Title
Habitat modeling of Dahl’s toad-headed turtle (Mesoclemmys dahli) in Colombia
Author(s)
Forero-Medina, German; Cárdenas-Arévalo, Gladys; Castaño-Mora Olga
Published
2012
Publisher
Herpetological Conservation and Biology
Abstract
Dahl’s Toad-headed Turtle (Mesoclemmys dahli) is an endemic and threatened species from Northern Colombia. It was originally described by Zangerl and Medem (1958) but information on its distribution, natural history, and ecology has been limited. Recent research and conservation efforts have contributed to the identification of new populations and a broader understanding of its natural history. There is, however, no quantitative assessment of the species’ potential distribution in Colombia, or studies of the factors that make certain areas suitable for the species. This type of information is important for developing and continuing species-specific conservation strategies. We modeled the habitat distribution of M. dahli at three spatial scales. We first modeled the species geographic distribution at an ecoregional scale in Colombia using presence-only data (known localities) and a maximum entropy (Maxent) model. Second, we evaluated the factors that differentiate the first order streams where the species occurs vs. those where it is absent at the locality of Chimichagua, Cesar (9°17.717'N, 73°47.741'W), during the dry season (December to March).
Finally, we evaluated the habitat variables associated with the presence of turtles at trap sites within the streams in Chimichagua. Our model predicts the presence of this species in seven departments in Northern Colombia, occupying an area of about 32,700 km2. This estimate of the range represents a potential range extension of approximately 9,000 km2 compared to the previously known distribution. The model, however, does not inform us about habitat quality or abundance of the species throughout this range. The tropical dry forest ecosystem, which was the most important variable explaining the species range, has been heavily transformed by human activities and is remarkable for its low level of formal protection. In Chimichagua, the species was associated with first order streams (1–10 m width), with slow flowing (< 0.22 m/sg) and dark water (< 32 cm clarity). In this same locality, within the streams where it occurs, the species was associated with portions of the stream that had considerable (> 82%) canopy cover and pools deeper than 78cm. This highlights the importance of the riparian vegetation for the species.
Keywords
classification trees; Colombia; distribution; geographic range; habitat; Maxent model, Mesoclemmys dahli
Access Full Text
Back
DMX1370200000