Quantifying animal phenology in the aerosphere at a continental scale using NEXRAD weather radars

Abstract

Abstract. One of the primary ecological manifestations of climate change is a shift in the timing of events in a species' annual cycle. Such phenological shifts have been documented in numerous taxa, but data for animals have been derived primarily from human observers rather than networks of instruments used for remote sensing. The potential to use the network of weather radars in the United States (NEXRAD) to remotely sense animal phenologies could advance our understanding of the spatiotemporal scaling of phenologies in relation to shifts in local and regional climate. We tested the utility of NEXRAD radar products for quantifying the phenology of the purple martin (Progne subis) at summer roost sites in the United States. We found that the maximum radar reflectivity value in the hour before local sunrise above purple martin roost sites contained a strong phenological signal of significantly increased radar reflectivity during June, July, and August 2010. The seasonal pattern in this radar signal matched our expectation of the timing of formation and dissipation of these seasonal roosts. Radar reflectivity was greater and less variable when considering roosts close to NEXRAD stations (,25 km) than when including all 358 documented roosts; there was a negative relationship between maximum reflectivity and the distance between a roost and the nearest NEXRAD. Our results suggest that: (1) mosaicked NEXRAD radar products are a valuable source of information on the phenology of bioscatter in the aerosphere; (2) citizen scientists who document the locations of roosts on the ground are providing critical information for advancing our understanding of animal phenology and aeroecology; and (3) ongoing research that examines spatiotemporal relationships among radar-derived phenologies in airborne organisms, climate, and land cover change are likely to provide further insights.

Autumn morning flights of migrant songbirds in the northeastern United States are linked to nocturnal migration and winds aloft

“…Observers recorded a total of 39,638 birds known to be nocturnal migrants in morning flight during the study period, of which we analyzed data from 15,158 individual birds following our inclusion of only species known to make redetermined morning flights. Weather Surveillance Radar and Winds Aloft Since its widespread deployment in the late 1990s in the United States, WSR-88D weather surveillance radar has emerged as an extremely useful tool for tracking bird migration over large spatial extents and at relatively coarse resolution , Chilson et al 2012a, Kelly et al 2012). The U.S. National…”

Detecting bird movements with L‐band avian radar and S‐band dual‐polarization Doppler weather radar

“…; Kelly et al. ) and migration stopover areas (Buler and Dawson ) within a range of 150 km. Weather radar with dual‐polarization capability enables the separation of signals returned from biological and meteorological scatterers and from birds and insects in the atmosphere (Zrnic and Ryzhkov ; Stepanian et al.…”

Full Issue

“…Since its widespread deployment in the late 1990s in the United States, WSR-88D weather surveillance radar has emerged as an extremely useful tool for tracking bird migration over large spatial extents and at relatively coarse resolution , Chilson et al 2012a, Kelly et al 2012). The U.S. National…”