LARGE-SCAI.E MAPPING OF PURPLE MARTIN PRE-MIGRATORY ROOSTS USING WSR-88D WEATHER SURVEILLANCE RADAR

--Recent advances in remote sensing technologies allow researchers to inventory and study bird populations at large spatial scales. We used National Weather Service WSR88D weather surveillance radar images, acquired from the Internet, to detect and map the locations of Purple Martin (Profine subis) pre-migratory roosts across the eastern United States. Purple Martins form a distinctive ring or annulus on radar during pre-dawn departures from roosts, allowing mapping of roost sites based on this signature. Overall, we identified 33 roost sites from 13 states. Although most roosts were confined to the southeastern United States, sites as far north as Missouri and Kentucky, and as far west as central Texas and Oklahoma were detected. Seventy-three percent (24/33) of roosts were clearly associated with large bodies of water such as lakes and rivers. We found that using Internet-acquired radar images for bird studies had limitations when compared with direct acquisition of images from WSR-88D radar stations or through contracts with WSR-88D product providers. However, the increased expertise and financial investment associated with these methods make Internet-acquired radar data an attractive alternative for rapid assessment of roost locations and dynamics over large geographical areas. MAPAS A LARGA ESCALA DE LOS DORMIDEROS PRE-MIGRATORIOS DE PROGNE SUBIS UTILIZANDO RADARES WSR-88D PARA EL MONITOREO DEL CLIMA Sinopsis. --Los avances rectentes en la tecnologia de monitoreo a distancia permite que los investigadores hagan inventarios y estudien poblaciones de aves en escalas espaciales grandes. Utilizamos las imfgenes de radar de monitoreo del clima con sistema WRS-88D producidas por el Servicio Nacional de Meterorologia y adquiridas por el Internet para detectar y localizar en mapas los dormideros premigratorios de Progne subis a trav6s del este de los Estados Unidos de Norteam6rica. Esta especie produce un anillo cistintivo en el radar durante las salidas pre-amanecer desde los dormideros, permitiendo poner en mapas los dormideros basfndose en esta serial. En total, identificamos 33 fireas de dormidero en 13 estados. Aunque la mayoha de los dormideros se hallaban en el sereste de la naci6n, se detectaron localidades tan al norte como Missouri y Kentucky, y tan al oeste como Oklahoma y el centro de Texas. Setenta y tres porciento (24/33) de los dormideros fueron claramente asociados con largos cuerpos de agua tales como rios y lagos. Notamos que utilizar las imfgenes de radar adquiridas del Internet para estudios omitol6gicos tenia limitaciones al compararias con imagenes directamente adquiridas de estaciones de radar WSR-88D o via contratos con los proveedores de productos WSR-88D. Sin embargo, la experiencia necesaria y las inversiones financieras asociadas con estos m6todos hacen que los datos de radar adquiridos via internet sean una alternative atractiva para la identificaci6n rfpida de las localidades de dormideros y de sus dinfmicas a trav6s de fireas geogrfficamente grandes. The ability to inventory and study animal populations at various spatial and temporal scales is essential for effective conservation and management strategies. Methods of population monitoring are expanding to address concerns about biodiversity and landscape patterns of habitat fragmentation (Dunning et al. 1992, Maurer 1994, May 1994). This shift in • Current address: Department of Forest Resources, Clemson University, Clemson, South Carolina