Xavier Bonnet - Academia.edu (original) (raw)

Papers by Xavier Bonnet

HAL (Le Centre pour la Communication Scientifique Directe), 2021

Bulletin of Environmental Contamination and Toxicology, Jun 8, 2018

We assessed trace elements concentration in European pond turtle (Emys orbicularis) from Brenne N... more We assessed trace elements concentration in European pond turtle (Emys orbicularis) from Brenne Natural Park (France). We sampled road-killed turtles (N = 46) to measure the concentrations of 4 non-essential (Ag, Cd, Hg, and Pb) and 10 essential (As, Co, Cr, Cu, Fe, Mn, Ni, Se, V, and Zn) elements in muscle, skin, liver and claws. Body size or sex did not influence the concentrations of most elements; except for Hg (liver, skin and claws) and Zn (muscle) which increased with body size. We found relatively high concentrations of Hg and Zn, possibly linked to fish farming. This result deserves future investigations to evaluate possible ecotoxicological effects on E. orbicularis.

European Journal of Wildlife Research, May 19, 2022

Journal of Zoology, Mar 22, 2011

Temperature influences ectotherm fitness by affecting physiological performance. Terrestrial rept... more Temperature influences ectotherm fitness by affecting physiological performance. Terrestrial reptiles behaviourally regulate their body temperature by selecting particular microhabitats or activity periods. In temperate climates, thermal constraints make precise thermoregulation costly. Theoretical models of thermoregulation predict that species in cool environments should exhibit lower optimal temperature for performance and lower thermal preferences to minimize thermoregulatory costs. Empirical data in support of this prediction remain equivocal because several species maintain high and constant body temperatures, even in cool environments. We studied two largely sympatric colubrid snakes, Hierophis viridiflavus and Zamenis longissimus that share numerous morphological and ecological similarities, but differ markedly in thermal preference. Our objective was to quantify their thermoregulatory strategies in the field to determine how thermal preferences translate in habitat use and performance gain. The thermophilic species, H. viridiflavus, selected open microhabitats, whereas Z. longissimus, which prefers cooler temperatures, used a greater diversity of microhabitats. The two species differed markedly in their exposure levels. Hierophis viridiflavus was constrained to shuttle between sun and shade to maintain preferred body temperatures rendering it very exposed, while covered microhabitats were usually thermally compatible with the requirements of Z. longissimus. High exposure was apparently counterbalanced by higher locomotor performances in H. viridiflavus. The divergence in thermal ecology between Z. longissimus and H. viridiflavus likely reflects different trade-offs between energy gain and predator avoidance.

The Journal of Environmental Education, Jan 7, 2020

The likeability of organisms is an effective tool for conservation education. However, stimulatin... more The likeability of organisms is an effective tool for conservation education. However, stimulating the cute appeal of animals can also bolster the desire to possess them, and thus can encourage the trade in animals as pets. We assessed the perception of primary French schoolchildren (7-11 years old) for the Hermann tortoise (Testudo hermanni), a popular species endangered by illegal harvesting. Likeability for tortoises is associated with a strong willingness to protect them. Many children, however, expressed controversial attitudes toward them, such as the desire to possess a tortoise as a pet and to remove it from its natural habitat. Likeability was a significant determinant of these attitudes, and must thus be used with caution. Implementing these findings in conservation education programs should, therefore, be considered.

Wildlife Research, 2016

Context. Mediterranean areas offer a mosaic of favourable microhabitats to reptiles (e.g. open zo... more Context. Mediterranean areas offer a mosaic of favourable microhabitats to reptiles (e.g. open zones, thorny bushes) and are considered as biodiversity hotspots for these organisms. However, in these dry and hot environments, reptiles remain sheltered most of the time. They generally escape observation, posing difficulties to perform inventories. Trap sampling or rock-turning surveys commonly used to detect reptiles entail important logistical constraints, may perturb fragile microhabitats, and are not appropriate for chelonians. Alternative simple and cost-effective methods are desired. Aims. We tested the efficiency of camera trapping in a dry Mediterranean landscape, notably to detect threatened Hermann's tortoises. We tested whether small artificial freshwater ponds could attract animals in the field of view of the cameras to increase detectability. We also tested whether sand tracks survey around ponds could improve the method. Methods. We used a small number of cameras with ponds (5 in 2011, 7 in 2012), thereby maintaining low logistical costs. We randomly filled three ponds and emptied three ponds every 7 days. We set the time-lapse function of each camera with an interval of 5 min and inspected the sand tracks every 2 or 3 days. We used information from 39 radio-tracked tortoises to better estimate the detectability performances of the camera-pond system. Key results. This technique was effective to detect tortoises (n = 348 observations) and five other reptiles (among the 11 species present in the study area). Large numbers of birds and mammals were observed (n = 4232, n = 43 species at least), thereby increasing the biodiversity list of the surveyed area. We detected 28% of the radio-tracked tortoises present in the monitored area. Filled ponds were more attractive and sand track survey completed camera monitoring. Conclusions. Camera trapping associated with small ponds represent a useful tool to perform rapid inventories of the fauna in Mediterranean habitats, especially to detect the emblematic Hermann's tortoise and other cryptic reptiles (e.g. snakes). Implications. The low cost-efficiency ratio of this method allows performing multiple counting surveys, and thus may help collect robust data necessary to justify the protection of key habitats that are coveted by property developers.

Biodiversity and Conservation, Oct 16, 2017

A lack of long-term monitoring often impedes the evaluation of translocation used to reinforce po... more A lack of long-term monitoring often impedes the evaluation of translocation used to reinforce populations. Crucial questions regarding the exact timing and place of possible settlement remain unanswered. To examine these issues we radio-tracked during three years 24 tortoises (Testudo hermanni hermanni) released to reinforce a resident population impacted by fire. Individuals from the resident population (N = 20) and from a distant control population (N = 11) were also radio-tracked. More than 11,000 fixes were collected, enabling us to precisely describe movement patterns. Most translocated tortoises first dispersed ([ 500 m to [ 3000 m away) in a random direction and sometimes crossed unfavorable areas. Later, a marked shift in movement pattern, from a relatively unidirectional course to multidirectional displacements indicated settlement. Movement patterns of translocated and resident individuals became undistinguishable after settlement. Most individuals settled during the first year after release but several settled in the second year. Mean annual survival rate ([ 85%) remained within the range of the species but was lower compared to the resident (93%) and control tortoises (100%). Overall, most translocated individuals (* 63%) settled and adapted well to their novel environment. This result is essential regarding current controversies that are unfounded and that limit conservation translocations. Yet, translocation sites should be large enough and/or surrounded by secondary favorable areas to limit the mortality associated with dispersal in hazardous environments. Large numbers of individuals rescued during urbanization works may easily supply conservation translocations to reinforce fragile populations.

HAL (Le Centre pour la Communication Scientifique Directe), 2022

Translocations are important tools to mitigate anthropogenic impacts on threatened populations. H... more Translocations are important tools to mitigate anthropogenic impacts on threatened populations. However they generally suffer from a lack of feed-back; the success of translocations and methodological improvements cannot be evaluated. In 2013, we translocated 24 Hermann’s tortoises (Testudo hermanni hermanni) into a host population impacted by fire but characterized by favorable habitats. Translocated individuals originating from rescue operations were hard-released in spring (N=12) and in autumn (N=12) and radio-tracked. We also radio-tracked individuals from the host population (N=20) and from another control population (N=11). All tortoises were intensively monitored during three years; more than 11,000 fixes enabled us to precisely describe and compare movement patterns. Translocated tortoises first dispersed from the release sites into apparently random directions, sometimes crossing unfavorable surrounding habitats, and then settled into remote favorable places. This process usually required several weeks/months, but most individuals settled during the first year after release. Annual survival rate was lower (80%) for tortoises released in autumn compared to those release in spring (87%) or to resident and control tortoises (94%, 100%); these differences were not statistically significant. Mortality was essentially caused by predation. Body condition and corticosterone levels varied between sex and across seasons without effect of translocation. This close monitoring reveals that translocated individuals adapt well to their novel environment without impacting the host population. The strong initial dispersal phase should be considered for translocation: releasing sites should be large enough and/or surrounded by secondary host areas to limit mortality associated with dispersal in hazardous environments (e.g. road-mortality).

Herpetological Journal, Jul 1, 2021

Published by the British Herpetological Society Oviparous snakes deposit their egg clutches in si... more Published by the British Herpetological Society Oviparous snakes deposit their egg clutches in sites sheltered from predation and from strong thermal and hydric fluctuations. Appropriate laying sites with optimum thermal and hydric conditions are generally scarce and are not necessarily localised in the home range. Thus, many gravid females undertake extensive trips for oviposition, and many may converge at the best egg laying sites. Dispersal mortality of neonates post-hatchling is also a critical factor. Assessing the parameters involved in this intergenerational trade-off is difficult however, and no study has succeeded in embracing all of them. Here we report data indicating that gravid females of the highly mobile European whip snake, Hierophis viridiflavus exhibit nest site fidelity whereby they repeatedly deposit their eggs in cavities under sealed roads over many decades. These anthropogenic structures provide benefits of relative safety and suitable incubation conditions (due to the protective asphalted layer?), but they expose both females and neonates to high risk of road mortality. Artificial laying sites constructed at appropriate distances from busy roads, along with artificial continuous well protected pathways (e.g. dense hedges) that connect risky laying sites to safer areas, should be constructed.

bioRxiv (Cold Spring Harbor Laboratory), Jan 23, 2021

This article is licensed under the Creative Commons Attribution 4.0 License. First detection of h... more This article is licensed under the Creative Commons Attribution 4.0 License. First detection of herpesvirus and prevalence of mycoplasma infection in free-ranging Hermann's tortoises (Testudo hermanni), and in potential pet vectors

HAL (Le Centre pour la Communication Scientifique Directe), 2016

Snakes are useful in ecosystem surveys as they can act as environmental indicators and can be mod... more Snakes are useful in ecosystem surveys as they can act as environmental indicators and can be model organisms to address conservation and fundamental issues. However, researchers and managers — 24 — rarely focus on these unpopular organisms. In 2012, we initiated a Capture-Mark-Recapture study of two Mediterranean snakes on Port-Cros and Porquerolles Island to redress this taxonomic bias and to improve current knowledge of these species. We set up a network of fibrocement slabs to facilitate the capture of the snakes. During a 3 year survey, we marked a total of 174 individuals, predominantly Malpolon monspessulanus (n = 125). Although capture numbers on each island were similar, snake density is likely to be different. Many very large individuals of both species were observed on both islands. Encouragingly, the recapture rate was 20 % and 15 % for M. monspessulanus and Rhinechis scalaris respectively, demonstrating the effectiveness of the study method. We also collected the first data on body condition and growth rate for these populations. It is therefore essential to maintain this long-term survey in order to continue the collection of basic information, permitting improved monitoring of these peculiar populations of snakes. Surveys of this kind are essential to promote snakes as key bio-indicators and provide the foundation knowledge necessary for the development of educational resources.

HAL (Le Centre pour la Communication Scientifique Directe), 2021

Wilderness & Environmental Medicine, Jun 1, 2022

Herpetozoa

Snakes are ecologically and morphologically plastic organisms that exhibit extensive variations i... more Snakes are ecologically and morphologically plastic organisms that exhibit extensive variations in body size and body condition in response to environmental factors. Documenting inter-population variations is important to describe species comprehensively across their distribution range and to monitor trends over time (e.g. decreasing body condition due to alteration of habitat). Thus, we analyzed the influence of population and sex on body size and body condition in three populations of nose-horned vipers (Vipera ammodytes) in Serbia. In one population, males were larger than females (F1, 39=4.802, p=0.034), but not in the two other populations (F1, 36=0.075, p=0.786; F1, 21=0.018, p=0.893). Females exhibited higher body condition (residual values from the regression of log-body mass against log-body size) than males (F1, 90=10.444, p=0.002); this sex difference was not found in one population when analyzed separately (F1, 35=1.834, p=0.184). Moreover, we found strong inter-populati...

HAL (Le Centre pour la Communication Scientifique Directe), Dec 16, 2018

Biological Journal of the Linnean Society

Insular populations offer excellent opportunities to study the factors that influence phenotypes.... more Insular populations offer excellent opportunities to study the factors that influence phenotypes. We observed island dwarfism in a widespread snake, the nose-horned viper (Vipera ammodytes). Island vipers were ~20% smaller than mainland individuals. They also produced fewer and smaller offspring. In snakes, food availability has a positive influence on body size, fecundity and offspring size. Consequently, low energy intake is a plausible explanation for insular dwarfism. The diet of island vipers was principally represented by lizards and centipedes, whereas the most profitable prey items (e.g. rodents) were regularly found in the stomach of mainland vipers. Furthermore, the proportion of individuals captured with a full stomach and good body condition were lower on the island compared with the mainland. Thus, island vipers were likely to be experiencing permanent energy restriction, with cascading effects on adult body size and reproductive output. Large prey promotes high relativ...

HAL (Le Centre pour la Communication Scientifique Directe), 2021

Bulletin of Environmental Contamination and Toxicology, Jun 8, 2018

We assessed trace elements concentration in European pond turtle (Emys orbicularis) from Brenne N... more We assessed trace elements concentration in European pond turtle (Emys orbicularis) from Brenne Natural Park (France). We sampled road-killed turtles (N = 46) to measure the concentrations of 4 non-essential (Ag, Cd, Hg, and Pb) and 10 essential (As, Co, Cr, Cu, Fe, Mn, Ni, Se, V, and Zn) elements in muscle, skin, liver and claws. Body size or sex did not influence the concentrations of most elements; except for Hg (liver, skin and claws) and Zn (muscle) which increased with body size. We found relatively high concentrations of Hg and Zn, possibly linked to fish farming. This result deserves future investigations to evaluate possible ecotoxicological effects on E. orbicularis.

European Journal of Wildlife Research, May 19, 2022

Journal of Zoology, Mar 22, 2011

Temperature influences ectotherm fitness by affecting physiological performance. Terrestrial rept... more Temperature influences ectotherm fitness by affecting physiological performance. Terrestrial reptiles behaviourally regulate their body temperature by selecting particular microhabitats or activity periods. In temperate climates, thermal constraints make precise thermoregulation costly. Theoretical models of thermoregulation predict that species in cool environments should exhibit lower optimal temperature for performance and lower thermal preferences to minimize thermoregulatory costs. Empirical data in support of this prediction remain equivocal because several species maintain high and constant body temperatures, even in cool environments. We studied two largely sympatric colubrid snakes, Hierophis viridiflavus and Zamenis longissimus that share numerous morphological and ecological similarities, but differ markedly in thermal preference. Our objective was to quantify their thermoregulatory strategies in the field to determine how thermal preferences translate in habitat use and performance gain. The thermophilic species, H. viridiflavus, selected open microhabitats, whereas Z. longissimus, which prefers cooler temperatures, used a greater diversity of microhabitats. The two species differed markedly in their exposure levels. Hierophis viridiflavus was constrained to shuttle between sun and shade to maintain preferred body temperatures rendering it very exposed, while covered microhabitats were usually thermally compatible with the requirements of Z. longissimus. High exposure was apparently counterbalanced by higher locomotor performances in H. viridiflavus. The divergence in thermal ecology between Z. longissimus and H. viridiflavus likely reflects different trade-offs between energy gain and predator avoidance.

The Journal of Environmental Education, Jan 7, 2020

The likeability of organisms is an effective tool for conservation education. However, stimulatin... more The likeability of organisms is an effective tool for conservation education. However, stimulating the cute appeal of animals can also bolster the desire to possess them, and thus can encourage the trade in animals as pets. We assessed the perception of primary French schoolchildren (7-11 years old) for the Hermann tortoise (Testudo hermanni), a popular species endangered by illegal harvesting. Likeability for tortoises is associated with a strong willingness to protect them. Many children, however, expressed controversial attitudes toward them, such as the desire to possess a tortoise as a pet and to remove it from its natural habitat. Likeability was a significant determinant of these attitudes, and must thus be used with caution. Implementing these findings in conservation education programs should, therefore, be considered.

Wildlife Research, 2016

Context. Mediterranean areas offer a mosaic of favourable microhabitats to reptiles (e.g. open zo... more Context. Mediterranean areas offer a mosaic of favourable microhabitats to reptiles (e.g. open zones, thorny bushes) and are considered as biodiversity hotspots for these organisms. However, in these dry and hot environments, reptiles remain sheltered most of the time. They generally escape observation, posing difficulties to perform inventories. Trap sampling or rock-turning surveys commonly used to detect reptiles entail important logistical constraints, may perturb fragile microhabitats, and are not appropriate for chelonians. Alternative simple and cost-effective methods are desired. Aims. We tested the efficiency of camera trapping in a dry Mediterranean landscape, notably to detect threatened Hermann's tortoises. We tested whether small artificial freshwater ponds could attract animals in the field of view of the cameras to increase detectability. We also tested whether sand tracks survey around ponds could improve the method. Methods. We used a small number of cameras with ponds (5 in 2011, 7 in 2012), thereby maintaining low logistical costs. We randomly filled three ponds and emptied three ponds every 7 days. We set the time-lapse function of each camera with an interval of 5 min and inspected the sand tracks every 2 or 3 days. We used information from 39 radio-tracked tortoises to better estimate the detectability performances of the camera-pond system. Key results. This technique was effective to detect tortoises (n = 348 observations) and five other reptiles (among the 11 species present in the study area). Large numbers of birds and mammals were observed (n = 4232, n = 43 species at least), thereby increasing the biodiversity list of the surveyed area. We detected 28% of the radio-tracked tortoises present in the monitored area. Filled ponds were more attractive and sand track survey completed camera monitoring. Conclusions. Camera trapping associated with small ponds represent a useful tool to perform rapid inventories of the fauna in Mediterranean habitats, especially to detect the emblematic Hermann's tortoise and other cryptic reptiles (e.g. snakes). Implications. The low cost-efficiency ratio of this method allows performing multiple counting surveys, and thus may help collect robust data necessary to justify the protection of key habitats that are coveted by property developers.

Biodiversity and Conservation, Oct 16, 2017

A lack of long-term monitoring often impedes the evaluation of translocation used to reinforce po... more A lack of long-term monitoring often impedes the evaluation of translocation used to reinforce populations. Crucial questions regarding the exact timing and place of possible settlement remain unanswered. To examine these issues we radio-tracked during three years 24 tortoises (Testudo hermanni hermanni) released to reinforce a resident population impacted by fire. Individuals from the resident population (N = 20) and from a distant control population (N = 11) were also radio-tracked. More than 11,000 fixes were collected, enabling us to precisely describe movement patterns. Most translocated tortoises first dispersed ([ 500 m to [ 3000 m away) in a random direction and sometimes crossed unfavorable areas. Later, a marked shift in movement pattern, from a relatively unidirectional course to multidirectional displacements indicated settlement. Movement patterns of translocated and resident individuals became undistinguishable after settlement. Most individuals settled during the first year after release but several settled in the second year. Mean annual survival rate ([ 85%) remained within the range of the species but was lower compared to the resident (93%) and control tortoises (100%). Overall, most translocated individuals (* 63%) settled and adapted well to their novel environment. This result is essential regarding current controversies that are unfounded and that limit conservation translocations. Yet, translocation sites should be large enough and/or surrounded by secondary favorable areas to limit the mortality associated with dispersal in hazardous environments. Large numbers of individuals rescued during urbanization works may easily supply conservation translocations to reinforce fragile populations.

HAL (Le Centre pour la Communication Scientifique Directe), 2022

Translocations are important tools to mitigate anthropogenic impacts on threatened populations. H... more Translocations are important tools to mitigate anthropogenic impacts on threatened populations. However they generally suffer from a lack of feed-back; the success of translocations and methodological improvements cannot be evaluated. In 2013, we translocated 24 Hermann’s tortoises (Testudo hermanni hermanni) into a host population impacted by fire but characterized by favorable habitats. Translocated individuals originating from rescue operations were hard-released in spring (N=12) and in autumn (N=12) and radio-tracked. We also radio-tracked individuals from the host population (N=20) and from another control population (N=11). All tortoises were intensively monitored during three years; more than 11,000 fixes enabled us to precisely describe and compare movement patterns. Translocated tortoises first dispersed from the release sites into apparently random directions, sometimes crossing unfavorable surrounding habitats, and then settled into remote favorable places. This process usually required several weeks/months, but most individuals settled during the first year after release. Annual survival rate was lower (80%) for tortoises released in autumn compared to those release in spring (87%) or to resident and control tortoises (94%, 100%); these differences were not statistically significant. Mortality was essentially caused by predation. Body condition and corticosterone levels varied between sex and across seasons without effect of translocation. This close monitoring reveals that translocated individuals adapt well to their novel environment without impacting the host population. The strong initial dispersal phase should be considered for translocation: releasing sites should be large enough and/or surrounded by secondary host areas to limit mortality associated with dispersal in hazardous environments (e.g. road-mortality).

Herpetological Journal, Jul 1, 2021

Published by the British Herpetological Society Oviparous snakes deposit their egg clutches in si... more Published by the British Herpetological Society Oviparous snakes deposit their egg clutches in sites sheltered from predation and from strong thermal and hydric fluctuations. Appropriate laying sites with optimum thermal and hydric conditions are generally scarce and are not necessarily localised in the home range. Thus, many gravid females undertake extensive trips for oviposition, and many may converge at the best egg laying sites. Dispersal mortality of neonates post-hatchling is also a critical factor. Assessing the parameters involved in this intergenerational trade-off is difficult however, and no study has succeeded in embracing all of them. Here we report data indicating that gravid females of the highly mobile European whip snake, Hierophis viridiflavus exhibit nest site fidelity whereby they repeatedly deposit their eggs in cavities under sealed roads over many decades. These anthropogenic structures provide benefits of relative safety and suitable incubation conditions (due to the protective asphalted layer?), but they expose both females and neonates to high risk of road mortality. Artificial laying sites constructed at appropriate distances from busy roads, along with artificial continuous well protected pathways (e.g. dense hedges) that connect risky laying sites to safer areas, should be constructed.

bioRxiv (Cold Spring Harbor Laboratory), Jan 23, 2021

This article is licensed under the Creative Commons Attribution 4.0 License. First detection of h... more This article is licensed under the Creative Commons Attribution 4.0 License. First detection of herpesvirus and prevalence of mycoplasma infection in free-ranging Hermann's tortoises (Testudo hermanni), and in potential pet vectors

HAL (Le Centre pour la Communication Scientifique Directe), 2016

Snakes are useful in ecosystem surveys as they can act as environmental indicators and can be mod... more Snakes are useful in ecosystem surveys as they can act as environmental indicators and can be model organisms to address conservation and fundamental issues. However, researchers and managers — 24 — rarely focus on these unpopular organisms. In 2012, we initiated a Capture-Mark-Recapture study of two Mediterranean snakes on Port-Cros and Porquerolles Island to redress this taxonomic bias and to improve current knowledge of these species. We set up a network of fibrocement slabs to facilitate the capture of the snakes. During a 3 year survey, we marked a total of 174 individuals, predominantly Malpolon monspessulanus (n = 125). Although capture numbers on each island were similar, snake density is likely to be different. Many very large individuals of both species were observed on both islands. Encouragingly, the recapture rate was 20 % and 15 % for M. monspessulanus and Rhinechis scalaris respectively, demonstrating the effectiveness of the study method. We also collected the first data on body condition and growth rate for these populations. It is therefore essential to maintain this long-term survey in order to continue the collection of basic information, permitting improved monitoring of these peculiar populations of snakes. Surveys of this kind are essential to promote snakes as key bio-indicators and provide the foundation knowledge necessary for the development of educational resources.

HAL (Le Centre pour la Communication Scientifique Directe), 2021

Wilderness & Environmental Medicine, Jun 1, 2022

Herpetozoa

Snakes are ecologically and morphologically plastic organisms that exhibit extensive variations i... more Snakes are ecologically and morphologically plastic organisms that exhibit extensive variations in body size and body condition in response to environmental factors. Documenting inter-population variations is important to describe species comprehensively across their distribution range and to monitor trends over time (e.g. decreasing body condition due to alteration of habitat). Thus, we analyzed the influence of population and sex on body size and body condition in three populations of nose-horned vipers (Vipera ammodytes) in Serbia. In one population, males were larger than females (F1, 39=4.802, p=0.034), but not in the two other populations (F1, 36=0.075, p=0.786; F1, 21=0.018, p=0.893). Females exhibited higher body condition (residual values from the regression of log-body mass against log-body size) than males (F1, 90=10.444, p=0.002); this sex difference was not found in one population when analyzed separately (F1, 35=1.834, p=0.184). Moreover, we found strong inter-populati...

HAL (Le Centre pour la Communication Scientifique Directe), Dec 16, 2018

Biological Journal of the Linnean Society

Insular populations offer excellent opportunities to study the factors that influence phenotypes.... more Insular populations offer excellent opportunities to study the factors that influence phenotypes. We observed island dwarfism in a widespread snake, the nose-horned viper (Vipera ammodytes). Island vipers were ~20% smaller than mainland individuals. They also produced fewer and smaller offspring. In snakes, food availability has a positive influence on body size, fecundity and offspring size. Consequently, low energy intake is a plausible explanation for insular dwarfism. The diet of island vipers was principally represented by lizards and centipedes, whereas the most profitable prey items (e.g. rodents) were regularly found in the stomach of mainland vipers. Furthermore, the proportion of individuals captured with a full stomach and good body condition were lower on the island compared with the mainland. Thus, island vipers were likely to be experiencing permanent energy restriction, with cascading effects on adult body size and reproductive output. Large prey promotes high relativ...