Temperature, activity and field sighting in the mediterranean spur-thighed or common garden tortoise Testudo graeca L

Abstract

Daylight observations on NW African and W Turkish populations of the Mediterranean spur-thighed tortoise Testudo graeca L. showed that activity, depending upon maturity, sex and size, is influenced by air temperature and sunshine. Tortoises are active above 18°C while refuge from sunshine during the middle of the day occurs above 28°C. Morning basking increases body temperature, which under glass in S England was shown to be thermoregulated at about 35°C. With movements in and out of sunshine, most heat is dissipated through the plastron. Field sighting frequency (no.man-h −1) as a relative index of abundance in low density populations is influenced by activity and behaviour type. This is discussed with regard to tortoise detection being increased by locomotory rustling and mating sounds in thick vegetation.