Environmental factors influencing the geographical distribution of the lesser rhea in southern argentine Patagonia.

PEDRANA, J.; BUSTAMANTE, J. ; TRAVAINI, A.; RODRIGUÉZ, A.; ZAPATA, S.; ZANÓN MARTÍNEZ, J.I.; PROCOPIO, D.

EMU

CSIRO PUBLISHING

Año: 2011

0158-4197

The Lesser Rhea (Rhea pennata pennata) is an endemic bird of the Patagonian steppes which has suffered a marked and progressive decline in numbers over the last decades. We hypothesized that this decline is due to the management of livestock production and unregulated hunting. Our aim was to investigate the factors that determine Lesser Rhea distribution in southern Patagonia and to generate a predictive cartography at the regional scale. We surveyed 8000 km of roads in Santa Cruz, Argentina and recorded 795 Lesser Rhea sightings. We estimated environmental predictors from remotely sensed data and analysed Lesser Rhea occurrence in relation to these predictors. Predictors used were associated with four hypotheses of Lesser Rhea regional distribution, namely rancher control, productivity, topography, and anthropogenic disturbance. We built models for each hypothesis, evaluated and compared their predictive power by cross-validation. Our results suggest that Lesser Rhea distribution is not negatively affected by rancher control, as the species is more abundant in areas with high sheep stocking levels, but it is positively influenced by primary productivity and negatively by the proximity of urban areas and oil camps. Our results provide a distribution map that can be used as a management tool for government agencies and highlights the conservation priorities for managing this declining and emblematic species.