Determining the factors that influence the occurrence of Bare-faced Curassows (Crax fasciolata) in Humid Chaco, northern Argentina

摘要

Identifying factors that determine the spatial distribution of threatened species is key to ensuring their conservation. The Bare-faced Curassow (Crax fasciolata) is a globally threatened bird that is categorized as Vulnerable, and its populations are declining in the gallery forests of the Humid Chaco. To evaluate the effect of human activities and environmental characteristics on the occupancy of Bare-faced Curassows, we sampled 48 sites along two rivers in northern Argentina. Bare-faced Curassows were recorded in 46% of the sites visited. The anthropic activities were identified as hunting pressure, selective logging of timber, and livestock production. Hunting and logging were positively associated with each other, and in turn, negatively related to village distance. We evaluated 17 occupancy models using six predictive variables. Occupancy by the Bare-faced Curassow was positively influenced by the distance to the nearest village and by forest cover. To a lesser extent, occupancy was also positively associated with an increase in availability of trees with fleshy fruits and with river course length. Our results indicate that hunting pressure and selective logging are limited by the cost of access from populated areas. Thus, distance to the villages was a good indicator of these human activities along the gallery forests and could be used to determine the spatial distribution of the Bare-faced Curassow in its southern range. Our study highlights the value of using presence/absence surveys and occupancy models for assessing threats of threatened and elusive species such as cracids.