Organisms that produce more than one newborn at every reproductive event must choose between two ... more Organisms that produce more than one newborn at every reproductive event must choose between two options with respect to their reproductive output: to produce a few large or many small young. The decision will be influenced by the spectrum of prey sizes available to young. The ladder snake (Rhinechis scalaris), a heavy-bodied Mediterranean colubrid, is well suited for the study
Cientos de miles de reptiles y anfibios mueren en los aljibes de uso ganadero, según un equipo in... more Cientos de miles de reptiles y anfibios mueren en los aljibes de uso ganadero, según un equipo internacional que ha trabajado en el suroeste de Marruecos. En más de ochocientos aljibes visitados, las especies que quedan atrapadas superan la treintena, algunas amenazadas. El siguiente paso será proponer medidas correctoras.
In many vertebrates, foraging mode (active versus sit-and-wait) is tied to some traits of their n... more In many vertebrates, foraging mode (active versus sit-and-wait) is tied to some traits of their natural history such as morphology, type of prey, rate of food acquisition, and survival rate. We explore the correlates between some morphological traits of a Mediterranean colubrid and its feeding ecology and the predation risk, by comparing data on teeth number, tail damage, and diet.
Questionnaires are important tools for assessing attitudes regarding conservation issues. However... more Questionnaires are important tools for assessing attitudes regarding conservation issues. However, they are not easily comparable and their reliability has been insufficiently assessed. We examined factors influencing responses to open-and closed-ended questions about animal conservation to more than 600 schoolchildren (9 years old on average). We analysed the level of understanding, controllable (e.g. sample size) and less controllable factors (e.g. affectivity). Most children responded appropriately to the questions, but subtle changes in the phrasing influenced the answers. Affectivity towards endearing species and spontaneity also influenced the responses whereas small sample sizes ( 50 children) provided relatively stable patterns. Overall, we suggest that standardization of questionnaires administered over large spatial and time scales is needed to accurately assess children's attitudes towards conservation issues.
Predator-prey interactions are key factors in the evolution of defensive tactics. In snakes, shy ... more Predator-prey interactions are key factors in the evolution of defensive tactics. In snakes, shy organisms from which direct evidence of predator-prey interactions is difficult to obtain, injuries are potential indicators of both the nature and frequency of interactions. We studied the incidence of tail breakage and body scarring in the ladder snake, Rhinechis scalaris, an actively foraging Mediterranean snake, and tested several hypotheses that link body injuries and snake life-history traits, mainly under sexual and ontogenetic aspects. Evidence is presented supporting an ontogenetic shift in the frequency of tail breakage, with the incidence of tail loss increasing as a logistic function of snake size. We relate this finding to the adaptive significance of ontogenetic shifts in dorsal pattern and the reaction of snakes to approaching predators; small individuals are more likely to remain immobile than are medium to large individuals, the former aided by a concealing dorsal pattern with transverse lines, and the latter by a striped pattern. This species exhibited sex differences in body scarring but not in tail breakage, nor did we encounter evidence to suggest that snakes experience multiple tail breaks over time, thus failing to support the sexual difference and multiple tail breakage hypotheses. Moreover, we failed to find a lower frequency of body scarring than tail breakage; hence, our results do not afford evidence that frequency of tail breakage represents an inefficiency of predators in catching or dispatching ophidian prey.
Reproductive characteristics of the Viperine Snake, Natrix maura (Linnaeus, 1758), in the De- pre... more Reproductive characteristics of the Viperine Snake, Natrix maura (Linnaeus, 1758), in the De- presión de Granada (Southeastern Spain).- We studied 267 specimens of the Viperine snake, Natrix maura, from the Depresión of Granada (southeastern Iberian Peninsula) in order to determine size at sexual maturity, reproductive cycle, and fat body cycle in both sexes, as well as clutch size and laying
Zoologischer Anzeiger - A Journal of Comparative Zoology, 2013
Tail breakage can help reptiles to escape from predators. Despite the immediate advantage for sur... more Tail breakage can help reptiles to escape from predators. Despite the immediate advantage for survival, tail loss can also entail negative consequences. We have examined some potential costs associated to tail breakage in the colubrid snake Rhinechis scalaris (Schinz, 1822), a medium-sized terrestrial species with a high incidence of tail breakage (40.7% in the largest individuals). Tail damaged individuals were not smaller than undamaged individuals, fat-body levels (a measure of body condition) did not differ between tail damaged and tail undamaged individuals, and no relationship was found between the remaining pairs of subcaudal scales (a measure of tail-loss severity) and fatbody level in specimens with damaged tails. All results failed to support a cost in terms of overall body condition associated with tail breakage. The tail is of low importance for locomotion, there are no vital morphological structures in the tail necessary for a healthy physiology, and snakes undergo non regenerative tail loss.
Arid regions are increasingly being anthropogenically altered. In the north-western Sahara, a gro... more Arid regions are increasingly being anthropogenically altered. In the north-western Sahara, a growing road network facilitates the use of habitats adjacent to roads. In regions where livestock is the traditional and main economic resource, local people are currently building numerous water cisterns for watering livestock, leading to an increase in the extent of pasturing of domestic livestock. Cisterns may attract desert vertebrates and act as death traps for species with already sparse populations in these arid areas. This paper is the first to examine the impact of cisterns as lethal traps for amphibians and reptiles in the Sahara, using a survey of 823 cisterns in south-western Morocco to identify and quantify species affected. Four amphibians and 35 reptiles were trapped in cisterns, some of which were listed as threatened. At least 459 017 individual amphibians and reptiles were trapped annually within the study area. The low productivity and low population densities of terrestrial vertebrates in this arid region suggest cisterns have a substantial impact upon amphibian and reptile species. As cistern construction is increasing, management actions are required to mitigate this impact on the herpetological community.
Two spermatogenetic cycles, vernal and aestival, have been described in temperate colubrid snakes... more Two spermatogenetic cycles, vernal and aestival, have been described in temperate colubrid snakes. In both cycles, mating occurs in the spring, although vernal species produce spermatozoa in spring, just before mating, while aestival species use spermatozoa produced the previous summer. In this study, we describe the reproductive cycles of male and female Malpolon monspessulanus (Colubridae), and compare them to previously published cycles of five other snake species, four vernal and one aestival, inhabiting the same area. We also examine the consequences of both spermatogenesis cycles over the entire reproductive processes of male and female snakes in the south-eastern Iberian Peninsula. Vernal species mate later than do aestival species, as males must produce spermatozoa just prior to mating. However, vernal species are able to condense spermatogenesis and vitellogenesis processes, hence undertaking oviposition at the same time as aestival species. Here we discuss advantages of accomplishing the entire reproductive cycle in one (vernal species) or two (aestival species) calendar years. We also found that mature male M. monspessulanus exhibit decreased testes volume relative to body size. Large testes are expected in scenarios of sperm competition. The mating system of M. monspessulanus (territoriality, mate guarding, male-male combat) does not suggest sperm competition, hence it may be more advantageous for males of this species to invest in body size than in testes size.
It is difficult to measure predation risk for secretive animals such as snakes. The frequency of ... more It is difficult to measure predation risk for secretive animals such as snakes. The frequency of tail breakage has been suggested as a parameter for measuring predation risk in these reptiles. Consequently, we hypothesise that tail breakage frequency is expected to vary intraspecifically between populations submitted to different numbers of predators, probably, to different predation risk. The colubrid snake Natrix maura has adapted to living on fish farms, which are protected from aerial predators by wire mesh, so that these farms provide researchers with a predator-exclusion scenario. We measured tail breakage frequency in this snake on a fish farm and compared the results with data from three populations in natural settings in the Iberian Peninsula under assumed higher predation risk from a complete community of predators. A logistic regression analysis demonstrated that snake body size and predator exclusion affected the probability of tail breakage, while sex had no effect. We found an ontogenetic increase in the frequency of tail breakage, a general pattern in snakes and, notably, marked differences between populations according to predation risk: snakes from the fish farm showed a low frequency of tail breakage (5.1%), whereas snakes from natural habitats, with five-fold more potential predators on average, demonstrated a higher frequency of tail breakage (18.7%). We conclude that tail breakage frequency is a reliable indicator of predation risk in this aquatic snake.
The viperine snake Natrix maura is a common water snake, which forages on aquatic prey such as fi... more The viperine snake Natrix maura is a common water snake, which forages on aquatic prey such as fish and frogs in Western Mediterranean water bodies. Female viperine snakes collected from three populations at the Iberian Peninsula during the vitellogenesis period were compared. Mean clutch size and range, as well as the slope of the regression between body size and clutch size, did not show differences between populations. In contrast, mean size of enlarged follicles of females collected in May from the Ebro Delta proved significantly smaller than those of females from the Matarranya River (50 km far) and the Granada Depression (500 km far). There were no differences in climatic conditions between areas. However, seasonal variation in food availability was significantly different in the Ebro Delta. In this area, the rice fields are dry in early spring as men control the water flow, and prey are not available. This energetic constraint induced female viperine snakes to adjust reproductive timing according to seasonal availability and to delay vitellogenesis for at least one month. By contrast, other Mediterranean populations exhibited a rather high prey availability from early spring (e.g. Matarranya River), females being in good condition in this season and consequently vitellogenesis starting earlier than in the Ebro Delta. This study illustrates a new case of reproductive plasticity in snakes.
For cultural reasons and due to the narrow vision of environmental policy makers, most conservati... more For cultural reasons and due to the narrow vision of environmental policy makers, most conservation efforts focus on a few charismatic species and consequently neglect the majority of others under threat; many unpopular species are even killed in large numbers with little concern. Redressing this bias through educational programs is therefore important. Snakes are unpopular animals; they suffer from human harassment in most places and many populations have declined worldwide. Consequently, they provide suitable substrate to better improve conservation education in schoolchildren. Responses to a questionnaire administered to 2,570 schoolchildren (7-14 years old) from 10 countries showed that many children liked snakes and that most of the students wanted to see snakes protected. Such counterintuitive results were supported by the explanations given by the children, notably the reasons they liked or disliked snakes. Previous physical contact with snakes was often associated with snake likeability. We also found strong and expected differences between countries: for instance, where venomous snakes represented a health risk, most children declared to be afraid of snakes. Overall, our results negate the simplistic, and previously unverified, adult view that snakes are necessarily perceived as frightening animals, thereby justifying their persecution. This study provides an encouraging message, suggesting that it is not compulsory to focus on charismatic animals to convince children to protect wildlife.
Organisms that produce more than one newborn at every reproductive event must choose between two ... more Organisms that produce more than one newborn at every reproductive event must choose between two options with respect to their reproductive output: to produce a few large or many small young. The decision will be influenced by the spectrum of prey sizes available to young. The ladder snake (Rhinechis scalaris), a heavy-bodied Mediterranean colubrid, is well suited for the study
Cientos de miles de reptiles y anfibios mueren en los aljibes de uso ganadero, según un equipo in... more Cientos de miles de reptiles y anfibios mueren en los aljibes de uso ganadero, según un equipo internacional que ha trabajado en el suroeste de Marruecos. En más de ochocientos aljibes visitados, las especies que quedan atrapadas superan la treintena, algunas amenazadas. El siguiente paso será proponer medidas correctoras.
In many vertebrates, foraging mode (active versus sit-and-wait) is tied to some traits of their n... more In many vertebrates, foraging mode (active versus sit-and-wait) is tied to some traits of their natural history such as morphology, type of prey, rate of food acquisition, and survival rate. We explore the correlates between some morphological traits of a Mediterranean colubrid and its feeding ecology and the predation risk, by comparing data on teeth number, tail damage, and diet.
Questionnaires are important tools for assessing attitudes regarding conservation issues. However... more Questionnaires are important tools for assessing attitudes regarding conservation issues. However, they are not easily comparable and their reliability has been insufficiently assessed. We examined factors influencing responses to open-and closed-ended questions about animal conservation to more than 600 schoolchildren (9 years old on average). We analysed the level of understanding, controllable (e.g. sample size) and less controllable factors (e.g. affectivity). Most children responded appropriately to the questions, but subtle changes in the phrasing influenced the answers. Affectivity towards endearing species and spontaneity also influenced the responses whereas small sample sizes ( 50 children) provided relatively stable patterns. Overall, we suggest that standardization of questionnaires administered over large spatial and time scales is needed to accurately assess children's attitudes towards conservation issues.
Predator-prey interactions are key factors in the evolution of defensive tactics. In snakes, shy ... more Predator-prey interactions are key factors in the evolution of defensive tactics. In snakes, shy organisms from which direct evidence of predator-prey interactions is difficult to obtain, injuries are potential indicators of both the nature and frequency of interactions. We studied the incidence of tail breakage and body scarring in the ladder snake, Rhinechis scalaris, an actively foraging Mediterranean snake, and tested several hypotheses that link body injuries and snake life-history traits, mainly under sexual and ontogenetic aspects. Evidence is presented supporting an ontogenetic shift in the frequency of tail breakage, with the incidence of tail loss increasing as a logistic function of snake size. We relate this finding to the adaptive significance of ontogenetic shifts in dorsal pattern and the reaction of snakes to approaching predators; small individuals are more likely to remain immobile than are medium to large individuals, the former aided by a concealing dorsal pattern with transverse lines, and the latter by a striped pattern. This species exhibited sex differences in body scarring but not in tail breakage, nor did we encounter evidence to suggest that snakes experience multiple tail breaks over time, thus failing to support the sexual difference and multiple tail breakage hypotheses. Moreover, we failed to find a lower frequency of body scarring than tail breakage; hence, our results do not afford evidence that frequency of tail breakage represents an inefficiency of predators in catching or dispatching ophidian prey.
Reproductive characteristics of the Viperine Snake, Natrix maura (Linnaeus, 1758), in the De- pre... more Reproductive characteristics of the Viperine Snake, Natrix maura (Linnaeus, 1758), in the De- presión de Granada (Southeastern Spain).- We studied 267 specimens of the Viperine snake, Natrix maura, from the Depresión of Granada (southeastern Iberian Peninsula) in order to determine size at sexual maturity, reproductive cycle, and fat body cycle in both sexes, as well as clutch size and laying
Zoologischer Anzeiger - A Journal of Comparative Zoology, 2013
Tail breakage can help reptiles to escape from predators. Despite the immediate advantage for sur... more Tail breakage can help reptiles to escape from predators. Despite the immediate advantage for survival, tail loss can also entail negative consequences. We have examined some potential costs associated to tail breakage in the colubrid snake Rhinechis scalaris (Schinz, 1822), a medium-sized terrestrial species with a high incidence of tail breakage (40.7% in the largest individuals). Tail damaged individuals were not smaller than undamaged individuals, fat-body levels (a measure of body condition) did not differ between tail damaged and tail undamaged individuals, and no relationship was found between the remaining pairs of subcaudal scales (a measure of tail-loss severity) and fatbody level in specimens with damaged tails. All results failed to support a cost in terms of overall body condition associated with tail breakage. The tail is of low importance for locomotion, there are no vital morphological structures in the tail necessary for a healthy physiology, and snakes undergo non regenerative tail loss.
Arid regions are increasingly being anthropogenically altered. In the north-western Sahara, a gro... more Arid regions are increasingly being anthropogenically altered. In the north-western Sahara, a growing road network facilitates the use of habitats adjacent to roads. In regions where livestock is the traditional and main economic resource, local people are currently building numerous water cisterns for watering livestock, leading to an increase in the extent of pasturing of domestic livestock. Cisterns may attract desert vertebrates and act as death traps for species with already sparse populations in these arid areas. This paper is the first to examine the impact of cisterns as lethal traps for amphibians and reptiles in the Sahara, using a survey of 823 cisterns in south-western Morocco to identify and quantify species affected. Four amphibians and 35 reptiles were trapped in cisterns, some of which were listed as threatened. At least 459 017 individual amphibians and reptiles were trapped annually within the study area. The low productivity and low population densities of terrestrial vertebrates in this arid region suggest cisterns have a substantial impact upon amphibian and reptile species. As cistern construction is increasing, management actions are required to mitigate this impact on the herpetological community.
Two spermatogenetic cycles, vernal and aestival, have been described in temperate colubrid snakes... more Two spermatogenetic cycles, vernal and aestival, have been described in temperate colubrid snakes. In both cycles, mating occurs in the spring, although vernal species produce spermatozoa in spring, just before mating, while aestival species use spermatozoa produced the previous summer. In this study, we describe the reproductive cycles of male and female Malpolon monspessulanus (Colubridae), and compare them to previously published cycles of five other snake species, four vernal and one aestival, inhabiting the same area. We also examine the consequences of both spermatogenesis cycles over the entire reproductive processes of male and female snakes in the south-eastern Iberian Peninsula. Vernal species mate later than do aestival species, as males must produce spermatozoa just prior to mating. However, vernal species are able to condense spermatogenesis and vitellogenesis processes, hence undertaking oviposition at the same time as aestival species. Here we discuss advantages of accomplishing the entire reproductive cycle in one (vernal species) or two (aestival species) calendar years. We also found that mature male M. monspessulanus exhibit decreased testes volume relative to body size. Large testes are expected in scenarios of sperm competition. The mating system of M. monspessulanus (territoriality, mate guarding, male-male combat) does not suggest sperm competition, hence it may be more advantageous for males of this species to invest in body size than in testes size.
It is difficult to measure predation risk for secretive animals such as snakes. The frequency of ... more It is difficult to measure predation risk for secretive animals such as snakes. The frequency of tail breakage has been suggested as a parameter for measuring predation risk in these reptiles. Consequently, we hypothesise that tail breakage frequency is expected to vary intraspecifically between populations submitted to different numbers of predators, probably, to different predation risk. The colubrid snake Natrix maura has adapted to living on fish farms, which are protected from aerial predators by wire mesh, so that these farms provide researchers with a predator-exclusion scenario. We measured tail breakage frequency in this snake on a fish farm and compared the results with data from three populations in natural settings in the Iberian Peninsula under assumed higher predation risk from a complete community of predators. A logistic regression analysis demonstrated that snake body size and predator exclusion affected the probability of tail breakage, while sex had no effect. We found an ontogenetic increase in the frequency of tail breakage, a general pattern in snakes and, notably, marked differences between populations according to predation risk: snakes from the fish farm showed a low frequency of tail breakage (5.1%), whereas snakes from natural habitats, with five-fold more potential predators on average, demonstrated a higher frequency of tail breakage (18.7%). We conclude that tail breakage frequency is a reliable indicator of predation risk in this aquatic snake.
The viperine snake Natrix maura is a common water snake, which forages on aquatic prey such as fi... more The viperine snake Natrix maura is a common water snake, which forages on aquatic prey such as fish and frogs in Western Mediterranean water bodies. Female viperine snakes collected from three populations at the Iberian Peninsula during the vitellogenesis period were compared. Mean clutch size and range, as well as the slope of the regression between body size and clutch size, did not show differences between populations. In contrast, mean size of enlarged follicles of females collected in May from the Ebro Delta proved significantly smaller than those of females from the Matarranya River (50 km far) and the Granada Depression (500 km far). There were no differences in climatic conditions between areas. However, seasonal variation in food availability was significantly different in the Ebro Delta. In this area, the rice fields are dry in early spring as men control the water flow, and prey are not available. This energetic constraint induced female viperine snakes to adjust reproductive timing according to seasonal availability and to delay vitellogenesis for at least one month. By contrast, other Mediterranean populations exhibited a rather high prey availability from early spring (e.g. Matarranya River), females being in good condition in this season and consequently vitellogenesis starting earlier than in the Ebro Delta. This study illustrates a new case of reproductive plasticity in snakes.
For cultural reasons and due to the narrow vision of environmental policy makers, most conservati... more For cultural reasons and due to the narrow vision of environmental policy makers, most conservation efforts focus on a few charismatic species and consequently neglect the majority of others under threat; many unpopular species are even killed in large numbers with little concern. Redressing this bias through educational programs is therefore important. Snakes are unpopular animals; they suffer from human harassment in most places and many populations have declined worldwide. Consequently, they provide suitable substrate to better improve conservation education in schoolchildren. Responses to a questionnaire administered to 2,570 schoolchildren (7-14 years old) from 10 countries showed that many children liked snakes and that most of the students wanted to see snakes protected. Such counterintuitive results were supported by the explanations given by the children, notably the reasons they liked or disliked snakes. Previous physical contact with snakes was often associated with snake likeability. We also found strong and expected differences between countries: for instance, where venomous snakes represented a health risk, most children declared to be afraid of snakes. Overall, our results negate the simplistic, and previously unverified, adult view that snakes are necessarily perceived as frightening animals, thereby justifying their persecution. This study provides an encouraging message, suggesting that it is not compulsory to focus on charismatic animals to convince children to protect wildlife.
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Papers by Mónica Feriche