Anteaters on the edge: giant and lesser anteaters (Myrmecophaga tridactyla and Tamandua tetradactyla) at their geographic distributional limits in Paraguay

Abstract

ABSTRACT Species tend to be less abundant at the limits of their geographic distribution. Giant and lesser anteaters have their southernmost limits in Argentina and Paraguay, where scarce information exists regarding their ecology and conservation. We present a study carried out in the Paraguay River floodplain, in an area dedicated to cattle rearing using native grasses in a subtropical flooded savanna associated with naturally occurring forest islets, wetlands and palm groves. Using camera-traps within three different forest types, we estimated parameters related to habitat preference, social behavior and activity patterns of both species. Results show that capture success was greater in the Floodable sub-humid forest islets (FSF), compared to other types of forests: Riparian forests associated with wetlands (W-RF) and Mesoxerophytic semi-deciduous forests dominated by Schinopsis balansae (MXF). Most detections corresponded to solitary anteaters, although mother-young pairs were occasionally observed during summer. Both species showed a nocturnal and crepuscular activity pattern with a peak of records around midnight. Myrmecophaga tridactyla was detected between 11°C and 26°C, while Tamandua tetradactyla occurred between 15°C and 23°C. Future research that incorporates systematically taken data in other different habitats, including grasslands and shrublands, during all seasons of the year is recommended.