What do myrmecophagous geckos eat when ants are not available?: comparative diets of three Socotran species

Abstract

The diet of three populations of semaphore geckos (Pristurus) from Socotra archipelago is analysed based on 82 faecal pellets. Pristurus samhaensis from the small islands of Samha (n = 18) and Darsa (n = 24) and P. sokotranus from the main island of Socotra (n = 40) were compared. Like other Pristurus species, P. samhaensis on Samha and P. sokotranus on Socotra were highly myrmecophagous (76.7% and 38.6% ants, respectively). However, ants were absent from the diet of P. samhaensis on Darsa. In contrast to the rich native ant fauna of the other islands, only one ant species was reported for Darsa, Pheidole teneriffana, likely a recently introduced species. Pristurus samhaensis seems to have overcome this scarcity in ant prey by consuming substitute prey, namely Coleoptera and Heteroptera, which are secondary for the other two populations studied. The two P. samhaensis populations inhabiting the small islands displayed less diverse diets compared to that of P. sokotranus from the main island where vegetation structure was more complex. Prey items of P. samhaensis from Darsa were also smaller than those of P. sokotranus from Socotra, those of P. samhaensis from Samha being intermediate. It remains unclear how ancient these differences are, but they are probably too recent to have promoted special morphological and ecological adaptations in these geckos.

African Zoology 45(1): 115–120 (April 2010)