The Herpetological Journal

pp.105-114

Authors: Ronald E. Willemsen And Adrian Hailey

Abstract: Body mass and length data from large samples of wild Testudo graeca, T. hermanni and T. marginala in Greece were used to assess body mass condition. Mass-length relationships differed significantly between the sexes (females being heavier) and among the species ( T. marginata being least heavy). Mass-length relationships for each species and sex were used to calculate the condition index (Cl) log (M/M'), where M is observed mass and M' is mass predicted from length, which is equal to residuals from the regression of log M on log length. It was possible to use the empirical mass-length relationships from one population of T. hermanni to calculate Cl in other populations of substantially different adult size. The seasonal pattern of the Cl varied with latitude, with a sharper and later peak further north, and habitat, declining more in summer at a xeric coastal site. The seasonal patterns of Cl in T. graeca and T. marginala were similar, with sharper and later peaks compared to T. hermanni. These seasonal patterns of Cl were related to differences in activity and food availability among species and sites. The variability of the Cl was similar in all three species, with most values between -0. 1 and +0. 1; seasonal variation was of relatively low amplitude, with a range of about 0.05 between the highest and lowest monthly means.

Keywords: condition index, season, Testudo graeca, Testudo hermanni, Testudo marginata