grassland Argentina 56 Aves 24 South America 24 Pampas 22 bird 20 Poaceae 14 Grassland 12 agricultural ecosystem 12 phylogeny 12 rodent 12 species diversity 12 Animals 10 Phylogeny 10 Rodentia 10 abundance 10 controlled study 10 endangered species 10 land use 10 nonhuman 10 Buenos Aires [Argentina] 9 article 8 biodiversity 8 biome 8 conservation status 8 grazing 8 human activity 8 land use change 8 passerine 8 species richness 8