Seasonal variation in stomach contents and diet composition in the large girdled lizard, Cordylus giganteus (Reptilia : Cordylidae) in the Highveld grasslands of the northeastern Free State, South Africa

Cordylus giganteus is endemic to the Highveld grasslands of South Africa. O wing to limited distribution and extensive habitat destruction, it may be r egarded as an endangered species. C. giganteus individuals fed during eight months of the year. The mass of food in the stomachs and remains in the hi nd guts indicated that a high degree of foraging success occurred during th e warm spring and summer months in association with seasonal variation in r esource abundance. Analysis of the contents of 480 stomachs revealed that t he diet of C. giganteus in the study area consisted almost exclusively of a rthropods, with six of the major taxa (Coleoptera, Diplopoda, Hemiptera, Hy menoptera, Orthoptera and Lepidoptera) accounting for 80 % of the total num ber and 90 % of the gravimetric contribution of ingested food by the differ ent age and sex groups. Coleoptera dominated as prey category throughout th e seasons. The consistency of the main food categories in spring, summer an d autumn suggest that prey selection took place, and that C. giganteus is o pportunistic only in the sense of taking other prey taxa when they are pres ent in greater abundance. All the major prey types in the diet showed negat ive relationships between relative abundance and selectivity, indicating th at C. giganteus preferred a prey type more when it was relatively less abun dant in the environment. Measurement of dietary overlap for prey taxa indic ated a high degree of dietary similarity for all age and sex classes.