Shrewd shrikes and spiny shrubs: a calamity for hatchling Moorish tortoises (Testudo graeca graeca)
Résumé
Chelonians live in a safe-box that offers an efficient protection against most predators, at least in adults and sub-adults (Wilbur and Morin, 1988). Nevertheless, in hatchlings, and to a lesser extent, in juveniles the shell is soft and/or not solid enough to resist to many predators such as monitors, dogs, or birds for example (Douglas andWinegarner, 1977; Fitzpatrick and Woolfenden, 1978; Branch and Els, 1990; Geffen and Mendelssohn, 1997; Keller et al., 1998; Hill, 1999; Lagarde et al., 2001; Boarman, 2002). In an open landscape, the predation on these fragile tortoises can be severe; sometimes leaving strong marks on the population dynamics (Boarman, 2002). In April 2003, during a field study on the ecology of Testudo graeca graeca in Morocco (Essaouira region, 31◦23N, 9◦42W), we found several hatchling tortoises impaled on spiny shrubs (Argania spinosa) in a typical shrike manner (Cramps and Perrins, 1993)