Invertebrate prey and predatory behaviour of the omnivorous African tortoise<i>Kinixys spekii</i>

Abstract

Abstract Invertebrates form an important part of the diet in the omnivorous African tortoises of the genus Kinixys . Millipede prey of Kinixys spekii in Zimbabwe had a mean volume of 0.9 ml, and made up 64.7% of invertebrate food by volume; beetles made up most of the remainder and had a mean volume of 1.4 ml. The mean mass of invertebrate prey was 0.19% of tortoise mass, a similar value of relative prey mass to many insectivorous lizards. Tortoises preferentially attacked moving millipedes at or just behind the head, but predatory behaviour was otherwise unspecialized, with tortoises killing millipedes by ingesting them in pieces. Handling times of millipede prey varied significantly with relative prey mass, defensive behaviour, and direction of ingestion. The profitability (mass intake/handling time) of millipedes was maximal at a relative prey mass of 0.2%; the basis on which prey are selected is discussed.