The predation of young tortoise is considered a major cause of mortality for many tortoise species. The predation by common ravens has been identified as being responsible for significant decreases in tortoise populations. Mediterranean spur-thighed tortoise hatchlings and juveniles in Maamora forest (Morocco) were studied in order to describe the size/age class predation of common ravens on young tortoises and infer the drivers of predation risk and population abundance. The results showed a high level of predation on young tortoises (<75 mm carapace length) attributed to ravens in areas with low vegetation cover, representing 100% of the cases of mortality (n = 147), but it was moderate in covered areas (n = 19), representing 12-27%. The population structure of living juveniles differed significantly between covered and uncovered areas, thus suggesting that raven predation might modify juvenile population structure. Finally, N-mixture models showed a positive relationship between (i) bare cover and tortoise detectability that is only evidenced when the plot is far from a perch and (ii) population abundance and shrub species-richness, being higher in uncovered areas. Our results improve the knowledge on predation and survival on this critical stage in life, which is crucial for the conservation of the Mediterranean spur-thighed tortoise. Tortoise populations are characterised by high adult survival and low recruitment rates, which probably influence their demographic dynamics 1. The lack of reliable information on recruitment complicates evaluations of the real importance of young individuals as regards population demography 2. In this respect, threats that limit recruitment bouts may have an important regulatory effect on population dynamics 3 , especially when these threats continue over long periods of time (e.g. 4). Hatchlings and juveniles are more vulnerable than adults owing to their smaller size and higher susceptibility to environmental conditions, such as the temperature or rain, which affect their physiology, but also to vegetation cover, which influences thermoregulation, the availability of food and the risk of predation 3,5,6. Indeed, the low temperature and high rains of winter 2,7 and the high temperature of summer 8,9 are considered some of the most common causes of mortality in hatchlings. The predation of young tortoises-their shell is soft or not sufficiently solid to protect them from predators-by mammals 7,10,11 and birds 12-14 is also considered a major cause of mortality in many tortoise species, which was particularly studied in North America 7,10,12,15,16. The common raven Corvus corax is considered to be one of the most relevant predators of tortoises and is responsible for 70-91% of the mortality of desert tortoises Gopherus agassizii 4,13,17. Both single individuals and breeding pairs have been identified as responsible for significant decreases in tortoise populations, also in addition to modifying population structure by affecting juvenile size/age classes. 12,18,19 Indeed, its hig...

Online enhancement: appendix. Dryad data: http://dx.doi.org/10.5061/dryad.g4p92.abstract: Ecosystem functioning depends on nutrient cycles and their responses to abiotic and biotic determinants, with the influence of evolutionary legacies being generally overlooked in ecosystem ecology. Along a broad elevation gradient characterized by shifting climatic and grazing environments, we addressed clines of plant N and C : N content and of d 13 C and d 15 N in producers (herbs) and in primary (grasshoppers) and secondary (birds) consumers, both within and between species in phylogenetically controlled scenarios. We found parallel and significant intra-and interspecific trends of isotopic variation with elevation in the three groups. In primary producers, nutrient and isotope distributions had a detectable phylogenetic signal that constrained their variation along the environmental gradient. The influence of the environment could not be ascribed to any single factor, and both grazing and climate had an effect on leaf stoichiometry and, thus, on the resources available to consumers. Trends in consumers matched those in plants but often became nonsignificant after controlling for isotopic values of their direct resources, revealing direct bottom-up control and little phylogenetic dependence. By integrating ecosystem and mechanistic perspectives, we found that nutrient dynamics in food webs are governed at the base by the complex interaction between local determinants and evolutionary factors.

Collection for the pet trade has been considered one of the major threats to the Mediterranean spur-thighed tortoise Testudo graeca, since it modulates the size and structure of the species’ populations and, therefore, their demography. Maamora forest is one of the most suitable habitats for this species. The proximity of the forest to Rabat indicated the possibility of these tortoise populations being particularly sensitive to over-collecting. Population demography was studied in four populations, in protected and unprotected areas in Maamora forest. The results showed significant differences as regards population size and structure between protected and unprotected areas. They specifically highlighted: i) higher density (23-17 indiv · ha−1) balanced populations in the protected areas, in which young adults were predominant, ii) a higher body condition in the protected areas, especially the females, and iii) a low density (5.5 ind · ha−1) more unbalance population in the unprotected areas, in which older females and younger males were predominant. In addition, a survey carried out by interviewing local adults () showed that most people owned tortoises (61%, ), mainly juveniles (65%, ). The respondents stated that their tortoises had been captured in the forest (68%, ). Maamora forest is home to one of the highest density populations of Mediterranean spur-thighed tortoises documented to date, and its conservation is essential if this species is to be maintained. Our social survey suggested that one of the challenges is to change the social perception of the Mediterranean spur-thighed tortoise as a pet and highlight its intrinsic ecological value.

Chelonians are among the animal groups with the poorest conservation status. Since tortoises are long-lived species that need very long time to reach sexual maturity, they are extremely vulnerable to human pressure. Despite their endangered status, there are no common strategies for the development of conservation actions. At the “Mediterranean workshop to develop tortoise conservation strategies”, scientists, conservation associations, environmental managers, IUCN advisers and CITES inspectors met in October 2019 in Alicante (Spain). The aims were to update the diagnosis of the conservation status of the Hermann’s tortoise (Testudo hermanni) and the spur-thighed tortoise (Testudo graeca) and to suggest strategies that guarantee their preservation at the Mediterranean Region. The main conclusions are summarized by: i) Mediterranean tortoises are wild endangered species that must be protected in, and together with, their natural habitat. Their main threats are habitat loss and fragmentation and pet trade, but we should also pay attention to wildfires, spread of diseases, the introduction of exotic species or lineages and climate change. ii) Long-term efforts and stablished protocols are needed to accurately diagnose and monitor the conservation status of wild populations, as well as flows among captive and wild animals. iii)  Tortoise trade should be banned because it threatens the conservation of wild populations of tortoises. Illegal practices related to tortoises should be decidedly persecuted. People should consider tortoises as wild animals that are endangered and deserving of protection. It is possible to enjoy them by responsibly observing them in their habitat. iv) Tortoises may carry pathogens or parasites and their sanitary status cannot be fully assessed. They should always be considered potential vectors of tortoise diseases and of zoonosis. Hygiene protocols should be implemented when managing them. v) The researchers attending this workshop aimed to develop a scientific network for the long-term monitoring of graeca and T. hermanni populations in the Mediterranean Region. They will need the support from public administrations.