The ecology of a Mediterranean tortoise (Testudo hermanni): Reproduction

Abstract

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.

Seasonal habitat preference by the flagship species Testudo hermanni: Implications for the conservation of coastal dunes

“…We focused on the relationships between the flagship species T. hermanni and the coastal EU habitats. Our results confirmed that climate and behavioral patterns play a crucial role in habitat use and preference by ectothermic species, especially tortoises [15,16,21,[47][48][49][50][51]. Hermann's tortoise broadly selected patchy areas [21] where close vegetation alternates with open areas with a specific seasonal pattern that was assessed here for the first time.…”

“…The need to escape the high summer temperatures at the onset of the pre-estivation phase [14][15][16]47,48] is the main factor that most likely influenced the exclusive preference for the close vegetation of sclerophyllous scrubs (EU cod. 2260) observed in July.…”

Avaliação da predação de Podocnemis expansa e Podocnemis unifilis (Testudines, Podocnemididae) no rio Javaés, Tocantins

“…Segundo Swingland & Stubbs (1985), a vulnerabilidade dos ninhos à predação, o sucesso da eclosão e o sexo dos recém-eclodidos são todos dependentes da seleção do local de desova. Diversos fatores podem influenciar a taxa de predação, dentre os quais, o ambiente de nidificação, a disponibilidade de predadores e as características e a densidade das covas (Burger, 1976;Burke et al, 1998;Pezzuti & Vogt, 1999;Ferreira Jr., 2003).…”

“…Segundo Swingland & Stubbs (1985) os jabutis gigantes (Geochelone gigantea e Geochelone elefhantopus) possuem apenas um predador de ninhos, um grande caranguejo terrestre (Birgus latro).…”

“…Segundo Swingland & Stubbs (1985), a perda de ovos através da predação é menos devastadora em longo prazo, do que a perda através da colocação do ninho em um local inapropriado, tanto em termos de temperaturas muito altas ou muito baixas para a incubação ocorrer adequadamente, ou em termos da razão sexual.…”