Abundance and habitat distribution of raptors in the sierra de San Javier biological park, northwestern Argentina

Abstract

Abundancia y distribución de aves rapaces en el Parque Biológico Sierra de San Javier, noroeste de Argentina. – Presentamos los patrones de utilización de hábitat para 27 especies de aves rapaces del Parque Biológico Sierra de San Javier. Registramos en total 20 especies diurnas y 7 de hábitos nocturnos; 70% de ellas habitan con regularidad el área relevada. En los hábitat principales, realizamos un análisis cualitativo de la abundancia y de la distribución temporal estacional de las especies. Las especies más abundantes son residentes permanentes, ampliamente distribuidos en Sudamérica. La riqueza de especies fue mayor para los carnívoros y menor para los insectívoros en los tres hábitat principales del parque, mientras que los carroñeros fueron el grupo funcional más abundante en los tres casos. Discutimos la contribución del parque para la conservación de especies de aves rapaces susceptibles de extinguirse a escala local. El Milano pico garfio (Chondrohierax uncinatus) y el Taguató negro (Buteo leucorrhousi) poseen alto riesgo de extinción local, debido a su disminución numérica, susceptibilidad a la alteración del hábitat y alprogresivo aislamiento del parque. Ocho especies utilizan con regularidad el tipo de hábitat donde su abundancia es mayor [Jote real (Sarcoramphus papa), Aguilucho cola corta (Buteo brachyurus), Halcón montéschico (Micrastur ruficollis) y Lechucita canela (Aegolius harrisii) en el bosque montano subtropical; Milano blanco (Elanus leucurus), Chimango (Milvago chimango), Halconcito colorado (Falco sparverius) y Lechucita vizcachera (Speotyto cunicularia) en los bosques alterados]. Estas especies son potencialmente útiles como indicadoras de la calidad del hábitat y para evaluar el impacto de la modificación y fragmentación de los hábitat naturales sobre la vida silvestre del parque. Aceptado el 10 de Mayo de 2004.Abstract. – We describe patterns of habitat use for 27 species of raptors in the Sierra de San Javier Biological Park in northwest Argentina. Twenty diurnal and seven nocturnal species were recorded; 70% of them regularly inhabit the area. For the main habitats, we present a qualitative analysis of species seasonal distribution and abundance during the dry and wet seasons. The most abundant species were permanent residents that are widely distributed in South America. Species richness was highest among carnivores and lowest among insectivores in the three main habitats of the park, while scavengers were the most abundant functional group in all habitats. We discuss the importance of the park for the conservation of species susceptibleto local extinction. The White-rumped Hawk (Buteo leucorrhous) and the Hook-billed Kite (Chondrohieraxuncinatus) seem to be at high risk of local extinction because of their decrease in number,susceptibility to forest degradation, and the progressive isolation of the park. Eight species regularly used the habitat where their abundance was highest [King Vulture (Sarcoramphus papa), Short-tailed Hawk (Buteo brachyurus), Barred Forest-Falcon (Micrastur ruficollis), and Buff-fronted Owl (Aegolius harrisii) in the mature subtropical montane forest; and White-tailed Kite (Elanus leucurus), Chimango Caracara (Milvago chimango), American Kestrel (Falco sparverius), and Burrowing Owl (Speotyto cunicularia) in disturbed forests]. These species are potentially useful as indicators of habitat quality and in assessing the impact of habitat fragmentation and modification on the park’s wildlife.Key words: Argentina, conservation, ecological indicator, raptor, subtropical montane forest, Tucumán.

We describe patterns of habitat use for 27 species of raptors in the Sierra de San Javier Biological Park in northwest Argentina. Twenty diurnal and seven nocturnal species were recorded; 70% of them regularly inhabit the area. For the main habitats, we present a qualitative analysis of species seasonal distribution and abundance during the dry and wet seasons. The most abundant species were permanent resi- dents that are widely distributed in South America. Species richness was highest among carnivores and lowest among insectivores in the three main habitats of the park, while scavengers were the most abundant functional group in all habitats. We discuss the importance of the park for the conservation of species susceptible to local extinction. The White-rumped Hawk (Buteo leucorrhous) and the Hook-billed Kite (Chon- drohierax uncinatus) seem to be at high risk of local extinction because of their decrease in number, susceptibility to forest degradation, and the progressive isolation of the park. Eight species regularly used the habitat where their abundance was highest [King Vulture (Sarcoramphus papa), Short-tailed Hawk (Buteo brachyurus), Barred Forest-Falcon (Micrastur ruficollis), and Buff-fronted Owl (Aegolius harrisii) in the mature subtropical montane forest; and White-tailed Kite (Elanus leucurus), Chimango Caracara (Milvago chimango), American Kestrel (Falco sparverius), and Burrowing Owl (Speotyto cunicularia) in disturbed forests]. These species are potentially useful as indicators of habitat quality and in assessing the impact of habitat fragmentation and modification on the park’s wildlife.