Rodent occupancy in grassland paddocks subjected to different grazing intensities in South Brazil

Abstract

Livestock is promoting the global collapse of mammal populations. The discovery of the best management practices that reconcile conservation with production is urgently needed. We evaluated the effect of cattle grazing on the occupation of three rodent species (Akodon azarae, Oligoryzomys flavescens and Oxymycterus nasutus). We collected habitat covariates and sampled rodents, using live traps and tracking tunnels, in 20 paddocks subjected to different grazing pressures, from two research stations, across four seasons. We applied single-season occupancy modeling to determine whether rodent detection and occupation varied as a function of the covariates describing sampling occasions and grazing intensity. We ran sensitivity analyses to evaluate the effect of the differential sampling effort we applied across research stations. All species had higher detection probabilities during the winter. O. nasutus showed a higher detection probability under tall vegetation. A. azarae reached a higher occupation probability in ungrazed areas, although it also had a low probability of occupation in highly grazed paddocks. O. flavescens occupation seemed constant across the grazing gradient. O. nasutus reached a higher occupation probability in ungrazed areas. Decreasing stocking rates and maintaining ungrazed areas might compose the best management practices for small mammal conservation in the grasslands of Southern Brazil.

Keywords

• Beef production
• Cattle raising
• Detectability
• Land sparing
• Non-volant small mammals
• Pampa biome