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

Slimani,; Barje,; Bonnet, Xavier; Mouden, El Hassan El; Kaddour, K. Ben; Lagarde,

doi:10.1163/1568538053693341

Cited by 12 publications

(6 citation statements)

References 8 publications

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“…Predators include feral dogs, foxes, raptors, and other species. In west central Morocco, hatchlings of T. g. soussensis were found impaled by the Grey Shrike Lanius meridionalis, on spiny shrubs and Argan trees Argania spinosa (Barje et al, 2005).…”

Section: Discussionmentioning

confidence: 99%

“…In 2012, we carried out a short multiple mark-recapture biweekly series from late February to mid-May to assess the spring final population size. We referred to the first initial population size estimate obtained in spring 2003 for the same population as in Ben Kaddour et al (2005) to highlight its demographic trend. We established the mean population structure from year-round sampling during 27 to 43 days per year in 2011 and 2012.…”

Section: Sampling Methodologymentioning

confidence: 99%

“…We established the mean population structure from year-round sampling during 27 to 43 days per year in 2011 and 2012. We compared the obtained structure to those reported for the same population in 2001 (Znari et al, 2005) and 2003(Ben Kaddour et al, 2005.…”

Section: Sampling Methodologymentioning

confidence: 99%

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A management plan for a declining population of the Souss valley tortoise in an arid steppe-land of west-central Morocco

Hichami

Znari²

2021

bah

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The endangered Moorish tortoise Testudo graeca is the unique terrestrial chelonian species in North-west Africa. In west-central Morocco, the endemic subspecies, the Souss valley tortoise T. g. soussensis, occupies semi-arid to arid low-quality habitats, and is subject to serious threats. A long-term mark-recapture programme from 2001 to 2012 allowed estimating population size and structure, sex ratio, and survivorship in one of the well-known populations in a degraded and overgrazed arid steppe-land of west-central Morocco. Spring population size considerably decreased to more than half in less than 10 years, with a mean density lower than 3 ind.ha-1 in 2012 compared to its last known density estimat-ed in 2003. In spring 2012, the population structure exhibited an unbalanced male-biased sex ratio (61:39) and a scarcity of juveniles (<5%). We identified five major conservation problems in the study area: (i) habitat destruction and overgrazing; (ii) over-collecting of tortoises for pet trade , iii) direct dis-turbance; iv) tortoise handling mostly for field research, and v) increased extinction risk due to the small population size. We carried out a population viability analysis using the VORTEX software based on published and obtained data on population and life history parameters. With no management action, the population will go extinct during the forthcoming 40 years after the last estimate. The most efficient management option for a long-term persistence of the population would be reducing the nest and neo-nate mortality by 90%. To attenuate the impact of the threatening factors, we developed a management plan that includes population reinforcement and habitat restoration options.

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Section: Discussionmentioning

confidence: 99%

Section: Sampling Methodologymentioning

confidence: 99%

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A management plan for a declining population of the Souss valley tortoise in an arid steppe-land of west-central Morocco

Hichami

Znari²

2021

bah

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“…Turtles are reported occasionally and, when present, typically at a low frequency in the diet of predatory birds (e.g., Malan and Branch 1992; Tzankov and Milchev 2014; Walsh and Heinrich 2015). In some apparently exceptional cases, turtles are major prey items for avian predators (e.g., raptors, Clark 1986; gull, Branch and Els 1990; shrike, Barje et al 2005; Georgiev 2009; Gil-Sánchez et al 2022; Milchev 2022). Experimental evidence shows that hatchling turtles can experience size-specific mortality by avian predators (Janzen et al 2000).…”

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confidence: 99%

Hyperpredation of Freshwater Turtles and Tortoises by Subsidized Corvids

Moldowan

2023

Herpetological Monographs

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Subsidized predators are animals whose populations proliferate through association with humans. As subsidized predators, birds in the family Corvidae (Corvus spp., crows and ravens) pose an additive mortality threat to turtle eggs, juveniles, and, in some cases, adults. In this synthesis, I (1) review published and unpublished case studies of corvids as predators of chelonians, (2) examine regional population trends of corvids relative to the status of co-occurring chelonian species, and (3) evaluate our current understanding of subsidized corvids as threats to chelonians. Hyperpredation of chelonians by corvids is geographically widespread, locally severe where and when predation occurs, facilitated by anthropogenic subsidies (e.g., food, water, and perching, nesting, and roosting sites) and linear corridors (e.g., roads, electrical infrastructure), commonly associated with nesting corvids as predators, and co-occurring with corvid population increases. Hyperpredation by corvids appears to affect demographically sensitive stages of chelonian populations (juveniles and reproductive females) and very likely has long-term detrimental consequences given the slow life history of chelonians. The threat posed to chelonian populations by subsidized corvids is more widespread than currently recognized on the basis of substantial regional increases in corvid populations, the underreporting of predation observations, and the broad geographic areas over which hyperpredation of chelonians is occurring.

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“…Predation. -In southern Morocco, the Great Grey Shrike Lanius excubitor is an important predator of juveniles of T. g. graeca (below 3.5 cm SCL) (Barje et al 2005). In southern Spain (T. g. whitei), most of the depredated specimens are also juveniles, usually <4 yrs old (Ballestar et al 2006).…”

mentioning

confidence: 99%

Testudo graeca Linnaeus 1758 (Western Subspecies Clade: Testudo g. graeca, T. g. cyrenaica, T. g. marokkensis, T. g. nabeulensis, T. g. whitei) – Mediterranean Spur-thighed Tortoise, Moorish Tortoise, Libyan Tortoise, Moroccan Tortoise, Tunisian Tortoise, Souss Valley Tortoise

Escoriza,

Díaz-Paniagua,

Andreu

et al. 2022

Chelonian Research Monographs

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The western subspecies clade of the Mediterranean Spur-thighed Tortoise, Testudo graeca (Family Testudinidae) is comprised of small to medium-sized subspecies (maximum straight carapace lengths [SCL] <25 cm) native to northern Africa and southwestern Europe. In North Africa, Testudo graeca occurs in Mediterranean climates from humid to arid. In the Iberian Peninsula, it is restricted to subhumid, semi-arid, and arid regions. In North Africa, it reaches an altitude of 2090 m in the Haut Atlas (Morocco); in the Iberian Peninsula, it occurs at low elevations below 500 m. Testudo graeca is characterized by the presence of two spurs on the thighs, which are present in all subspecies except in 23% of specimens of T. graeca graeca. Adult females are on average larger (mean SCL = 15.5 cm, males mean SCL = 13.5 cm) and heavier than males (females mean body mass = 689 g, males mean body mass = 442 g). Females have proportionately shorter tails than males. Females produce 1-4 clutches of 1-8 eggs annually between April and July. The annual survival rate of adults is very high; it is estimated at over 90% in southern Spain. Population stability depends mainly on adult survival. The species is still relatively common and widespread in much of North Africa. However, European populations are endangered and in steep decline. In North Africa, the main threats to T. graeca are illegal collection for domestic and some international trade, degradation of habitats by overgrazing, and urbanization. In Europe, populations are threatened by habitat loss and fragmentation of populations. In Northern Africa and southwestern Europe, there is a strong tradition of collecting individuals to be kept in gardens. In Mallorca and southeastern Spain, several captive breeding projects are being carried out to reintroduce specimens in regions where the species has been extirpated. distribution. − Algeria, Libya, Morocco, Spain, and Tunisia. Introduced since historic times in the Balearic islands of Spain and western Sardinia, Italy.

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

Cited by 12 publications

References 8 publications

A management plan for a declining population of the Souss valley tortoise in an arid steppe-land of west-central Morocco

A management plan for a declining population of the Souss valley tortoise in an arid steppe-land of west-central Morocco

Hyperpredation of Freshwater Turtles and Tortoises by Subsidized Corvids

Testudo graeca Linnaeus 1758 (Western Subspecies Clade: Testudo g. graeca, T. g. cyrenaica, T. g. marokkensis, T. g. nabeulensis, T. g. whitei) – Mediterranean Spur-thighed Tortoise, Moorish Tortoise, Libyan Tortoise, Moroccan Tortoise, Tunisian Tortoise, Souss Valley Tortoise

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