Seasonal and daily activity patterns of leopard tortoises (Stigmochelys pardalis Bell, 1828) on farmland in the Nama-Karoo, South Africa

Abstract

The leopard tortoise (Stigmochelys pardalis) is the largest of southern Africa’s 13 tortoise species, and occurs in a variety of habitats from arid and semi-arid areas to mesic grassveld, savanna and bushveld. Seasonal activity patterns of S. pardalis  were investigated as a function of rainfall, sex, time of day, temperature and time after sunrise on farmland in the semi-arid  Nama-Karoo, South Africa. We predicted that because of seasonal rainfall, and subsequent increase in the food available, activity patterns of leopard tortoises would vary greatly among seasons, but that the primary constraint on activity levels within a season would be ambient temperature. Type of activity, time of day that the activity was performed, and the frequency that each activity was performed, differed among seasons. There was no overall seasonal difference in the level of activity with sex, but in certain seasons and with regard to specific activities, there were significant differences between the sexes. Diel activity was primarily bimodal in summer and autumn, and unimodal in winter and spring, with nonthermoregulatory activities being performed primarily in the afternoon. There was a positive correlation between number of tortoises caught and rainfall per season, but activity levels and number of tortoises walking and feeding was not correlated with seasonal rainfall. Leopard tortoise activity behaviours   responded to ambient temperature, but results indicate that activity is also initiated by the time since sunrise.

Key words: Stigmochelys pardalis, leopard tortoise, activity patterns, activity  behaviour, Nama-Karoo Biome, time of day, season.