Michael A. Alexander, CDC, NOAA, Boulder, CO
John K. Eischeid, CIRES, University of Colorado, Boulder, CO,


We explore the relationship between amphibian declines and climate variations in four regions Colorado, Puerto Rico; Costa Rica/Panama, and northeast Queensland, Australia using two data sets: "reanalysis" and area-averaged station data. Reanalysis merges observations from satellites, weather balloons, airplanes, etc., with output from a weather forecast model, while station data consists of temperature and precipitation measured using conventional means. In general, conditions tended to be drier than normal in all four regions around the time when amphibian populations declined. Temperatures were near normal in North America when the amphibians declined occurred while Central America was 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 amphibian declines, but reanalysis did not show such a clear temperature signal. Though declines occurred while the temperature and precipitation anomalies in some of the regions were large and of extended duration, the anomalies were not definitely 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 studies have noted that the declines appear to propagate from northwest-to-southeast from Costa Rica to Panama and from southeast-to-northwest in Queensland, Australia. The mean direction of the near surface winds, obtained from reanalysis, tended to parallel the path of amphibian declines from July-October in Central America and from May-July in Australia. However, the wind direction is highly variable and the propagation rate of amphibian declines is much slower than the mean wind speed. Thus, if winds are involved in the waves of amphibian declines, it is likely to be part of a complex process.