Seasonal Variation in the Diet Composition and Dietary Overlap in Five Trachylepis Skink Species in Arid South-Western Africa

Diet of five Trachylepis skink (T.spilogaster, T.acutilabris, T.sulcata, T.hoeschi, T.occidentalis) was studied through stomach content analysis. Skinks were collected in arid habitats in western Namibia. In all these species, active predatory strategy predominates. All skink species preyed almost exclusively on insects. Among insects four taxa comprised the bulk of diet in all five species investigated: beetles (Coleoptera), grasshoppers (Orthoptera), termites (Isoptera), ants (Hymenoptera: Formicidae) and larvae. Their overall contribution changed from 92.2% to 97.7% of all prey items in the diet of particular skink species. These insects are among the most common invertebrate groups in arid regions of southern Africa. Most prey items (ants, termites, spiders, most beetles, flies) were below 10 mm long. All main prey groups were recorded in dry and wet season in all five skink species. Both males and females fed on the same prey groups, but there were marked differences in the proportions of these groups in particular skink species. In general males preyed more on beetles, while females – more on ants. Niche breadth ranged from 0.25 in T. occidentalis to 0.47 in T.hoeschi. The highest overlap of feeding niches was recorded between T. spilogaster and T. sulcata, and between T.spilogaster and T.acutilabris; while the lowest overlap was recorded between T.acutilabris and T.sulcata, and between T.sulcata and T. hoeschi.