High dependence on protected areas by the endangered giant armadillo in Argentina

A combination of technics was used to assess landscape variables associated with the presence of the globally vulnerable giant armadillo (Priodontes maximus) in its southernmost distribution in the Chaco region of Argentina. Between 2017 and 2019, 369 km of foot and vehicle transects were run to search and record indirect evidence of the species (burrows and feeding excavations) in areas with different level of protection, including two national parks, three provincial parks, and non-protected areas. Distance sampling was used to estimate density of excavations and effective strip width sampled to estimate the surveyed area. Resource selection functions (RSFs) were used to assess the variables associated to its presence by comparing locations of excavations with available habitat within surveyed areas. In these RSF models covariates that may affect habitat use and survival of giant armadillos were included: three categorical ones: soil type, vegetation cover (forests vs. grasslands), protection level (national park, provincial park, non-protected), and five continuous variables: distance to nearest river, distance to nearest national park, distance to closest protected area, distance to nearest transformed area, and distance to natural grasslands. Habitat use was modelled pooling together burrows and feeding excavations, and models were validated with a pool of records previously excluded from the analysis. A total of 104 records of burrows and 344 of feeding excavations were recorded. The probability of occurrence of giant armadillo excavations was much higher within forests, within or near protected areas, and increased with the distance to rivers, to transformed areas, and to grasslands. In the study area, only 10% of the landscape surveyed has good- to high-probability of occurrence of giant armadillos. The maintenance of large surfaces of native forests and the consolidation, improvement, and connectivity among protected areas seem to be essential for the long-term survival of the endangered giant armadillo in Argentina.