Local extinctions and changes in species richness of grassland birds in relation to changes in agricultural land-use in the Pampas region of Argentina.

RABUFFETTI, FABIÁN; DI GIACOMO, ADRIÁN S.; REBOREDA, JUAN C.

Brasilia, Brasil

Congreso; XIX Annual Meeting of the Society for Conservation Biology; 2005

Society for Conservation Biology

One of the main causes of decline and extinction in birds is habitat loss and fragmentation. We analyzed patterns of local extinction of grassland birds associated with intensification of agriculture during the last 100 years in the Pampas region of Argentina. We focused our analysis in 111 species that depend partially or totally on grasslands. We analyzed: 1) the proportion of species that have been extirpated locally since 1900 in four districts that experienced different degrees of agricultural intensification (proportion of its area converted to croplands), and 2) present richness of grassland birds in 15 districts with different degrees of agricultural intensification. The proportion of grassland birds locally extirpated during the last 100 years varied between 15 and 45%. Local extinctions were more severe in districts with greater conversion of grasslands to croplands. The temporal pattern of extiction progressed from local to regional. The present richness of grassla nd birds (range 44-77 species per district) was negatively associated with the proportion of the district area converted to croplands (range 1-70%). Our results show that changes in agricultural land use during the last 100 years within the Pampas grasslands are associated to local extinction of grassland birds.