program for this species.

Keywords: Cordillera Central; Eleutherodactylus portoricensis; Mountain Coqui; Puerto Rico; decline; extirpation; population status.

Figure 1

A Mountain Coqui (Eleutherodactylus portoricensis) at El Yunque National Forest, Puerto Rico. (Photographed by Alejandro Ríos-Franceschi).

Figure 2

A suitability map for Eleutherodactylus portoricensis generated in IDRISI Kilimanjaro. Dark areas represent potentially suitable habitat; red circles depict localities that were surveyed during the summers of 2007, 2008, 2010–2013 but E. portoricensis was not detected; and yellow circles depict localities where it was detected during the same time period. Blue shading depicts the approximate distribution of montane cloud forest, which was positively associated with site occupancy by E. portoricensis (Tables 3 and 4).