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1 August 2002 SPACE USE, MIGRATORY CONNECTIVITY, AND POPULATION SEGREGATION AMONG WILLETS BREEDING IN THEWESTERN GREAT BASIN
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Abstract

Western Willets (Catoptrophorus semipalmatus inornatus) were banded (n = 146 breeding adults and chicks) and radio-marked (n = 68 adults) at three western Great Basin wetland complexes to determine inter- and intraseasonal space use and movement patterns (primarily in 1998 and 1999). Birds were then tracked to overwintering sites where migratory connectivity and local movements were documented. Willets arrived synchronously at breeding sites during mid-April and spent less than 12 weeks in the Great Basin. There were no movements to other sites in the Great Basin during the breeding or postbreeding season. However, most breeding birds moved locally on a daily basis from upland nest sites to wetland foraging sites. The mean distance breeding birds were detected from nests did not differ between sexes or between members of a pair, although these distances were greater among postbreeding than breeding birds. Home-range estimates did not differ significantly between paired males and females during breeding or postbreeding. However, female home ranges were larger following breeding than during breeding. Shortly after chicks fledged, adult Willets left the Great Basin for locations primarily at coastal and estuarine sites in the San Francisco Bay area. Limited data revealed little among-site movements once Willets arrived at the coast, and birds appeared to be site faithful in subsequent winters. Winter sites of western Great Basin Willets differed from those used by birds from other areas in the subspecies' range, suggesting another subspecies or distinct population segment may exist. This study illustrates the importance of understanding movements and space use throughout the annual cycle in conservation planning.

Uso del Espacio, Conectividad Migratoria y Segregación Poblacional entre Catoptrophorus semipalmatus que se Reproducen en el Great Basin Occidental

Resumen. Un total de 146 individuos reproductivos y polluelos de Catoptrophorus semipalmatus inornatus fueron anillados y 68 marcados con radio transmisores en tres complejos de humedales del Great Basin occidental para determinar patrones inter- e intraestacionales en el uso del espacio y los movimientos, principalmente en 1998 y 1999. Las aves fueron seguidas mediante radio telemetría hasta sus áreas de invernada, donde se documentaron la conectividad migratoria y los movimientos locales. Las aves arribaron sincrónicamente a sus sitios reproductivos a mediados de abril, donde permanecieron menos de 12 semanas. No hubo movimientos hacia otros sitios del Great Basin durante la estación reproductiva o post-reproductiva. Sin embargo, muchas aves se movieron a diario localmente desde sitios de anidación en zonas altas hasta sitios de forrajeo en humedales. La distancia media entre las aves y sus nidos no difirió entre sexos ni entre miembros de una pareja, aunque estas distancias fueron mayores entre aves post-reproductivas que entre aves que estaban reproduciéndose. Los rangos de hogar no difirieron significativamente entre machos y hembras de una misma pareja durante o después de la reproducción, pero los de las hembras fueron mayores luego del período reproductivo. Poco después de que los polluelos emplumaron, los adultos abandonaron el Great Basin principalmente hacia sitios costeros o estuarinos de la Bahía de San Francisco. Una vez que las aves llegaron a la costa, se movieron poco entre sitios, y los individuos parecieron ser fieles a sus sitios en inviernos subsiguientes. Los sitios de invierno de C. s. inornatus en el Great Basin occidental difirieron de aquellos usados por aves de otras áreas del rango de esta subespecie, sugiriendo que otra subespecie o una sección poblacional distinta podría existir. Este estudio ilustra la importancia de entende

Susan M. Haig, Lewis W. Oring, Peter M. Sanzenbacher, and Oriane W. Taft "SPACE USE, MIGRATORY CONNECTIVITY, AND POPULATION SEGREGATION AMONG WILLETS BREEDING IN THEWESTERN GREAT BASIN," The Condor 104(3), 620-630, (1 August 2002). https://doi.org/10.1650/0010-5422(2002)104[0620:SUMCAP]2.0.CO;2
Received: 19 November 2001; Accepted: 1 March 2002; Published: 1 August 2002
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