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... 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.
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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... 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.
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.
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thermal ecology of Hermanns tortoise Testudo hermanni in summer and autumn
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... 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... 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. ...
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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... 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.
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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... 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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Reptiles live in a range of different habitats from tropical forests to temperate zones where the climate may change on seasonal or a daily basis. The thermal environment is a major determinant of how efficiently they can achieve optimum... more
Reptiles live in a range of different habitats from tropical forests to temperate zones where the climate may change on seasonal or a daily basis. The thermal environment is a major determinant of how efficiently they can achieve optimum or preferred body temperatures and, in terms of physiologically optimum body temperatures, these may not be possible in a natural environment. In this paper, null models have been employed to evaluate thermoregulatory efficiency in Hermann’s tortoise, Testudo hermanni, in high summer in central Montenegro when temperatures change on a daily basis. The study area is defined as a low-cost thermal environment and thus we assumed that tortoises should be able to achieve an efficient level of thermoregulation. However, the results varied and depended on where the tortoises operated and the weather conditions. High levels of efficiency were found during sunny weather in areas with abundant patches of shade and sunlit areas. These reflected the temperature...
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Reptiles live in a range of different habitats from tropical forests to temperate zones where the climate may change on seasonal or a daily basis. The thermal environment is a major determinant of how efficiently they can achieve optimum... more
Reptiles live in a range of different habitats from tropical forests to temperate zones where the climate may change on seasonal or a daily basis. The thermal environment is a major determinant of how efficiently they can achieve optimum or preferred body temperatures and, in terms of physiologically optimum body temperatures, these may not be possible in a natural environment. In this paper, null models have been employed to evaluate thermoregulatory efficiency in Hermann’s tortoise, Testudo hermanni, in high summer in central Montenegro when temperatures change on a daily basis. The study area is defined as a low-cost thermal environment and thus we assumed that tortoises should be able to achieve an efficient level of thermoregulation. However, the results
varied and depended on where the tortoises operated and the weather conditions. High levels of efficiency were found during sunny weather in areas with abundant patches of shade and sunlit areas. These reflected the temperatures of models placed in these areas and in females during cooler cloudy weather when thermoregulatory effort increased. Model temperatures placed in partially shaded sunlit areas were in better agreement with tortoise body temperatures than models in other
areas. Tortoise body temperatures were in closer agreement with set point temperatures than any of the null models placed in either open sunny, shaded or partially shaded areas, indicating that tortoise
movement was non-random and due to active thermoregulation.
varied and depended on where the tortoises operated and the weather conditions. High levels of efficiency were found during sunny weather in areas with abundant patches of shade and sunlit areas. These reflected the temperatures of models placed in these areas and in females during cooler cloudy weather when thermoregulatory effort increased. Model temperatures placed in partially shaded sunlit areas were in better agreement with tortoise body temperatures than models in other
areas. Tortoise body temperatures were in closer agreement with set point temperatures than any of the null models placed in either open sunny, shaded or partially shaded areas, indicating that tortoise
movement was non-random and due to active thermoregulation.
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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... 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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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... 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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The agile frog Rana dalmatina is a common and frequently studied species in Europe including long-term studies of population change. Several have employed spawn clump counts to give estimates of annual presence of reproductive females.... more
The agile frog Rana dalmatina is a common and frequently studied species in Europe including long-term studies of population change. Several have employed spawn clump counts to give estimates of annual presence of reproductive females. Spawn clumps are also subject to predation but little is known of the extent of losses but it could impact population densities significantly. The objective of the present study was to assess the extent of spawn clump losses due to predation in a population of R. dalmatina in western France using data from numbers of spawn clumps recorded over a four-year period (2019–2022). Spawn counts were greatest during 2019 but numbers declined with a zero count in 2022. Predation was greatest in 2021, the year total counts were lowest, but there were no statistical difference between annual losses, which varied from 22.9–41.6 %. Most spawn was deposited in a series of ditches rather than in the two available ponds but statistically predation
levels were in agreement, with ditches ranging from 26.1–40 % versus ponds 28.6–40 %. Observed predators were ducks and alien crayfish Procambarus clarkii. The latter consumes all stages of frog development and hence likely represents the greater threat, especially since it has the capacity for population increase to very high numbers.
levels were in agreement, with ditches ranging from 26.1–40 % versus ponds 28.6–40 %. Observed predators were ducks and alien crayfish Procambarus clarkii. The latter consumes all stages of frog development and hence likely represents the greater threat, especially since it has the capacity for population increase to very high numbers.
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The influence of temperature on the physiological processes in reptiles is well known, for example growth, reproduction and muscular energy are all temperature dependent. However, there may be constraints on the ability of a reptile to... more
The influence of temperature on the physiological processes in reptiles is well known, for example growth, reproduction and muscular energy are all temperature dependent. However, there may be constraints on the ability of a reptile to harness thermal energy, particularly during cold seasons in the temperate zones. Substrate selection is a key factor in enhancing thermoregulation since it can enhance rate of heat uptake. For example, wood substrates are known to increase rates of heat gain in basking reptiles enabling earlier attainment of optimum body temperatures
compared to other substrate types, which enables increased time available for other activities. In this paper we describe substrate use for basking in populations of Lacerta bilineata and Podarcis muralis in a hedgerow and a population of Podarcis muralis in a suburban garden in western France. The proportions of substrate used were compared against a null model of substrate availability. When different substrates were pooled based on material similarities both species were recorded in greater frequency on wood based materials in comparison to their availability compared to non-wood substrates. However at a finer level, in comparison to the null model of substrate availability (fallen tree branches, tree stumps, open ground etc), P. muralis showed strong substrate selection whereas L. bilineata did not depart significantly from the null model. We speculate that intra-specific aggression in L. bilineata was one possible cause of this result due to dominant individuals limiting access to prime basking sites in smaller or female lizards. Differences in communal basking between the two species supported this notion.
compared to other substrate types, which enables increased time available for other activities. In this paper we describe substrate use for basking in populations of Lacerta bilineata and Podarcis muralis in a hedgerow and a population of Podarcis muralis in a suburban garden in western France. The proportions of substrate used were compared against a null model of substrate availability. When different substrates were pooled based on material similarities both species were recorded in greater frequency on wood based materials in comparison to their availability compared to non-wood substrates. However at a finer level, in comparison to the null model of substrate availability (fallen tree branches, tree stumps, open ground etc), P. muralis showed strong substrate selection whereas L. bilineata did not depart significantly from the null model. We speculate that intra-specific aggression in L. bilineata was one possible cause of this result due to dominant individuals limiting access to prime basking sites in smaller or female lizards. Differences in communal basking between the two species supported this notion.
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Hermann's tortoise (Testudo hermanni Gmelin) of the Island of Asinara (NW Sardinia, Italy) has been studied during a period of four seasons. This population consisted of several individuals of large body size, some of them being... more
Hermann's tortoise (Testudo hermanni Gmelin) of the Island of Asinara (NW Sardinia, Italy) has been studied during a period of four seasons. This population consisted of several individuals of large body size, some of them being amongst the largest known for this species. Bony shells of males were commonly found on this island, while the same was not true for female bony shells. Although wild boars (Sus scrofa) are potential large sized predators for tortoises, the analysis of carapace morphology did not reveal injuries signs due to bites. Male tortoises could die due to up-turning, as the result of male-male combats during the mating season, to possible hyperthermia when upturned, and to predation carried out by birds particularly when upturned. Estimated density was 4.88 individuals ha-1, which was similar to that of conspecifics from other areas studied so far.
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Habitat fragmentation is widely recognized as a contributor to the decline of biodiversity, with amphibians one of the key groups impacted. To understand the effects of habitat fragmentation on amphibian populations requires long-term... more
Habitat fragmentation is widely recognized as a contributor to the decline of biodiversity, with amphibians one of the key groups impacted. To understand the effects of habitat fragmentation on amphibian populations requires long-term data sets showing population trends. In this paper, road mortalities were employed as proxies to describe long-term numbers of four populations of the spiny toad Bufo spinosus in western France during a 17-year period. Road mortalities were found during all months in all populations but were most frequent during October, November and December, the main migratory period. Large females were found significantly more frequently during these migration months, forming 45% of the total sample, compared with their presence from January to September (34.4%). The long-term trends were evaluated using regression analysis of the logarithmic (loge) transforms of annual counts as dependent variables against year as the independent variables. All coefficients showed ...
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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... 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.
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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... more
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...
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Most species of lizard are either diurnal or nocturnal, and it is extremely rare to find species that operate both diurnally and nocturnally, or that may shift from diurnality to partial nocturnality when conditions allow. However, niche... more
Most species of lizard are either diurnal or nocturnal, and it is extremely rare to find species that operate both diurnally and nocturnally, or that may shift from diurnality to partial nocturnality when conditions allow. However, niche expansion from diurnal to nocturnal habits (often referred to as the night-light niche) has rarely been reported in lizards (mainly in Anoles), and mostly through anecdotal reports. In West Africa, the rainbow lizard Agama agama is a conspicuous species across the region but also lives in suburban areas of towns and villages. It is a diurnal sun-basker operating at relatively high body temperatures of 36 °C and higher. In this paper, we describe a night-light niche expansion, i.e. nocturnal foraging and thermoregulation, in a small number of A. agama populations living in suburban areas. These lizards utilised radiant heat from incandescent light bulbs situated on the walls of buildings to mostly achieve target body temperatures and forage for and fed on five different groups of invertebrates. Foraging lizards had significantly higher body temperatures than inactive lizards. However, variance in body temperature was significantly greater in foraging lizards than in inactive lizards probably due to the necessity to shuttle between the incandescent night lights and cooler foraging areas during activity, a known cost of thermoregulation. Regression analysis of body temperatures against time of night in foraging lizards supported the notion that the lizards were maintaining body temperatures by actively thermoregulating whilst in inactive non-basking resting lizards during the same time period body temperatures declined. Although our results indicate a potential thermoregulatory benefit from using the night-light shift, we cannot be certain that this benefit is the direct cause of the shift, rather than an additional advantage when foraging.
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thermal ecology of Hermanns tortoise Testudo hermanni in summer and autumn
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Observations were made on the behaviour and body temperatures of the legless lizard Anguis fragilis when active above ground in outdoor enclosures. The lizards were most frequently observed in partially shaded locations followed by fully... more
Observations were made on the behaviour and body temperatures of the legless lizard Anguis fragilis when active above ground in outdoor enclosures. The lizards were most frequently observed in partially shaded locations followed by fully shaded areas; full basking and locomotory movement were minor activities irrespective of weather conditions. Weather conditions had no significant influence on behaviour. Tests for thermoregulation using null models indicated that the main reason for movement above ground was thermoregulatory. Body temperatures were significantly higher than shade operative temperatures but lower than operative temperatures in open locations whatever the weather. Standard deviations in body temperature, employed as a measure of thermoregulatory precision, were lower than standard deviations of operative temperatures in sunny weather but not significantly different from operative temperatures during overcast weather or shaded operative temperatures during sunny weath...
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Most species of lizard are either diurnal or nocturnal, and it is extremely rare to find species that operate both diurnally and nocturnally, or that may shift from diurnality to partial nocturnality when conditions allow. However, niche... more
Most species of lizard are either diurnal or nocturnal, and it is extremely rare to find species that operate both diurnally and nocturnally, or that may shift from diurnality to partial nocturnality when conditions allow. However, niche expansion from diurnal to nocturnal habits (often referred to as the night-light niche) has rarely been reported in lizards (mainly in Anoles), and mostly through anecdotal reports. In West Africa, the rainbow lizard Agama agama is a conspicuous species across the region but also lives in suburban areas of towns and villages. It is a diurnal sun-basker operating at relatively high body temperatures of 36 °C and higher. In this paper, we describe a night-light niche expansion, i.e. nocturnal foraging and thermoregulation, in a small number of A. agama populations living in suburban areas. These lizards utilised radiant heat from incandescent light bulbs situated on the walls of buildings to mostly achieve target body temperatures and forage for and fed on five different groups of invertebrates. Foraging lizards had significantly higher body temperatures than inactive lizards. However, variance in body temperature was significantly greater in foraging lizards than in inactive lizards probably due to the necessity to shuttle between the incandescent night lights and cooler foraging areas during activity, a known cost of thermoregulation. Regression analysis of body temperatures against time of night in foraging lizards supported the notion that the lizards were maintaining body temperatures by actively thermoregulating whilst in inactive non-basking resting lizards during the same time period body temperatures declined. Although our results indicate a potential thermoregulatory benefit from using the night-light shift, we cannot be certain that this benefit is the direct cause of the shift, rather than an additional advantage when foraging.