The ecology of the mediterranean tortoise Testudo hermanni in northern Greece (the effects of a catastrophe on population structure and density)

Stubbs, David; Swingland, Ian R.; Hailey, Adrian; Pulford, Elizabeth

doi:10.1016/0006-3207(85)90045-x

Cited by 59 publications

(35 citation statements)

References 2 publications

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“…Given that tortoises are long-lived and late-maturing (Hailey & Willemsen 2000), eventual demographic catastrophes can be very difficult for their populations to recover from, with consequent high extinction probabilities (e.g. Stubbs et al 1985). Urban populations of tortoises should also be monitored in order to assess the effects of herbicides on their survival, given that these toxic materials are often used in agricultural areas and have been demonstrated to be extremely dangerous for T. hermanni in Greece (Willemsen & Hailey 2001).…”

Section: Discussionmentioning

confidence: 99%

Ecological modelling of habitat use and the annual activity patterns in an urban population of the tortoise,Testudo hermanni

Rugiero

Luiselli²

2006

Italian Journal of Zoology

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The Hermann's tortoise (Testudo hermanni) is increasingly threatened in Western Europe and in Italy because of habitat loss, pollution, and illegal removal of free-ranging individuals for the pet trade. Hence, the conservation and appropriate management of the various populations is mandatory, and the few remnant, isolated populations inhabiting urban parks and heavily altered landscapes may be particularly important. An urban population of Hermann's tortoises was studied by capture-mark-recapture procedures in an 'urban green area' in Rome ('Insugherata' Natural Reserve), between March 2001 and October 2005. A spatial modelling approach (logistic regression, with forward stepwise addition model) was developed to investigate which proximate landscape factors influenced the presence/absence of the tortoises. Eight different variables were considered for this model. We found that a single variable (SHRUBS, i.e. Mediterranean dry macchia-like vegetation) was positively correlated to the presence of tortoises, and one to their absence (ECOTONE, i.e. ecotone area constituted by different types of shrubs growing on a relatively wet substratum). The tortoise activity deviated significantly from the null hypothesis of an equal activity throughout the year, with the higher peaks of activity in May, June, and August, and reduced activity in March and April. The conservation implications of our study were also discussed.

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Section: Discussionmentioning

confidence: 99%

Ecological modelling of habitat use and the annual activity patterns in an urban population of the tortoise,Testudo hermanni

Rugiero

Luiselli²

2006

Italian Journal of Zoology

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“…Alyki main heath ± coastal heath, grassland and dry heath (Stubbs et al, 1985), which was burned and ploughed in 1980 and 1990 (Hailey & Goutner, 1991). Altitude 0 m.…”

Section: Altitude 650 Mmentioning

confidence: 99%

“…Data on body size (maximum straight carapace length ± SCL ± of the larger sex) and distribution (median latitude, estimated from distribution maps) are from the reviews of Ernst & Barbour (1989) and Swingland & Klemens (1989). main heath (Stubbs et al, 1985), separated from this by the entrance to the saltwater lagoon. The author of the latter account (Branch, 1989) gives a much smaller value elsewhere (114 mm in Branch, 1988) and so the value of 115mm was used here.…”

Section: Altitude 650 Mmentioning

confidence: 99%

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Variation of adult body size of the tortoise Testudo hermanni in Greece: proximate and ultimate causes

Willemsen¹,

Hailey

1999

Journal of Zoology

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Seventeen populations of T. hermanni in Greece differed substantially in mean adult body size, over a range of about one and a half times in length and three times in mass. Females were the larger sex in all populations; the degree of sexual size dimorphism did not vary with mean body size. The proximate cause of the variation of body size among populations was differences in the duration of growth, rather than egg or hatchling size or the growth rates of juveniles. The age at maturity (a) increased with body size in the 17 populations, while the Bertalanffy growth constant (k) decreased with body size. The quantities aM and M/k (where M is the instantaneous mortality rate) were invariant with body size, suggesting that differences between populations were adaptive rather than the result of short-term disturbance. Body size was greater in cooler areas, and increased with both latitude and altitude. This pattern is opposite to that found in most ectotherms (the reverse Bergmann's rule), and to that which occurs between tortoise species. Several hypotheses about the possible ultimate causes of variation of body size were rejected, including adaptation to long-term habitat disturbance (land use), character displacement, social factors, energetics, thermoregulation, r-K selection, the length of the season available for incubation, or differences in juvenile mortality. The most likely ultimate cause of size variation between sites is differences in adult mortality, the correlation with environmental temperature being through the frequency of ®res.

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“…Research demonstrates that drought affects aquatic and semi-aquatic turtle activity and behavior (Christiansen and Bickham, 1989;Anthonysamy et al, 2013;Rowe et al, 2013), stress hormones (Cash and Holberton, 2005), reproduction and emigration (Gibbons et al, 1983), and population size and survival (Lindeman and Rabe, 1990;Rees et al, 2009;Olivier et al, 2010;Leidy et al, 2016). Publications on the effects of fire on turtles are confined almost exclusively to those documenting mortality in tortoises (Stubbs et al, 1985;Hailey, 2000;Esque et al, 2002;Lovich et al, 2011a) and other terrestrial species (Ernst et al, 1995;Platt et al, 2010;Howey and Roosenburg, 2013).…”

Section: Introductionmentioning

confidence: 99%

The effects of drought and fire in the extirpation of an abundant semi-aquatic turtle from a lacustrine environment in the southwestern USA

Lovich

Quillman²,

Zitt³

et al. 2017

Knowl. Manag. Aquat. Ecosyst.

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-We documented a significant mortality event affecting a southwestern pond turtle (Actinemys pallida) population living in a lake in southern California, USA. The area around the lake was impacted by a large wildland fire in 2013 that occurred during a protracted drought. As the mortality event was still unfolding, we collected data in 2014 on water quality, demographic structure, and short-term survivorship of the population. Water quality was poor with low levels of dissolved oxygen and high salinity of up to 45.90 ppt. Many turtles were severely emaciated and coated with a pale mineralized layer on their shells and skin. Estimated survival rate was low leading to a projected 90% decline in 134 days and a high probability of extirpation within a year. The lake was dry in September 2015 with no evidence of live turtles. Necropsies and low volumetric body condition indices suggested death by starvation. Although this semi-aquatic species has the ability to aestivate in upland habitats during periods of low water or move to other nearby water bodies, it is unlikely that many were able to do so because of their extremely poor condition and the severity of the drought conditions throughout the area.Keywords: climate / evaporite / starvation / survivorship / water quality Résumé -Les effets de la sécheresse et du feu dans l'anéantissement d'un abondant vertébré semiaquatique dans un milieu lacustre du sud-ouest des États-Unis. Nous avons relevé un événement de forte mortalité affectant une population de tortues du sud-ouest (Actinemys pallida) vivant dans un lac au sud de la Californie, États-Unis. Les environs du lac ont été touchés par un grand incendie forestier en 2013 qui s'était produit au cours d'une sécheresse prolongée. Comme l'événement de mortalité continuait à se dérouler, nous avions recueilli des données en 2014 sur la qualité de l'eau et sur la structure démographique et la survie à court terme de la population. La qualité de l'eau était faible avec de bas niveaux d'oxygène dissous et une salinité élevée allant jusqu'à 45,90 ppm. De nombreuses tortues étaient gravement émaciées et revêtues d'une couche minéralisée pâle sur leurs carapaces et leurs peaux. Le taux de survie estimé était faible, ce qui a entraîné un déclin attendu de 90 % en 134 jours et une probabilité de disparition élevée dans un délai d'un an. Le lac était à sec en septembre 2015 sans aucune preuve de tortues vivantes. Des nécropsies et de faibles indices de condition corporelle volumétrique suggéraient la mort par inanition. Bien que cette espèce semi-aquatique ait la capacité d'estiver dans les habitats des hautes-terres pendant les périodes de basses eaux ou de se déplacer vers d'autres plans d'eau avoisinants, il est peu probable que beaucoup de tortues aient pu le faire en raison de leur très mauvais état et de la sévérité des conditions de sécheresse dans toute la région.

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The ecology of the mediterranean tortoise Testudo hermanni in northern Greece (the effects of a catastrophe on population structure and density)

Cited by 59 publications

References 2 publications

Ecological modelling of habitat use and the annual activity patterns in an urban population of the tortoise,Testudo hermanni

Ecological modelling of habitat use and the annual activity patterns in an urban population of the tortoise,Testudo hermanni

Variation of adult body size of the tortoise Testudo hermanni in Greece: proximate and ultimate causes

The effects of drought and fire in the extirpation of an abundant semi-aquatic turtle from a lacustrine environment in the southwestern USA

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