Fine-Scale Tracking of Ambient Temperature and Movement Reveals Shuttling Behavior of Elephants to Water

Movement strategies of animals have been well studied as a function of ecological drivers (e.g., forage selection and avoiding predation) rather than physiological requirements (e.g., thermoregulation). Thermal stress is a major concern for large mammals, especially for savanna elephants (Loxodonta africana), which have amongst the greatest challenge for heat dissipation in hot and arid environments. Therefore, elephants must make decisions about where and how fast to move to reduce thermal stress. We tracked 14 herds of elephant in Kruger National Park (KNP), South Africa, for 2 years, using GPS collars with inbuilt temperature sensors to examine the influence of temperature on movement strategies, particularly when accessing water. We first confirmed that collar-mounted temperature loggers captured hourly variation in relative ambient temperatures across the landscape, and, thus, could be used to predict elephant movement strategies at fine spatio-temporal scales. We found that elephants moved slower in more densely wooded areas, but, unexpectedly, moved faster at higher temperatures, especially in the wet season compared to the dry season. Notably, this speed of movement was highest when elephants were approaching and leaving water sources. Visits to water showed a periodic shuttling pattern, with a peak return rate of 10–30 h, wherein elephants were closest to water during the hotter times of the day, and spent longer at water sources in the dry season compared to the wet season. When elephants left water, they showed low fidelity to the same water source, and traveled farther in the dry season than in the wet season. In KNP, where water is easily accessible, and the risk of poaching is low, we found that elephants use short, high-speed bursts of movement to get to water at hotter times of day. This strategy not only provides the benefit of predation risk avoidance, but also allows them to use water to thermoregulate. We demonstrate that ambient temperature is an important predictor of movement and water use across the landscape, with elephants responding facultatively to a “landscape of thermal stress.

Details matter when modelling the effects of animal personality on the spatial distribution of foragers

By means of a simulation study, DiNuzzo & Griffen [1] investigate whether individual variation in a personality trait can explain ‘undermatching’, an often-observed deviation from the ideal free distribution (IFD). Here, we raise five points of concern about this study, regarding (i) the interpretation of the results in terms of personality variation; (ii) deficiencies in the technical implementation of the model, leading to wrong conclusions; (iii) the effects of population size on deviations from the IFD; (iv) the measure used for quantifying deviations from the IFD and (v) the analysis of the mud crab data. Finally, we provide an overview of the evolutionary ramifications of the relation between animal personality and the IFD

Novel pathogen introduction rapidly alters the evolution of movement, restructuring animal societies

Animal social interactions are the outcomes of evolved strategies that integrate the costs and benefits of being sociable. Using a novel mechanistic, evolutionary, individual-based simulation model, we examine how animals balance the risk of pathogen transmission against the benefits of social information about resource patches, and how this determines the emergent structure of spatial social networks. We study a scenario in which a fitness-reducing infectious pathogen is introduced into a population which has initially evolved movement rules in its absence. Pathogen introduction leads to a rapid evolutionary shift, within only a few generations, in animal social-movement strategies. Generally, animals adopt a dynamic social distancing behaviour, trading more movement away from individuals (and less intake) for lower infection risk, but there is considerable individual variation in these social movement strategies. Pathogen-adapted populations are more widely dispersed over the landscape, and thus have lessclustered social networks than their pre-introduction, pathogen-naive ancestors. Running simple epidemiological models on these emergent social networks, we show that diseases do indeed spread more slowly through pathogen-adapted animal societies. The post-introduction, pathogen-adapted movement strategy mix is stongly influenced by a combination of landscape productivity and diseasecost. Our model suggests how the introduction of an infectious pathogen to a population rapidly changes social structure. While such events might make populations more resilient to future disease outbreaks, this is at the cost of social information benefits. Overall, we offer both a general modelling framework and initial predictions for the evolutionary consequences of wildlife pathogen spillovers

The Joint Evolution of Animal Movement and Competition Strategies

Competition typically takes place in a spatial context, but eco-evolutionary models rarely address the joint evolution of movement and competition strategies. Here we investigate a spatially explicit forager-kleptoparasite model where consumers can either forage on a heterogeneous resource landscape or steal resource items from conspecifics (kleptoparasitism). We consider three scenarios: (1) foragers without kleptoparasites, (2) consumers specializing as foragers or as kleptoparasites, and (3) consumers that can switch between foraging and kleptoparasitism depending on local conditions. We model movement strategies as individual-specific combinations of preferences for environmental cues, similar to step-selection coefficients. Using mechanistic, individual-based simulations, we study the joint evolution of movement and competition strategies, and we investigate the implications for the distribution of consumers over this landscape. Movement and competition strategies evolve rapidly and consistently across scenarios, with marked differences among scenarios, leading to differences in resource exploitation patterns. In scenario 1, foragers evolve considerable individual variation in movement strategies, while in scenario 2, movement strategies show a swift divergence between foragers and kleptoparasites. In scenario 3, where individuals’ competition strategies are conditional on local cues, movement strategies facilitate kleptoparasitism, and individual consistency in competition strategy also emerges. Even in the absence of kleptoparasitism (scenario 1), the distribution of consumers deviates considerably from predictions of ideal free distribution models because of the intrinsic difficulty of moving effectively on a depleted resource landscape with few reliable cues. Our study emphasizes the advantages of a mechanistic approach when studying competition in a spatial context and suggests how evolutionary modeling can be integrated with current work in animal movement ecology

Family size dynamics in wintering geese

Many bird populations are made up of social units with differences in size and social status. Of these, the family and flock structure of geese Anserini are among the better known. However, how the association of juvenile geese with their parents in families influences the migration timing and space-use of populations, as well as the events leading to juvenile independence are not well understood. We focus on family size dynamics of the Greater White-fronted Goose Anser a. albifrons on its wintering grounds in the Netherlands and northern Germany, where we gathered 17 years of observation data on foraging flocks and tracked 13 complete families with GPS transmitters. We explored how social status and family size affected wintering site choice and migration timing as well as how and why family sizes decreased. We found that family size decreased strongly during autumn migration, likely from juvenile death due to insufficient fuelling. It further decreased through the winter, here seemingly by juveniles accidentally splitting off during strong disturbance events. Different from previous findings, a large proportion of juveniles became independent during winter. Large families generally arrived later to the wintering grounds, wintered further from the breeding grounds and departed later for spring migration than adults without young. Independent young left for spring migration last. Thus, White-fronted Geese are differential migrants by social status. In combination with the observation of low breeding success in this population in recent years, our findings improve the understanding of its spatial and temporal patterns during winter, and their apparent changes. This can support conservation and management decisions for both White-fronted Geese as well as other large migrants with complex age and social structure.</p

Gray squirrels consume anthropogenic food waste most often during winter

Urban habitats provide wildlife with predictable, easily accessible and abundant food sources in the form of human food waste. Urban eastern gray squirrels (Sciurus carolinensis) are commonly observed feeding in trash bins, but we lack data regarding the type, quantity and seasonal changes in food waste usage. We observed five trash bins on an urban university campus during four different observation periods. We recorded the time squirrels spent on and inside trash bins and type of retrieved food items. We also recorded ambient temperature, human presence and trash bin filling. Moreover, we determined changes in squirrel population density in a natural and three anthropogenic habitats during the same periods. Trash bins were fuller when human presence was higher. The higher human presence, the more squirrels went on and inside the bin, but there was no effect on number of retrieved food items. Trash bin usage by squirrels decreased when ambient temperature and bin filling increased. Most food items were retrieved during the coldest observation period, a period of high human presence, and the majority of retrieved food items were starchy foods (e.g., bread, French fries). The relationship between the number of squirrels observed along transects and a measure of urbanization, the normalized difference built-up index, was negative in periods with high ambient temperatures and positive in periods with low ambient temperatures, indicating winter may be less challenging in urban areas, likely facilitated by the availability of anthropogenic food sources, allowing a higher level of activity throughout winter

Fine-scale tracking of ambient temperature and movement reveals shuttling behavior of elephants to water

<p>Movement strategies of animals have been well studied as a function of ecological drivers (e.g., forage selection and avoiding predation) rather than physiological requirements (e.g., thermoregulation). Thermal stress is a major concern for large mammals, especially for savanna elephants (Loxodonta africana), which have amongst the greatest challenge for heat dissipation in hot and arid environments. Therefore, elephants must make decisions about where and how fast to move to reduce thermal stress. We tracked 14 herds of elephant in Kruger National Park (KNP), South Africa, for 2 years, using GPS collars with inbuilt temperature sensors to examine the influence of temperature on movement strategies, particularly when accessing water. We first confirmed that collar-mounted temperature loggers captured hourly variation in relative ambient temperatures across the landscape, and, thus, could be used to predict elephant movement strategies at fine spatio-temporal scales. We found that elephants moved slower in more densely wooded areas, but, unexpectedly, moved faster at higher temperatures, especially in the wet season compared to the dry season. Notably, this speed of movement was highest when elephants were approaching and leaving water sources. Visits to water showed a periodic shuttling pattern, with a peak return rate of 10-30 h, wherein elephants were closest to water during the hotter times of the day, and spent longer at water sources in the dry season compared to the wet season. When elephants left water, they showed low fidelity to the same water source, and traveled farther in the dry season than in the wet season. In KNP, where water is easily accessible, and the risk of poaching is low, we found that elephants use short, high-speed bursts of movement to get to water at hotter times of day. This strategy not only provides the benefit of predation risk avoidance, but also allows them to use water to thermoregulate. We demonstrate that ambient temperature is an important predictor of movement and water use across the landscape, with elephants responding facultatively to a "landscape of thermal stress."</p

Fine-Scale Tracking of Ambient Temperature and Movement Reveals Shuttling Behavior of Elephants to Water

Movement strategies of animals have been well studied as a function of ecological drivers (e.g., forage selection and avoiding predation) rather than physiological requirements (e.g., thermoregulation). Thermal stress is a major concern for large mammals, especially for savanna elephants (Loxodonta africana), which have amongst the greatest challenge for heat dissipation in hot and arid environments. Therefore, elephants must make decisions about where and how fast to move to reduce thermal stress. We tracked 14 herds of elephant in Kruger National Park (KNP), South Africa, for 2 years, using GPS collars with inbuilt temperature sensors to examine the influence of temperature on movement strategies, particularly when accessing water. We first confirmed that collar-mounted temperature loggers captured hourly variation in relative ambient temperatures across the landscape, and, thus, could be used to predict elephant movement strategies at fine spatio-temporal scales. We found that elephants moved slower in more densely wooded areas, but, unexpectedly, moved faster at higher temperatures, especially in the wet season compared to the dry season. Notably, this speed of movement was highest when elephants were approaching and leaving water sources. Visits to water showed a periodic shuttling pattern, with a peak return rate of 10-30 h, wherein elephants were closest to water during the hotter times of the day, and spent longer at water sources in the dry season compared to the wet season. When elephants left water, they showed low fidelity to the same water source, and traveled farther in the dry season than in the wet season. In KNP, where water is easily accessible, and the risk of poaching is low, we found that elephants use short, high-speed bursts of movement to get to water at hotter times of day. This strategy not only provides the benefit of predation risk avoidance, but also allows them to use water to thermoregulate. We demonstrate that ambient temperature is an important predictor of movement and water use across the landscape, with elephants responding facultatively to a ``landscape of thermal stress.'

Data from: Fine-scale tracking of ambient temperature and movement reveals shuttling behavior of elephants to water

Thaker M, Gupte PR, Prins HHT, Slotow R, Vanak AT (2019) Fine-scale tracking of ambient temperature and movement reveals shuttling behavior of elephants to water. Frontiers in Ecology and Evolution 7:4. doi:10.3389/fevo.2019.00004,Movement strategies of animals have been well studied as a function of ecological drivers (e.g., forage selection and avoiding predation) rather than physiological requirements (e.g., thermoregulation). Thermal stress is a major concern for large mammals, especially for savanna elephants (Loxodonta africana), which have amongst the greatest challenge for heat dissipation in hot and arid environments. Therefore, elephants must make decisions about where and how fast to move to reduce thermal stress. We tracked 14 herds of elephant in Kruger National Park (KNP), South Africa, for 2 years, using GPS collars with inbuilt temperature sensors to examine the influence of temperature on movement strategies, particularly when accessing water. We first confirmed that collar-mounted temperature loggers captured hourly variation in relative ambient temperatures across the landscape, and, thus, could be used to predict elephant movement strategies at fine spatio-temporal scales. We found that elephants moved slower in more densely wooded areas, but, unexpectedly, moved faster at higher temperatures, especially in the wet season compared to the dry season. Notably, this speed of movement was highest when elephants were approaching and leaving water sources. Visits to water showed a periodic shuttling pattern, with a peak return rate of 10–30 h, wherein elephants were closest to water during the hotter times of the day, and spent longer at water sources in the dry season compared to the wet season. When elephants left water, they showed low fidelity to the same water source, and traveled farther in the dry season than in the wet season. In KNP, where water is easily accessible, and the risk of poaching is low, we found that elephants use short, high-speed bursts of movement to get to water at hotter times of day. This strategy not only provides the benefit of predation risk avoidance, but also allows them to use water to thermoregulate. We demonstrate that ambient temperature is an important predictor of movement and water use across the landscape, with elephants responding facultatively to a “landscape of thermal stress.”