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Seasonal Distribution of Birds at a Cloud-Forest Locality, the Anchicayá Valley, in Western Colombia3

Steven L. Hilty
Ornithological Monographs
No. 48, Studies in Neotropical Ornithology Honoring Ted Parker (1997), pp. 321-343
DOI: 10.2307/40157541
Stable URL: http://www.jstor.org/stable/40157541
Page Count: 23
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Abstract

This study presents information on the seasonal status of a cloud-forest avifauna on Colombia's Pacific Andean slope at 950-1050 m elevation. Two hundred seventy-one species were recorded at the 70-80 ha site. About 64% of these were year-round residents. The remainder (36%) were vagrants and species showing varying degrees of seasonal movements; 22% were short-distance (elevational or local) migrants, 8% were long-distance migrants from North America. Short-distance migrants were predominantly frugivores and nectarivores; over half (58%) of all nectarivores were elevational migrants. Seasonal movements were recorded in all months, but short-distance migrants were most numerous March-June and November-January, periods when migrants from both the highlands and lowlands were present. The abundance of flowers and fruits also showed two small peaks. About twice as many short-distance migrant nectarivores came from high elevations as low elevations. A majority of short-distance migrant frugivores also were from the highlands. Eight Tangara tanagers, although resident, showed significant expansions and contractions of foraging range, diversity of fruit eaten, and amount of fruit included in their diet, an indication that these birds track resource levels, and that variation in fruit abundance affects the dynamics of frugivore populations. /// Este estudio muestra una información preliminar de cambios estacionales de la avifauna de un bosque nublado en la vertiente pacifica de los Andes colombianos. Se registró un total de 271 especies en un área entre 70-80 ha. Alrededor de un 36% de las especies mostraron evidencias de movimientos estacionales; 22% presentaban movimientos altitudinales o locales y 8% eran aves migratorias de larga distancia que se reproducen en Norte América. Las aves migratorias de corta distancia eran principalmente nectivoros y frugiforos; 58% de los nectivoros eran aves migratorios que se presentaban movimientos altitudinales o locales. Los movimientos estacionales fueron complejas y distribuidos a lo largo del año, pero más aves migratorias de corta distancia estuvieron presente durante los períodos de marzo a junio y de noviembre a enero, epocas cuando provenía especias de elevaciónes mayores y menores. La abundancia de flores y fruitas tambien mostraron evidencias de cambios estacionales. Los nectivoros migratorios provenía predominantemente de elevaciónes mayores; tambien la majoría de frugíforos estacionales provenía de regiones altas. Ocho especies de Tangara no mostran evidencias de movimientos altitudinales pero mostraron aumentos y reducciónes de sus rangos de alimentaciones, equalmente en la diversidad y cantidad de frutas consumidos.

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