Shrewd shrikes and spiny shrubs: a calamity for hatchling Moorish tortoises (Testudo graeca graeca)

Cheloniansliveinasafe-boxthatoffersanef-Þcientprotectionagainstmostpredators,atleastin adults and sub-adults (Wilbur and Morin,1988). Nevertheless, in hatchlings, and to alesser extent, in juveniles the shell is soft and/ornot solid enough to resist to many predatorssuch as monitors, dogs, or birds for example(DouglasandWinegarner,1977;FitzpatrickandWoolfenden, 1978; Branch and Els, 1990; Gef-fen and Mendelssohn, 1997; Keller et al., 1998;Hill, 1999; Lagarde et al., 2001; Boarman,2002). In an open landscape, the predation onthese fragile tortoises can be severe; sometimesleaving strong marks on the population dynam-ics (Boarman, 2002). In April 2003, during aÞeld study on the ecology of Testudo graecagraeca in Morocco (Essaouira region, 31 23 N,9 42 W), we found several hatchling tortoisesimpaled on spiny shrubs ( Argania spinosa )ina typical shrike manner (Cramps and Perrins,1993). Therefore, several observations of shrike(Lanius excubitor ) were made in the study areaand even on the involved shrubs. We searchedintensively the study site and the surroundingarea (the total prospected area was 50 ha) anddiscovered a total of 25 impaled tortoises in 3spiny shrubs (respectively 17, 7 and 1 tortoisespershrub).WithanaverageShriketerritorysizeof 75 ha (Cramps and Perrins, 1993), such pre-dation may be due only to one Shrike breed-

[1]  M. Corre,et al.  SPECIES AND SEX-BIASED PREDATION ON HATCHLING GREEN TURTLES BY FRIGATEBIRDS ON EUROPA ISLAND, WESTERN INDIAN OCEAN , 2001 .

[2]  Marc Philippe.  RÉFLEXIONS SUR L'ÉVOLUTION DE LA FLORE ET DE LA VÉGÉTATION AU MAGHREB MÉDITERRANÉEN. , 2001 .

[3]  P. Quézel.  Réflexions sur l'évolution de la flore et de la végétation au Maghreb méditerranéen , 2000 .

[4]  K. Nagy.  ENERGY COSTS OF GROWTH IN NEONATE REPTILES , 2000 .

[5]  Richard Shine,et al.  Conservation biology: Restoration of an inbred adder population , 1999, Nature.

[6]  R. A. Hill.  SIZE-DEPENDENT TORTOISE PREDATION BY BABOONS AT DE HOOP NATURE RESERVE, SOUTH AFRICA , 1999 .

[7]  A. Andreu,et al.  Survival Rates and Causes of Mortality of Testudo graeca Hatchlings in Southwestern Spain , 1998 .

[8]  H. Schleich,et al.  Amphibians and reptiles of North Africa: Biology, systematics, field guide , 1996 .

[9]  K. Berry,et al.  Desert tortoises in the Mojave and Colorado deserts , 1995 .

[10]  J. Tyler.  Vertebrate Prey of the Loggerhead Shrike in Oklahoma , 1991 .

[11]  W. Branch,et al.  Prédation on the angulate tortoise Chersina angulata by the kelp gull Larus dominicanus on Dassen Island, Western Cape , 1990 .

[12]  C. Perrins,et al.  Birds of the Western Palearctic , 1978, Nature.

[13]  H. Southern,et al.  Handbook of the Birds of Europe, the Middle East and North Africa; the Birds of the Western Palearctic , 1978 .

[14]  J. Douglass,et al.  Predators of Eggs and Young of the Gopher Tortoise, Gopherus polyphemus (Reptilia, Testudines, Testudinidae) in Southern Florida , 1977 .

[15]  Carl Gans,et al.  Biology of the Reptilia , 1969 .