Soil characteristics determine microhabitat selection of the fossorial amphisbaenian Trogonophis wiegmanni

Correspondence José Martín, Departamento ae Ecología Evolutiva, Museo Nacional de Ciencías Naturales, eSle, José Gutiérrez Abaseal 2, 28006 Madrid, Spaín, Tel. +34914111328; Fax: +34 915645078 Email: [email protected] Amphisbaenians are reptiles specialized for a fossoríal lifestyle, which may limit their opportunities for microhabitat selection in comparison with epigeal reptiles, \Ve hypothesized that. given the fossorÍal ha bits of amphisbaenians. a detailcd analysis of the physical and chemical properties of the soil may reveal their patterns of habitat use, \Ve investigated microhabitat and soil use by a population of the amphisbaenian Trogonophis H,iegmWJI1i from the Chafarinas Islands (North\Vest Africa) and compared them with those available in the habitat. Results showed that sorne soil physical and ehemical characteristics determined microhabitat use by T. wiegmanni. Amphisbaenians selected soils that were relatively sandy. basic. carbonated and shallow, having a high cover of medium-sized rocks, whereas they avoided marine salinized, more acid and deeper heavytextured soíls (í.e. with percentages 01' silt eomparatively high), and those covered mainly by small rocks. No differences were found betwecn soíls with and without influence of seabírd colonies, although this was the main driver of soil ehemicaJ variations in these Islands. Vegetation cover per se did not seem to havc a direct influence on microhabitat use, \Ve discuss how energetic costs of burrowing anu the direct and indirect influences of s011 chemical propertíes could explain these patterns of habitat use.