Abundance and activity of Chelonoidis chilensis (Gray, 1870) in the Chaco-Monte ecotone of central Argentina region

Abstract

Turtles represent one of the most threatened groups of vertebrates. Habitat loss by expansion of the agricultural frontier, exploitation and unregulated trade are the primary causes for sharp declines in many turtle species. Chelonoidis chilensis is a widespread turtle having the broadest distribution in South American continent, it has recently been reclassified from threatened to vulnerable. Considering this, it is necessary to search for non-invasive study methods that allow us to safely assess its ecological traits and monitor its populations. The objective of this work was to evaluate abundance and activity patterns of C. chilensis, using conventional and non-invasive methodologies in different years and vegetation types in Sierra de las Quijadas National Park. Conventional methodology consisted in sampling a study area through 5m width visual detection transects, placed one adjacent to another, involving a total of 168 transects (216 has). This sampling was repeated twice, with a one-year interval. Non-invasive novelty methodology consisted of using ten camera traps that were installed for two years. Turtle frequency in different vegetation types, activity patterns according to temperature and sex ratio were determined. The abundance of C. chilensis registered was 0.027 (in 2016) and 0.036 turtles/ha (in 2017). Temporal activity, observed through camera-traps, was detected between 25 to 40 °C and from 8 am to 8 pm. The results allow us to conclude that the abundance in the park is lower than what has been reported by several authors in other Chaco regions. In this sense, further studies should be made on this ecotonal region to assure the protection of this vulnerable species. This study is the first to report abundancy and activity patterns of C. chilensis in the ecotonal region with the novelty of using a non-invasive method for monitoring the species.