Urbanisation impacts on both abiotic and biotic characteristics of the environment and is likely ... more Urbanisation impacts on both abiotic and biotic characteristics of the environment and is likely to bring new selective pressures on animal species living within these areas. The common European wall lizard Podarcis muralis adapts well to urbanisation and indeed may be described as the archetypical urban lizard. In this paper we investigated some aspects of the demography of two populations of P. muralis from western France, one living in a hedgerow system situated in an agricultural area on the edge of a village and a second in an urban garden. The active year in both populations was from February-March until October-December, the latter in the urban garden where temperatures were higher. Numbers decreased from around June then increased again during September but this varied annually and between populations. Diversity and equality indexes for both populations were high, especially in females, indicating a range of individuals and their frequency of presence. Both populations were therefore stable despite only limited numbers of lizards being present for more than one year. Male lizards with high presence were more frequently seen in the company of females than males that were seen less frequently. Hatchling lizards were seen from June after the spring mating period with a second period of hatchlings appearing during autumn. This supports the notion that females annually deposit two clutches of eggs in the area.
The expansion of human activities across natural environments is now well known. This includes ag... more The expansion of human activities across natural environments is now well known. This includes agricultural activities that effectively render many former natural environments sterile habitats for animals. Very often, what remains of the natural habitat are hedgerows that serve as habitat or pathways for movement between habitats for many species, including reptiles. In this study, we describe population changes in the western green lizard, Lacerta bilineata, in a hedgerow system in western France. The results are derived from a univariate diversity analysis of photographic data to identify individual lizards over a 4-year study period. Lizards were sighted from March April to October early November but there was a midsummer gap in sightings during July–August. The annual presence of individual lizards was low, both between and within years, but based on the diversity analysis, the overall stability of the population was high. Female numbers varied and were highest in 2020, but juveniles were highest in 2023; the numbers of males present each year were approximately the same. Individual lizards that were present before the midsummer gap were mostly absent after the midsummer gap and were replaced by new individuals. Incidences of autotomy were low in males and juveniles and were not recorded in females. In general, the results suggest that the lizards move through hedgerow systems but remain in a specific section for reproduction from March to July. Through this study, we also highlight the importance of univariate diversity formulas to obtain robust results in investigations of the demographic aspects of animal populations that are easy to monitor.
... Thermoregulatory behaviour of reptiles in the field and in captivity. In Townson, S. and Lawr... more ... Thermoregulatory behaviour of reptiles in the field and in captivity. In Townson, S. and Lawrence, K. (Eds), Reptiles: Breeding, Behaviour and Veterinary Aspects. ... Homage to Santa Anita: thermal sensitivity of sprint speed in agamid lizards. Euolution 37:10751084. ...
Acta Oecologica-international Journal of Ecology, May 1, 2021
Abstract Reports of declining amphibians are a major concern for conservation given their role as... more Abstract Reports of declining amphibians are a major concern for conservation given their role as indicators of environmental change. This includes potentially impacting on the ecology other species and highlights the importance of monitoring long-term changes in amphibian populations. The core difficulty is gathering long term data sets that as well as being time consuming, may be costly and impractical for logistical reasons. Road mortalities have value in this respect since they are highly visible and have been frequently used as a metric to monitor changes in a variety of animal populations. In this paper they have been employed as proxies to estimate long-term population changes in four European species of amphibians. From January 2005 to December 2019 a total of 747 amphibian mortalities were recorded, the majority of which were urodeles. Most individuals were adults that entered roads during the annual migration period. Long term annual counts fluctuated widely in all species and peaked during the 4-year period from 2009 to 2012 with second period of high numbers in Triturus marmoratus and Hyla arborea during 2018 and 2019. Long-term population trends were evaluated using regression analysis of the logarithmic (loge) transforms of annual counts against year as independent variables, which were then tested against a hypothetical 0 regression coefficient, indicative of population stability. The results indicated long-term stability in T. marmoratus and H. arborea but potential declines in Lissotriton helveticus and Pelophylax lessonae, the latter showing metapopulation extinctions followed by recolonisation. Stepwise regression of potential climate drivers in amphibian numbers suggested a 2-year lag of rainfall during October and December were potential factors involved in population change.
The relationship between a reptile and its thermal environment is a key feature of habitat use, w... more The relationship between a reptile and its thermal environment is a key feature of habitat use, which may be impacted by, among others, the requirements for food, avoidance of competitors and predators. Juvenile lizards are subject to the same ecological pressures, but may additionally experience predation or exclusion from prime basking site by adults and hence their capacity to achieve preferred body temperatures. In this paper, we examined basking site selection in juvenile western green lizards, Lacerta bilineata and compared them to basking site availability. Secondly, measurements of morning substrate temperatures at different basking sites were compared to basking site selection over the same period. The results indicated that juveniles selected substrates with fast heating surfaces, for example fallen branches for basking, in greater frequency than their availability but in even greater than expected frequency on the cooler surfaces of clusters of bramble plant. This finding contrasted with basking site selection in adult L. bilineata in a previous study where wood surfaces was preferred over non-wood surfaces whilst avoiding basking on bramble. This illustrates the different ecological requirements between adults and juveniles.
Urbanisation impacts on both abiotic and biotic characteristics of the environment and is likely ... more Urbanisation impacts on both abiotic and biotic characteristics of the environment and is likely to bring new selective pressures on animal species living within these areas. The common European wall lizard Podarcis muralis adapts well to urbanisation and indeed may be described as the archetypical urban lizard. In this paper we investigated some aspects of the demography of two populations of P. muralis from western France, one living in a hedgerow system situated in an agricultural area on the edge of a village and a second in an urban garden. The active year in both populations was from February-March until October-December, the latter in the urban garden where temperatures were higher. Numbers decreased from around June then increased again during September but this varied annually and between populations. Diversity and equality indexes for both populations were high, especially in females, indicating a range of individuals and their frequency of presence. Both populations were therefore stable despite only limited numbers of lizards being present for more than one year. Male lizards with high presence were more frequently seen in the company of females than males that were seen less frequently. Hatchling lizards were seen from June after the spring mating period with a second period of hatchlings appearing during autumn. This supports the notion that females annually deposit two clutches of eggs in the area.
The expansion of human activities across natural environments is now well known. This includes ag... more The expansion of human activities across natural environments is now well known. This includes agricultural activities that effectively render many former natural environments sterile habitats for animals. Very often, what remains of the natural habitat are hedgerows that serve as habitat or pathways for movement between habitats for many species, including reptiles. In this study, we describe population changes in the western green lizard, Lacerta bilineata, in a hedgerow system in western France. The results are derived from a univariate diversity analysis of photographic data to identify individual lizards over a 4-year study period. Lizards were sighted from March April to October early November but there was a midsummer gap in sightings during July–August. The annual presence of individual lizards was low, both between and within years, but based on the diversity analysis, the overall stability of the population was high. Female numbers varied and were highest in 2020, but juveniles were highest in 2023; the numbers of males present each year were approximately the same. Individual lizards that were present before the midsummer gap were mostly absent after the midsummer gap and were replaced by new individuals. Incidences of autotomy were low in males and juveniles and were not recorded in females. In general, the results suggest that the lizards move through hedgerow systems but remain in a specific section for reproduction from March to July. Through this study, we also highlight the importance of univariate diversity formulas to obtain robust results in investigations of the demographic aspects of animal populations that are easy to monitor.
... Thermoregulatory behaviour of reptiles in the field and in captivity. In Townson, S. and Lawr... more ... Thermoregulatory behaviour of reptiles in the field and in captivity. In Townson, S. and Lawrence, K. (Eds), Reptiles: Breeding, Behaviour and Veterinary Aspects. ... Homage to Santa Anita: thermal sensitivity of sprint speed in agamid lizards. Euolution 37:10751084. ...
Acta Oecologica-international Journal of Ecology, May 1, 2021
Abstract Reports of declining amphibians are a major concern for conservation given their role as... more Abstract Reports of declining amphibians are a major concern for conservation given their role as indicators of environmental change. This includes potentially impacting on the ecology other species and highlights the importance of monitoring long-term changes in amphibian populations. The core difficulty is gathering long term data sets that as well as being time consuming, may be costly and impractical for logistical reasons. Road mortalities have value in this respect since they are highly visible and have been frequently used as a metric to monitor changes in a variety of animal populations. In this paper they have been employed as proxies to estimate long-term population changes in four European species of amphibians. From January 2005 to December 2019 a total of 747 amphibian mortalities were recorded, the majority of which were urodeles. Most individuals were adults that entered roads during the annual migration period. Long term annual counts fluctuated widely in all species and peaked during the 4-year period from 2009 to 2012 with second period of high numbers in Triturus marmoratus and Hyla arborea during 2018 and 2019. Long-term population trends were evaluated using regression analysis of the logarithmic (loge) transforms of annual counts against year as independent variables, which were then tested against a hypothetical 0 regression coefficient, indicative of population stability. The results indicated long-term stability in T. marmoratus and H. arborea but potential declines in Lissotriton helveticus and Pelophylax lessonae, the latter showing metapopulation extinctions followed by recolonisation. Stepwise regression of potential climate drivers in amphibian numbers suggested a 2-year lag of rainfall during October and December were potential factors involved in population change.
The relationship between a reptile and its thermal environment is a key feature of habitat use, w... more The relationship between a reptile and its thermal environment is a key feature of habitat use, which may be impacted by, among others, the requirements for food, avoidance of competitors and predators. Juvenile lizards are subject to the same ecological pressures, but may additionally experience predation or exclusion from prime basking site by adults and hence their capacity to achieve preferred body temperatures. In this paper, we examined basking site selection in juvenile western green lizards, Lacerta bilineata and compared them to basking site availability. Secondly, measurements of morning substrate temperatures at different basking sites were compared to basking site selection over the same period. The results indicated that juveniles selected substrates with fast heating surfaces, for example fallen branches for basking, in greater frequency than their availability but in even greater than expected frequency on the cooler surfaces of clusters of bramble plant. This finding contrasted with basking site selection in adult L. bilineata in a previous study where wood surfaces was preferred over non-wood surfaces whilst avoiding basking on bramble. This illustrates the different ecological requirements between adults and juveniles.
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data to identify individual lizards over a 4-year study period. Lizards were sighted from March April to October early November but there was a midsummer gap in sightings during July–August. The annual presence of individual lizards was low, both between and within years, but based on the diversity analysis, the overall stability of the population was high. Female numbers varied and were highest in 2020, but juveniles were highest in 2023; the numbers of males present each year were approximately the same. Individual lizards that were present before the midsummer gap were mostly absent after the midsummer gap and were replaced by new individuals. Incidences of autotomy were low in males and juveniles and were not recorded in females. In general, the results suggest that the lizards move through hedgerow systems but remain in a specific section for reproduction from March to July. Through this study, we also highlight the importance of univariate diversity formulas to obtain robust results in investigations of the demographic aspects of animal populations that are easy to monitor.
data to identify individual lizards over a 4-year study period. Lizards were sighted from March April to October early November but there was a midsummer gap in sightings during July–August. The annual presence of individual lizards was low, both between and within years, but based on the diversity analysis, the overall stability of the population was high. Female numbers varied and were highest in 2020, but juveniles were highest in 2023; the numbers of males present each year were approximately the same. Individual lizards that were present before the midsummer gap were mostly absent after the midsummer gap and were replaced by new individuals. Incidences of autotomy were low in males and juveniles and were not recorded in females. In general, the results suggest that the lizards move through hedgerow systems but remain in a specific section for reproduction from March to July. Through this study, we also highlight the importance of univariate diversity formulas to obtain robust results in investigations of the demographic aspects of animal populations that are easy to monitor.