Sexual disparity in activity patterns and time budgets of angulate tortoises (Chersina angulata) on Dassen Island, South Africa

Abstract

Behavioural frequencies and time budgets for male and female Chersina angulata were recorded in spring, September 2004. The daily activity of the population was 10.51 ± 0.42 h (mean ± CI), but individual males and females were in the open for 2.57 ± 1.12 h and 1.58 ± 1.44 h, respectively. Both sexes spent nearly 3.5 h per day basking with 90% of the basking time in the cover of sparse vegetation. Feeding and walking were the most frequent active behaviours. The activity pattern of the sexes differed between 10:00 and 12:00 in the morning when males spent more time out of cover on active behaviours, particularly feeding, than females did. The daily activity pattern of the population peaked between 10:00 and 12:00, reflecting the activity pattern of the more active sex, males. Females were out of cover, active, and feeding at higher temperatures than were males. The high temperatures  probably allowed  females to complete activities more efficiently, reducing their exposure time and  predation risk. Although fighting and mating represented small fractions of male time budgets, the extended physical presence through walking and feeding may help  males to establish dominance hierarchies and enhance mating success.

Key words: activity pattern, behaviour, temperature, thread-trailing, time budget, tortoise.