930 Conservation Biology, Pages 930–942 Volume 15, No. 4, August 2001 Climate Variability in Regions of Amphibian Declines MICHAEL A. ALEXANDER* AND JON K. EISCHEID Climate Diagnostics Center, National Oceanic and Atmospheric Administration–Cooperative Institute for Research in Environmental Sciences, Mail Code RCDC1, 325 Broadway, Boulder, CO 80305–3328, U.S.A. Abstract: We explored the relationship between amphibian declines and climate variations in Colorado (U.S.A.), Puerto Rico, Costa Rica–Panama, and Queensland (Australia) through two sources of data: output from the National Center for Environmental Prediction “reanalysis system” and area-averaged station data. The reanalysis system merges observations from airplanes, land stations, satellites, ships, and weather bal- loons with output from a weather-forecast model to create global fields of atmospheric variables. Station data consisted of temperature and precipitation measured with thermometers and rain gauges at fixed locations. Temperatures were near normal in Colorado when the amphibian declines occurred in the 1970s, whereas in Central America temperatures were warmer than normal, especially during the dry season. The station data from Puerto Rico and Australia indicated that temperatures were above normal during the period of am- phibian declines, but reanalysis did not show such a clear temperature signal. Although declines occurred while the temperature and precipitation anomalies in some of the regions were large and of extended dura- tion, the anomalies were not beyond the range of normal variability. Thus, unusual climate, as measured by regional estimates of temperature and precipitation, is unlikely to be the direct cause of amphibian declines, but it may have indirectly contributed to them. Previous researchers have noted that the declines appear to have propagated from northwest to southeast from Costa Rica to Panama and from southeast to northwest in Queensland, Australia. Wind has the potential to transport pathogens that cause amphibian mortality. The mean direction of the near-surface winds tended to parallel the path of amphibian declines from July–Octo- ber in Central America and from May–July in Australia. The wind direction was highly variable, however, and the propagation rate of amphibian declines was much slower than the mean wind speed. In addition, the most likely pathogen is a chytrid fungus that does not produce desiccation-resistant spores. Thus, if wind is involved in the propagation of amphibian declines, it is through a complex set of processes. Variabilidad Climática en Regiones de Declinaciones de Anfibios Resumen: Exploramos la relación entre las declinaciones de anfibios y las variaciones climáticas en Colo- rado, E.U.A., Puerto Rico, Costa RicaPanamá y Queensland, Australia por medio de dos fuentes de infor- mación: resultados “sistema de reanálisis” del Centro Nacional de Predicción Ambiental y datos de estaciones área-promedio. El sistema de reanálisis combina observaciones de aeroplanos, estaciones terrestres, satélites, barcos y globos climatológicos, con resultados de un modelo de predicción climatológica para crear campos globales de variables atmosféricas. Los datos de estaciones fueron de temperatura y precipitación medidos con termómetros y pluviómetros en localidades fijas. Las temperaturas fueron casi normales en Colorado cuando ocurrieron las declinaciones en la década de 1970, mientras que las temperaturas en Centro América fueron mayores a lo normal, especialmente durante la época de sequía. Los datos de estaciones en Puerto Rico y Australia indicaron que la temperatura fue mayor a la normal durante el período de decli- nación de anfibios, pero un nuevo análisis no mostró una señal de temperatura tan clara. Aunque las declina- ciones ocurrieron mientras las anomalías de temperatura y precipitación fueron grandes y de duración pro- longada en algunas de las regiones, las anomalías no rebasaron el rango de variabilidad normal. Por lo tanto, es poco probable que el clima inusual, medido por estimaciones regionales de temperatura y precipit- ación, sea la causa directa de las declinaciones de anfibios, pero pudo haber contribuido indirectamente a el- las. Investigaciones previas notan que las declinaciones parecen haberse propagado de noroeste a sureste de *email maa@cdc.noaa.gov Paper submitted April 5, 2000; revised manuscript accepted January 31, 2001.