Occurrence and ecological aspects of the two-fingered skink Chalcides mauritanicus in the Chafarinas Islands in North Africa

Abstract

The two-fingered skink, Chalcides mauritanicus, is a fossorial species from North Africa, where it has only been found at a few localities on sandy sea shores. Virtually nothing is known about its ecology. For the first time, we report the occurrence of an apparently large and well-preserved population of C. mauritanicus on the Chafarinas Islands (NW Africa). In addition, we study some aspects of the morphology and ecology (microhabitat, soil and diet selection) of this skink. Adult females were larger than males but had heads of similar size. In this population, we found an equilibrated sex ratio. Adults showed a very high frequency of regenerated tails, suggesting a high predation pressure. Skinks were restricted to a small area of Congreso Island where, far from the sea shore, they selected sandy microhabitats. These microhabitats were characterised by higher cover at the substrate level of bare soil and medium rocks, lower cover of leaf litter and grass, and more sparse subarboreal vegetation than available microhabitats. Soils occupied by skinks had a higher proportion of sand, and a lower proportion of gravel, silt and clay, resulting in a much lower soil compaction than most soils of the island. The bulk of the diet of C. mauritanicus consisted of small beetle larvae, which were consumed in higher proportions than expected by their availability.

Key words:

• Skinks
• Chalcides
• morphology
• diet
• habitat selection
• North Africa

Acknowledgements

We thank three anonymous reviewers for helpful comments, the personnel and facilities of the field station of the “Refugio Nacional de Caza de las Islas Chafarinas” for providing logistical support. We thank Ángel Sanz, Francisco López, Alfredo Ruiz and Javier Zapata for friendship and help in the Islands. R. García-Roa benefited from a FPI grant, J. Ortega from a CSIC JAE-pre grant, A. Pérez-Cembranos from a FPU grant of the Spanish Ministry of Science and Education and A. León from a predoctoral grant from the University of Salamanca. Legal authorisation and support for the study was provided by the Organismo Autónomo de Parques Nacionales (Spain), with additional financial support from the Ministerio de Ciencia e Innovación research projects CGL2009-12926-C02-02, CGL2011-24150/BOS and CGL2012-39850-CO2-02, from the Regional Government of Andalusia project BIOGEOBIRD (P09-RNM-4987) and from FEDER funds.