Field techniques used in recent studies of the population ecology of European tortoises are discussed. An efficient marking system suitable for large sample sizes is described. The dual problems ofageing adults and sexing juveniles are highlighted. The relative merits of sampling techniques are dependent on habitat and population density. Mark-recapture techniques are most suitable when sampling is conducted within a grid system which enables results to be stratified, allowing for differential ease of location. However, grid sampling is only practical where tortoise densities are high. At low density sites, or for brief surveys, recording numbers observed per man hour along random paths is the most convenient method, but allowances must be made for differential observer skill. Existing sampling methods bias against finding inactive animals and where these form a large proportion of the population, sample size is strongly influenced by habitat type.

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In France, wild tortoises occur at low densities (< 3/ha) in the mixed forest and maquis of the Massif des Maures. In an evergreen oak forest with scattered, traditional cultivations, distinct subpopulations still exist at relatively high density (> 10/ha). The population structure is heavily skewed in favour of old adults and recruitment is low. The population is declining due to habitat loss, both from fire and through the decline in traditional horticultural practices, leading to a reduction in nest site availability. The increase in nest density in the few suitable sites remaining leaves the eggs highly vulnerable to predation and losses of over 90% cannot be sustained. The active season is from March to November, but there is evidence of some activity during the hibernation period. Adult males maintain small, fixed home ranges, while females undertake distinct migrations to and from nesting sites in the spring and can switch to new home ranges. Juveniles are sedentary up to the age of 4 or 5 years, after which they may wander considerable distances in no particular direction, until the onset of sexual maturity. Sex ratio does not differ significantly from parity within any age cohort.

A three‐year study on reproduction in wild populations of Testudo hermanni has shown that: (a) sexual activity occurs between March and October, except the nesting season (May and June), and is most frequent in August and September, (b) tortoises are promiscuous in their mating habits, there is no evidence of mate selection in relation to size, (c) nest site selection is correlated to ground temperature and nesting itself mainly occurs in the early evening before dark, when the ground temperature characteristics are most indicative of a specific site's relative temperature, (d) incubation takes about three months and is probably temperature dependent, (e) most nests are preyed upon by mammalian predators within a few days after laying (> 90% being destroyed), the main cue being the smell of the eggs, (f) average clutch size in Greece is higher than in France, while mean egg weight in France is higher than in Greece, and there is no strong relationship between body size or weight and egg or clutch weight in either country, (g) in contrast to other studies, there is no apparent correlation between rainfall and reproduction parameters, (h) some females nest in successive years, and more than once in a year, with a laying interval of 10–20 days, (i) mean size of sexually active individuals is not significantly different from the mean size of adults, although nesting females are significantly bigger; the minimum size for sexually active males is about 120 mm and for females 130 mm. The discussion examines these observations in an evolutionary context.

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