Print PageQuantitative measurements of phenology are a primary source of evidence regarding biotic responses to climate and land cover change. Phenologies of plants are routinely measured (e.g., NDVI and EVI). Both plant and animal phenologies have been assessed with direct human observations such as flowering dates, arrival dates, and egg-laying dates. While phenologies based on direct observation often have longer historical series, they also often suffer from sparse data and problems of observer bias. To our knowledge there are no widely available measures of animal phenology that are remotely sensed at high frequency over a continental spatial extent. Recent availability of continental scale mosiaced radar products from NOAA-NWS has made it possible to access unprocessed radar data for as low as 5 minute time intervals. Over the past 20 years several studies have demonstrated that weather surveillance radars have potential to quantify animal phenologies. These analyses have been very informative, but have been limited primarily to sites that are well sampled by individual WSR-88D stations and analyses have been limited to data from a few days or months of data.
Results/Conclusions
We use these mosaiced reflectivity data to describe the phenology of 358 purple martin (Progne Subis) roost locations listed for the summer of 2010. Patterns in the reflectivity data from individual roosts varied widely probably as a result of the size of the roost, distance from a WSR-88D facility, and surrounding landscape. Nonetheless, the overall seasonal pattern in reflectivity matches the expectation of increasing densities of martins at roosts through July and a declining trend in August. These findings suggest that mosiaced NEXRAD radar products have potential to provide a phenological index for animal biology across the continental US.
