Density, population structure and activity pattern of Hydromedusa tectifera (Testudines-Chelidae) in a mountain stream of Córdoba province, Argentina

Abstract

The Snake-necked Turtle (Hydromedusa tectifera) is mainly distributed in the northeastern provinces of Argentina; however, some isolated populations occur in central Córdoba. This is the first report on some ecological aspects of one of these populations. Population density and annual activity pattern were characterized at Toro Muerto Stream in the Sierras region of the Córdoba province, central Argentina. Turtles were hand-captured and sex and carapace length were determined for each individual. Mark-recapture data were used to estimate population density, variation in monthly capture rates, and sex ratios throughout the sampling months. A total of 96 turtles were captured and density was estimated at 218 individuals ha-1. Individuals were captured all year round, but showed activity peaks in spring and summer. This seasonal pattern has also been observed in other freshwater turtles. During the mating season a higher number of males were captured, which suggested a seasonal difference in activity patterns between sexes. © 2008 Koninklijke Brill NV, Leiden.