Seasonal patterns in behavior and glucocorticoid secretion of a specialist Holarctic tree squirrel (Sciurus aberti)

Zhang, Victor; Buck, C. Loren

doi:10.1007/s00360-022-01429-6

Cited by 6 publications

(6 citation statements)

References 125 publications

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“…The indicators of acute stress, such as struggle rate and vocalization, appear to be less straightforward, as they are likely influenced by other factors that might not always be easy to interpret. For instance, it seems that the struggle rate was affected by environmental conditions (seasonal effects), and/or elevated glucocorticoids which have also been shown to influence behaviors [88]. Additionally, vocalization was probably intensified by the initial interaction with a human (handling), but its elevated level was only evident during the subsequent encounter.…”

Section: Discussionmentioning

confidence: 99%

Long-term, medium-term and acute stress response of urban populations of Eurasian red squirrels affected by different levels of human disturbance

Beliniak,

Gryz,

Klich

et al. 2024

PLoS ONE

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Animals in urban areas often encounter novel and potentially stressful conditions. It is important to understand how wildlife cope with anthropogenic disturbance. To investigate this specific adaptation we live-trapped squirrels in two study sites in Warsaw: a forest reserve and an urban park and we estimated stress responses at three levels: long-term and medium-term stress (the level of stress hormones, i.e. cortisol and cortisone concentrations, in hair and feces) and acute reaction to human-induced stress (measured during handling with the aid of the three indices: breath rate, struggle rate, and vocalization). According to GLMM models no difference in the stress hormones level was found between the two populations. The only differences in cortisol concentrations clearly depended on the season, i.e. being higher in autumn and winter comparying to other seasons. There was no influence of sex, or reproductive status on stress hormones. Forest squirrels had significantly higher breath rates, suggesting they were more stressed by handling. There was no difference in the struggle rate between study areas, this index was mostly affected by season (i.e. being highest in winter). First-trapped squirrels vocalized less than during the subsequent trappings. Assumingly, during the first, and more stressful trapping, squirrels used ‘freezing’ and/or little vocalization, while during next captures they used alarm calls to warn conspecifics. Overall, we showed that the two squirrel populations differed only in terms of their breath rate. This suggests that they did not differ in medium-term and long-term stress in general, but they can differ in acute response to handling. This also suggests that both populations were similarly affected by environmental factors. The lack of clear effects may also be due to population heterogeneity. Thus, in order to assess the effects of anthropogenic stressors a broader range of indicators and diverse analytical methods, including behavioral analyses, should be employed.

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Section: Discussionmentioning

confidence: 99%

Long-term, medium-term and acute stress response of urban populations of Eurasian red squirrels affected by different levels of human disturbance

Beliniak,

Gryz,

Klich

et al. 2024

PLoS ONE

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Section: Discussionmentioning

confidence: 99%

“…However, only few studies investigated seasonal fluctuations in behavior in free‐living Sciurids (Arctic ground squirrels, Urocitellus parryii : Chmura et al. 2020; Abert's squirrels, Sciurus aberti : Zhang & Buck 2022). In our studied species, the seasonal variation in trait expression could be linked to tree phenology; new fresh cones with mature seeds are available from the end of summer and during autumn and winter (Romeo et al.…”

Section: Discussionmentioning

confidence: 99%

“…Animals may show some degree of behavioral plasticity among seasons to cope with predictable abiotic and biotic environmental conditions (e.g. changes in photoperiod, rainfall, temperature, tree-seed availability), especially at high latitudes and altitudes (Zhang & Buck 2022; see also Beaman et al 2016). However, only few studies investigated seasonal fluctuations in behavior in free-living Sciurids (Arctic ground squirrels, Urocitellus parryii: Chmura et al 2020; Abert's squirrels, Sciurus aberti: Zhang & Buck 2022).…”

Section: Other Factors Affecting the Expression Of Personality Traitsmentioning

confidence: 99%

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Living on the edge: morphological and behavioral adaptations to a marginal high‐elevation habitat in an arboreal mammal

et al. 2022

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Habitats are characterized by different local environmental conditions that influence both behavior and morphology of species, which can result in habitat-dependent phenotypic differences among animals living in heterogeneous environments. We studied 3 alpine populations of Eurasian red squirrels (Sciurus vulgaris), 1 living in a marginal high-elevation habitat at the edge of the species' altitudinal distribution, and 2 occurring in higher-quality habitats. Here, we investigated whether squirrels living in the marginal area differed in 2 morphological parameters (body size and body mass) and/or in the expression of 4 personality traits estimated with an open field test and a mirror image stimulation test (activity, exploration, activity-exploration, and social tendency). Furthermore, we tested whether within-individual variance of the traits (behavioral plasticity) was higher in the edge habitat. Male squirrels in the edge habitat were smaller and weighed less than in the other study areas, while among females, size-habitat relationships were less marked. These sex-specific patterns were explained by a strong association between body mass and reproductive success in female squirrels. Squirrels in the marginal habitat were more active, explorative, and had a more social personality than in the other habitats. However, in contrast to our predictions, behavioral plasticity was smaller in the marginal habitat, but only for the trait exploration. Our results suggest that animals choose the habitat that best fits their personality, and that habitat-related differences in selective pressures may shape animals' morphology.

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“…Glucocorticoids are responsible for energy mobilization and fat and protein catabolism, which can ultimately lead to changes in body condition (Angelier et al, 2007;Sapolsky et al, 2000). In case of inclement weather and limited access to food, nutritional stress usually triggers the HPA axis (Jenni-Eiermann et al, 2008;Pravosudov and Kitaysky, 2006) and the response is reflected in increased circulating cortisol concentrations, an important glucocorticoid in mammals (Haase et al, 2016;Vijayan et al, 2010;Zhang and Buck, 2022). In contrast, one hypothesis would be that species adapted to unpredictable environments, such as mountainous ones, could save energy by shutting down the HPA axis and decreasing energy mobilization.…”

Section: Introductionmentioning

confidence: 99%

Weathering the storm: Decreased activity and glucocorticoid levels in response to inclement weather in breeding Columbian ground squirrels

Tamian,

Edwards,

Neuhaus

et al. 2023

Hormones and Behavior

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Seasonal patterns in behavior and glucocorticoid secretion of a specialist Holarctic tree squirrel (Sciurus aberti)

Cited by 6 publications

References 125 publications

Long-term, medium-term and acute stress response of urban populations of Eurasian red squirrels affected by different levels of human disturbance

Long-term, medium-term and acute stress response of urban populations of Eurasian red squirrels affected by different levels of human disturbance

Living on the edge: morphological and behavioral adaptations to a marginal high‐elevation habitat in an arboreal mammal

Weathering the storm: Decreased activity and glucocorticoid levels in response to inclement weather in breeding Columbian ground squirrels

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