INCITAP   20787
INSTITUTO DE CIENCIAS DE LA TIERRA Y AMBIENTALES DE LA PAMPA
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Winners and losers among open-habitat raptors due to agricultural intensification of Argentine Pampas
Autor/es:
SEOANE, J.; SARASOLA, J.H.
Reunión:
Conferencia; I Worldwide Raptor Conference; 2013
Resumen:
The Argentine pampas biome is one of the largest in southern South America and has a great relevance both as breeding areas for some specialized raptors and as wintering areas for Neotropical migratory birds of prey. It is suspected that ample land use changes occurred in Argentine pampas during the last decade (due to conversion of former ranches to industrialized agricultural fields, mainly for soybean implantation) may have led to a decrease of species linked to cattle rearing practices and an increment of more tolerant species. In this study, we compare two extensive surveys done in 2002-3 and 2012-13 with the aim of assess changes in (1) relative abundance and (2) species-habitat relationships in the raptors assemblage during the last decade. Sixty seven 30x30 km squares were surveyed for raptors, each by 7 car transects and 8 observation points. Land-use and habitat descriptive variables were estimated at the observation points and changes in coverage for this land-use and habitat types were used as predictors of changes in raptor abundance during the same period. A total of 8032 and 6722 raptors were recorded during surveys conducted in 2002 and 2012, respectively. Ten out of 17 raptors species recorded decreased in number, some noticeably (50% reduction), while six increased in number (particularly the Falco species) and one (Geranoaetus melanoleucus) appeared in 2012 and was not registered in 2002 surveys. Major changes in land use type during this period were due to reduction in coverage of woodlands and lagoons, this last ones probably associated to severe drought conditions in 2011-2012, and increase in the area devoted to crops and urban development. The squares with major changes in land-use and habitat compositions showed the greatest changes in raptor assemblage composition. Our results confirm the vulnerability and susceptibility of birds of prey to the ongoing landscapes changes in Argentine pampas.