An automated temperature-based option for estimating surface activity and refuge use patterns in free-ranging animals

Davis, Jon R.; Taylor, Emily N.; DeNardo, Dale F.

doi:10.1016/j.jaridenv.2008.02.018

Cited by 21 publications

(16 citation statements)

References 35 publications

(59 reference statements)

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“…surface vs. retreat site) of individual reptiles based on body temperature and operative environmental temperatures (e.g. Christian & Weavers, ; Davis, Taylor, & DeNardo, ; Kerr et al., ), there have been no studies of the thermal biology of a lizard species during periods of inactivity (not hibernating) within a subterranean refuge site. We have demonstrated how two widely used thermal ecology methods (the measurement of operative and field body temperatures), can be combined to make inferences on activity budget of a burrowing species, which are inherently difficult to observe.…”

Section: Discussionmentioning

confidence: 99%

Under the weather?—The direct effects of climate warming on a threatened desert lizard are mediated by their activity phase and burrow system

Moore

Stow

Kearney

2018

Journal of Animal Ecology

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For ectotherms such as lizards, the importance of behavioural thermoregulation in avoiding thermal extremes is well-established and is increasingly acknowledged in modern studies of climate warming and its impacts. Less appreciated and understood are the buffering roles of retreat sites and activity phase, in part because of logistical challenges of studying below-ground activity. Burrowing and nocturnal activity are key behavioural adaptations that have enabled a diverse range of reptiles to survive extreme environmental temperatures within hot desert regions. Yet, the direct impact of recent global warming on activity potential has been hypothesised to have caused extinctions in desert lizards, including the Australian arid zone skink Liopholis kintorei. We test the relevance of this hypothesis through a detailed characterisation of the above- and below-ground thermal and hydric microclimates available to, and used by, L. kintorei. We integrate operative temperatures with observed body temperatures to construct daily activity budgets, including the inference of subterranean behaviour. We then assess the likelihood that contemporary and future local extinctions in this species, and those of similar burrowing habits, could be explained by the direct effects of warming on its activity budget and exposure to thermal extremes. We found that L. kintorei spent only 4% of its time active on the surface, primarily at dusk, and that overall potential surface activity will be increased, not restricted, with climate warming. The burrow system provides an exceptional buffer to current and future maximum extremes of temperature (≈40°C reduction from potential surface temperatures), and desiccation (burrows near 100% humidity). Therefore, any climate warming impacts on this species are likely to be indirect. Our findings reflect the general buffering capacity of underground microclimates, therefore, our conclusions for L. kintorei are more generally applicable to nocturnal and crepuscular ectotherms, and highlight the need to consider the buffering properties of retreat sites and activity phase when forecasting climate change impacts.

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Section: Discussionmentioning

confidence: 99%

Under the weather?—The direct effects of climate warming on a threatened desert lizard are mediated by their activity phase and burrow system

Moore

Stow

Kearney

2018

Journal of Animal Ecology

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“…Two separate studies report rattlesnakes to be surface active approximately 50% of the time (Beck, 1995;Davis et al, 2008). Considering we did not track these snakes year-round, our estimate of 80% would most likely diminish if snakes were tracked during winter months when snakes are less active.…”

Section: Discussionmentioning

confidence: 99%

No drought about it: Effects of supplemental hydration on the ecology, behavior, and physiology of free-ranging rattlesnakes

Capehart

Escallón

Vernasco

et al. 2016

Journal of Arid Environments

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Hydration is a critical element for many physiological processes in vertebrates. While it seems intuitive that drought is stressful to animals, studies examining drought are typically observational and do not explicitly assess how the hydration state of study subjects influences their physiology and behavior. We examined how hydration affects several physiological and behavioral variables in free-ranging Northern Pacific rattlesnakes (Crotalus oreganus oreganus) by experimentally manipulating their hydration levels in the field. Our results suggest that supplemental water has a significant effect on reproduction, as all hydrated females gave birth during the experiment, while no control females did. We saw no effect of hydration on movement parameters; males moved a larger total distance and had larger home ranges than females, regardless of hydration status. Interestingly, body condition at the end of the study was significantly higher in hydrated snakes, suggesting that hydrated individuals might have been acquiring more food than control snakes. We saw no effect on baseline stress hormone concentrations or their increase in response to an acute stressor. Additional experimental studies are needed to better understand the pivotal roles of hydration in the physiology and behavior of reptiles.

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“…), where T b of translocated snakes takes a midday dive and remains low until the following morning, supports this “extended hiding” hypothesis. Future studies could employ automated temperature‐based activity estimation (TBAE) to empirically test this hypothesis (Davis et al, ). This technique allows for the estimation of activity times and patterns in free‐ranging organisms, via the synchronization of T air and T b temporally plotted together on the same graph.…”

Section: Discussionmentioning

confidence: 99%

Evaluating the thermal effects of translocation in a large‐bodied pitviper

2014

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Acute stressors can be costly, often requiring alteration of normal physiological processes to mitigate their effects. Animal translocation may be a very stressful event and result in a reduced ability to maintain homeostasis. The impacts of translocation on the thermal ecology of ectothermic vertebrates, which may rely on preferred habitats for thermoregulation, are currently unknown. In this study, 22 adult male Northern Pacific rattlesnakes (Crotalus oreganus oreganus) were implanted with automated temperature loggers and radio-tracked. Snakes were assigned to one of three treatments: translocation, handling control, and undisturbed control. Short-distance translocation (SDT) and handling treatments were applied weekly for 6 weeks. Hourly body temperature (Tb ) was recorded during the course of the study. Mean Tb was impacted in a time-dependent fashion, where translocated snakes had lower mean Tb than handled controls during the first week of the study only, especially the first 24 hr after translocation. Separating the dataset into day and night revealed that this effect was localized to Tb variation during the day only. Variance in temperature was not impacted by translocation or handling. Snake body mass and time of year were the major factors influencing the thermal profiles of these rattlesnakes. Thermal ecology in male rattlesnakes is resilient to SDT, suggesting that they quickly resume normal behaviors following repeated bouts of acute capture stress and disturbance of their spatial ecology. This study provides support for SDT as a safe measure for mitigating human-snake interactions and facilitating conservation practices regarding male snakes, which are the most frequently encountered sex.

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An automated temperature-based option for estimating surface activity and refuge use patterns in free-ranging animals

Cited by 21 publications

References 35 publications

Under the weather?—The direct effects of climate warming on a threatened desert lizard are mediated by their activity phase and burrow system

Under the weather?—The direct effects of climate warming on a threatened desert lizard are mediated by their activity phase and burrow system

No drought about it: Effects of supplemental hydration on the ecology, behavior, and physiology of free-ranging rattlesnakes

Evaluating the thermal effects of translocation in a large‐bodied pitviper

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