P. A. Burrowes, R. L. Joglar and D. E. Green, Potential causes for
amphibian declines in Puerto Rico, Herpetologica, 2004, 60, 141–154.
Abstract:
We monitored 11 populations of eight species of Eleutherodactylus in Puerto Rico from 1989
through 2001. We determined relative abundance of active frogs along transects established in the Caribbean
National Forest (El Yunque), Carite Forest, San Lorenzo, and in the vicinity of San Juan. Three species
(Eleutherodactylus karlschmidti, E. jasperi, and E. eneidae) are presumed to be extinct and eight populations
of six different species of endemic Eleutherodactylus are significantly declining at elevations above 400 m. Of
the many suspected causes of amphibian declines around the world, we focused on climate change and
disease. Temperature and precipitation data from 1970–2000 were analyzed to determine the general pattern
of oscillations and deviations that could be correlated with amphibian declines. We examined a total of 106
tissues taken from museum specimens collected from 1961–1978 and from live frogs in 2000. We found
chytrid fungi in two species collected at El Yunque as early as 1976, this is the first report of chytrid fungus in
the Caribbean. Analysis of weather data indicates a significant warming trend and an association between years
with extended periods of drought and the decline of amphibians in Puerto Rico. The 1970’s and 1990’s, which
represent the periods of amphibian extirpations and declines, were significantly drier than average. We suggest
a possible synergistic interaction between drought and the pathological effect of the chytrid fungus on
amphibian populations.