Seasonal activity patterns and diet divergence of three sympatric Afrotropical tortoise species (genus Kinixys)

Abstract

Three species of hinge-back tortoises (Kinixys belliana nogueyi, Kinixys erosa, Kinixys homeana) are found in simpatry in the rainforests of the Niger Delta, southern Nigeria (west Africa). The seasonal activity patterns and food habits of these tortoises are studied in the present paper. K. erosa and K. homeana have similar activity patterns, with peaks occurring during the wet season. Kinixys belliana was found only during the wet months. There was no evidence of any specific effect of humidity of the air on their activity intensity, and it seems likely that, more than absolute values of air humidity, the crucial factor to force tortoises into high activity is the sudden change between dry days and very wet days at the onset of the rainy season (end of March-early April). K. homeana was significantly more active in the early phase of the wet season. Common items, which were consumed by all three predator species, were: plant matters, fruits and berries, fungi, Oligochaeta, and Gastropoda Pulmonata, whereas Araneidae were also consumed by all species, but much more rarely. Common prey items, which were consumed by K. homeana and not by K. erosa were: Coleoptera larvae, Dermaptera, and termites. K. homeana appeared more generalist than K. erosa, and the respective diets diverged considerably both in dry and in wet seasons. On the other hand, the diets of K. erosa and K. belliana were more similar (at least in wet season).