Space use and home range size of the freshwater turtle Hydromedusa maximiliani (Testudines: Chelidae) in Southeastern Brazil

Identifying the habitat area used by animals is vital for understanding species-level life-history traits and ecological requirements. The Maximilian’s Snake-necked Turtle (Hydromedusa maximiliani) is an endemic and endangered freshwater turtle from the Atlantic Rainforest in Brazil. We tracked 14 adult Hydromedusa maximiliani (seven males and seven females) with radio-transmitters at the Parque Estadual Carlos Botelho, southeastern Brazil. We also monitored 22 turtles (11 males and 11 females) with thread-bobbins to evaluate habitat use and selection. We calculated movement distances with linear measurements and estimated home ranges sizes using five home range estimators: (1) Brownian Bridge Movement Models (BBMM), (2) dynamic Brownian Bridge Movement Models (dBBMM), (3) Autocorrelated Kernel Density Estimator (AKDE), (4) Minimum Convex Polygons (MCP), and (5) Kernel Density Estimators (KDE). Home range sizes varied between 0.4 and 137.4 ha throughout a year of monitoring. These estimates differed depending on the estimator method applied, with BBMMs showing larger areas overall. Home range sizes did not differ between sexes; however, males were more likely to overlap either with females or other males. Hydromedusa maximiliani used stream-bank burrows as refuge, showing the importance of shelter for this turtle species. We observed small individuals occupying shallow pool habitats more often than adults. Our estimates of home range size are the first reported for this species.