Seed consumption and dispersal by the spur-thighed tortoise Testudo graeca

Seeds belonging to 34 species, mainly Poaceae, Asteraceae and Juncaceae, were identified in a sample of 170 faecal pellets of Testudo graeca L. from Dofiana Biological Reserve, Huelva province, Spain. The effect of the digestion of these chelonians on the seeds of Spergula arvensis, Hypochaeris glabra, Rumex bucephalophorus, Ornithopus sativus, Briza maxima and Lavandula stoechas was studied. The average period of retention in the digestive tract was found to be 5.3 d and the percentage of recovered seeds in the faeces was 19.3 (6.5-34.2). All seeds germinated, except in H. glabra and L. stoechas, suggesting that T. graeca is a disperser for these species. Seeds of S. arvensis that pass through the digestive tract of the tortoise show increased germination compared with controls.