This project aims to explore the variation between individuals in a zoo housed group of tortoises regarding their use of the enclosure and their amount of basking behaviour. Being ectotherms, tortoises as well as other reptiles are dependent of their external thermal environments to maintain an appropriate body temperature.
Many of the species rely on behavioural responses to keep them out of harmful temperatures. On a daily basis this is mostly achieved by moving between different microhabitats. In captivity it is our responsibility to provide the animals with appropriate temperatures. When keeping reptiles, we must also create a thermal gradient to enable this crucial thermoregulatory behaviour and thus their physiological functions. When housed together with conspecifics all individuals must be given the same opportunity to perform this behaviour, i.e. access to a basking spot under a heat source or possibility to seek out a cooler part of the enclosure.
It is important to evaluate how the animals are using their environment or resources provided them, to be able to improve the settings and enhance the welfare of the animals. As animal welfare is measured at an individual level, there is a need to know the differences between single animals within a group. The species studied here, the radiated tortoise (Astrochelys radiata), is a rather solitary living species in the wild which leads to interesting questions about how their behaviour and use of the environment is affected when housed in a group in captivity.
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