The ecology of a Mediterranean tortoise (Testudo hermanni): a declining population

Abstract

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.

Sex divergence in space utilisation in the steppe tortoise (Testudo horsfieldi)

“…Our study shows that the home range of the steppe tortoise (18 ha, using the MCP method) is noticeably large when compared with that of other Testudinidae species; all of which have a home range of only a few hectares (Rose and Judd 1975;Bertram 1979;McRae et al 1981;Stubbs and Swingland 1984;Naulleau 1988;Calzolai and Chelazzi 1991;Diemer 1992;Smith 1995;Hailey and Coulson 1996;Huot-Daubremont 1996;Smith et al 1997).…”

Habitat Selection by the Spur-thighed Tortoise Testudo graeca in a Multisuccessional Landscape: Implications for Habitat Management

“…The preference of T. graeca for low cover values has also been indicated by other authors (Wright et al 1988, Willemsem 1991. The strong selection for non-irrigated croplands could also be due to its role in egglaying, as is the case in other Testudo populations (Stubbs and Swingland 1984;Swingland and Stubbs 1985). On the other hand, it has been shown that the ecotones between crops and natural vegetation areas are optimum places for thermoregulation in the black rat snake (Blouin-Demers and Weatherhead 2001a, b), because they contain basking places near shadier areas where animals can cool down.…”

Home Range of the Spur-Thighed Tortoise, Testudo graeca (Testudines, Testudinidae), in the National Park of El Kala, Algeria

“…Our results are comforted by those of (Mazzotti et al, 2002) who attributed the Larger home ranges of Testudo hermanni which occur in northern Italy (4.6 ha in males and 7.4 ha in females) to food scarcity in this area. Th e high selection for cultivated land could also be due to their role in laying eggs, as is the case for other populations of Testudo graeca (Stubbs, Swingland, 1984). Th e vegetation structure is also an important factor because it infl uences microhabitats by controlling the penetration of the sunlight, which aff ects the microclimate at the soil.…”

“…Unauthenticated Download Date | 5/9/18 7:32 PM ment criteria of Stubbs (Stubbs, Swingland, 1984). Th e body mass of the tortoises was measured by a digital balance (precision ± 1 g).…”