The return of the giant otter (Pteronura brasiliensis) to Tauramena (Casanare, Colombia): relative abundance, distribution, and conservation considerations

Abstract

The giant otter (Pteronura brasiliensis) is endemic to South America, and in Colombia it is distributed in the Amazon and Orinoquia regions. It inhabits rivers, streams, and lagoons, but prefers the latter two in response to resource availability depending on the season. Giant otters are endangered in Colombia, and aspects of their natural history are still unknown in much of their geographic range. Our research aim is to generate information focused on relative abundance, habitat use, and distribution of the giant otter in an area of Colombia where it was thought to be extirpated. The distribution was evaluated with spatial distribution modeling (SDM) and habitat use using the Wallace 2.0.4 package for the department of Casanare in northeastern Colombia. To assess the population status and abundance in the municipality of Tauramena, 30 transects were surveyed in the Tua River and the Piñalito and El Huesero streams in 2021 and 2022. In general, the distribution models highlighted the importance of precipitation, temperature, and forests for the occurrence of this species. In Tauramena, five family groups were detected, which were composed of an average of 4.83 ± SD 3.16 individuals per group and a relative abundance of 1.03 ind./km. These are positive results for giant otters, as they indicate signs of population recovery of a species previously thought to have been extirpated from this region because of hunting and illegal pelt trade. Even though Tauramena is an area with high levels of anthropic disturbances, giant otters are showing signs of adaptability and plasticity, which provide important conservation opportunities. It is expected that this work will become the first step for the generation of additional information on diet, behavior, and population structure that can inform management plans for the giant otter in Colombia.