Testudo graeca graeca feeding ecology in an arid and overgrazed zone in Morocco

Terrestrial chelonians of arid regions are frequently faced with highly variable food quality and/or quantity and these problems could be aggravated in overgrazing areas. Then, it is crucial for species conservation to possess precise data on feeding ecology. In this paper, we provide the first quantitative data on Testudo graeca graeca feeding ecology, in the central Jbilets (Morocco). Diet composition was obtained by faecal analysis and compared to plant assemblages in the field. Interestingly, T. g. graeca seems rather a specialist herbivorous tortoise. The five main plant species found in faecal samples (Leontodon saxatilis (Asteraceae); Malva parviflora (Malvaceae); Astragalus cruciatus, Medicago hispida and Lotus arenarius (Fabaceae)) represent 70% of the identified material and are highly preferred whereas several other plant species, common in the field (e.g. Eryngium ilicifolium (Ombellifereae); Emex spinosus (Polygonaceae); Spergula flaccida Caryophyllaceae)) are actively avoided. Fabaceae made up 27% of the diet and may be important forbs in the diet of terrestrial tortoise owing to their high nutritional value. The diet composition of T. g. graeca suggests that diet overlap may occur between domestic ungulates and tortoises in overgrazed landscape and could generate a competition context. However, T. g. graeca seems to focus its foraging effort under the spiny shrubs where the impact of overgrazing is strongly attenuated.