From 1998 to 2000 we used radio telemetry to study habitat use by greater rheas Rhea americana in rural areas. Captive-born greater rheas preferred pastures to grasslands and did not use crops. No differences in habitat use were found between wild and captive-born greater rheas. Wild individuals preferred pastures, showed less preference for grasslands, and did not use crops. Rheas used pastures and grasslands for nesting but they did not use crops. No differences in nesting success was detected between these habitats. Our results show that agroecosystems that include grasslands and pasture production would strongly contribute to the conservation of this species. However, poaching must be controlled to ensure long-term persistence of wild populations of greater rheas.