Seasonal Shelter Selection by Leopard Tortoises(Geochelone pardalis)in the Franklin Nature Reserve, Free State, South Africa

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Abstract

- Seasonal habitat utilization, refugia selection, and sheltering behavior by the leopard tortoise(Geochelone pardalis)was investigated over a 24-month period (September 1990-September 1992) in the Franklin Nature Reserve, South Africa. The study area was located on Naval Hill, a dolerite and shale mesa which provided diverse topographical and vegetation aspects from which the tortoises could select habitats and refugia. Results showed that considerable shifts occurred in habitat and shelter selection between summer days, summer nights, and winter, with tortoises predominantly utilizing the plateau area. This was ascribed to the availability of shelter, exposure to solar radiation, accessibility, food resources, and the presence of water. Shelters were selected to meet specific needs governed by environmental conditions at the time, with 64.6% of shelters being exclusively utilized within one of the three periods monitored. Thirty-three plant species were utilized as shelters. Tortoises selected dense shelter cover during summer days, light shelter cover or none at all for summer nights, and light shelter cover for winter. Of the latter category, 67.4% of tortoises selected < 50% cover. Day and night shelter orientation was completely random in summer. The orientation of winter shelters was predominantly westerly with light cover shelters, and within which 67.4% of tortoises remained throughout winter. Under the cold conditions encountered on Naval Hill this appeared to be the best-suited survival strategy and provided the best conditions for tortoises to build up and retain sufficient heat during the day in order for them to maintain a temperature above that of ambient through most of the night.

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