A5030436966- Animal Ecology and Behavior Studies
- Wildlife Ecology and Conservation
- Bat Biology and Ecology Studies
- Animal Behavior and Reproduction
- Ecology and Vegetation Dynamics Studies
- Neuroendocrine regulation and behavior
- Animal Behavior and Welfare Studies
- Species Distribution and Climate Change
- Stress Responses and Cortisol
- Plant and animal studies
- Physiological and biochemical adaptations
- Ecology and biodiversity studies
- Rangeland and Wildlife Management
- Fire effects on ecosystems
- Effects of Environmental Stressors on Livestock
- Genetic diversity and population structure
- Avian ecology and behavior
- Tree-ring climate responses
- Marine animal studies overview
- Isotope Analysis in Ecology
- Primate Behavior and Ecology
- Neurogenesis and neuroplasticity mechanisms
- Birth, Development, and Health
- Evolutionary Psychology and Human Behavior
- Indigenous Studies and Ecology
The Scarborough Hospital
2015-2024
University of Toronto
2015-2024
University of British Columbia
1978-2021
University of Alberta
1987-2021
University of Florida
2021
United States Geological Survey
2021
Eastern Ecological Science Center
2021
John Wiley & Sons (United States)
2018
Ecological Society of America
2018
Western University
2010
Snowshoe hare populations in the boreal forests of North America go through 10-year cycles. Supplemental food and mammalian predator abundance were manipulated a factorial design on 1-square-kilometer areas for 8 years Yukon. Two blocks forest fertilized to test nutrient effects. Predator exclosure doubled addition tripled density during cyclic peak decline. combined with increased 11-fold. Added nutrients plant growth but not density. Food predation together had more than additive effect,...
The sublethal effects of high predation risk on both prey behavior and physiology may have long-term consequences for population dynamics. We tested the hypothesis that snowshoe hares during decline are chronically stressed because whereas those low not, this has negative their demography. Snowshoe exhibit 10-yr cycles; declines, virtually every hare dies is killed by a predator. assessed physiological responsiveness stress axis energy mobilization subjecting to hormonal-challenge protocol....
1. Prey responses to high predation risk can be morphological or behavioural and ultimately come at the cost of survival, growth, body condition, reproduction. These sub-lethal predator effects have been shown mediated by physiological stress. We tested hypothesis that elevated glucocorticoid concentrations directly cause a decline in reproduction individual free-ranging female snowshoe hares, Lepus americanus. measured cortisol concentration from each dam (using faecal analysis enzyme...
Summary Chronic activation of the stress axis caused by long‐term uncontrollable and unpredictable factors in environment has been regarded as causing maladaptive and/or pathological effects, both those studying animals laboratory nature. While pathology may apply to former, I argue that it does not latter. Our thinking on role chronic nature heavily influenced biomedical research, but much less so ecological evolutionary context within which actually function. when such stressors occur...
Conservation physiology proposes that measures of physiological stress (glucocorticoid levels) can be used to assess the status and future fate natural populations. Increases in glucocorticoids may reflect a more challenging environment, suggesting influence human activities on free-living animals could quantified by measuring glucocorticoids. Biomedical studies suggest chronic increases have detrimental effects survival reproduction, which viability Here, we discuss use measurements...
In fluctuating environments, mothers may enhance the fitness of their offspring by adjusting phenotypes to match environment they will experience at independence. free-ranging red squirrels, natural selection on postnatal growth rates varies according population density, with favoring faster-growing under high-density conditions. We show that exposing cues, accomplished via playbacks territorial vocalizations, led increased in absence additional food resources. Experimental elevation actual...
Summary Our goal in this review is to discuss how measures beyond simple quantification of total glucocorticoid levels are needed comparative studies stress. We need measure corticosteroid binding globulin – CBG and further downstream performance metrics properly evaluate the significance impact stress wild populations. briefly cover current literature, methods that may enable detection chronic point directions for future research continue clarify field. regulate access hormones tissues, but...
n 1831 the manager of a Hudson’s Bay Company post in northern Ontario wrote to head office London. The local Ojibway Indians were starving, he reported, because scarcity “rabbits,” and they unable trap for furs spent all their time fishing food (Winterhalder 1980). These shortages so-called rabbits, which apparently occurred approximately every 10 years, are regularly mentioned Canadian historical documents from 18th 19th centuries. Those rabbits fact snowshoe hares (Lepus americanus),...
The never-ending tension between finding food and avoiding predators may be the most universal natural stressor wild animals experience. 'chronic stress' hypothesis predicts: (i) an animal's stress profile will a simultaneous function of predator pressures given aforesaid tension; (ii) these inseparable effects on physiology produce demography because resulting adverse health effects. This was originally proposed to explain synergistic (inseparable) in snowshoe hares (Lepus americanus). We...
Across the boreal forest of Canada, lynx populations undergo regular density cycles. Analysis 21 time series from 1821 onward demonstrated structural similarity in these cycles within large regions Canada. The observed population dynamics are consistent with a regional structure caused by climatic features, resulting grouping into three types (corresponding to climatic-based geographic regions): Pacific-maritime, Continental, and Atlantic-maritime. A possible link North Atlantic Oscillation...
We measured the density changes of 22 species vertebrates during a snowshoe cycle in northern Canada. Hares were dominant herbivore system and their numbers correlated with arctic ground squirrel, spruce grouse, ptarmigan, lynx, coyote, great horned owl, goshawk, raven hawk owl. Hare not red-backed vole which showed peaks low, increase, early decline phases hare cycle. Hawk owls only predator whose voles while boreal weasels densities Microtus. Red American kestrel, red-tailed hawk, harrier,...
Maternal effects may be a major factor influencing the demography of populations. In mammals, transmission stress hormones between mother and offspring play an important role in these effects. Laboratory studies have shown that stressors during pregnancy lactation result lifelong programming phenotype. However, relevance to free-living mammals is unclear. The 10-year snowshoe hare (Lepus americanus) cycle intimately linked fluctuating predation pressure risk. enigma cycles lack population...
Habitat constrains and shapes successful ecological physiological strategies thus provides the context for evolution of life-history traits. The stress axis plays a vital role in endocrine system is critical component adapting mammals to particular habitat pressures. It subject both individual activational organizational plasticity as well evolutionary modification. To illustrate, I examine suite traits associated with breeding frequency male mammals, which varies continuum from semelparity...
Mark–recapture methods produce more accurate estimates when a high fraction of the population is trapped. Three trappability are used in literature, and we compare them for four species Microtus livetrapped Longworth traps. The trappable defined by weight at first capture varies greatly different species. Jolly best estimate on average 4% above minimum 8% below maximum trappability. Trappability seasonally, lowest summer, may be reduced densities. Females are, average, 2% than males. same...
Predator-induced changes in physiology and behaviour may negatively affect a prey's birth rate. Evidence of such indirect predator effects on prey demography remains scarce birds mammals despite invertebrate aquatic studies that suggest ignoring risks profoundly underestimating the total impact predators. We report first experimental demonstration annual 'birth' rate resulting from negative size subsequent clutches laid by birds. manipulated probability nest predation measured multiple...
Bacterial diversity within animals is emerging as an essential component of health, but it unknown how stress may influence the microbiome. We quantify a proximate link between oral microbiome and hypothalamic–pituitary–adrenal (HPA) axis activity using faecal glucocorticoid metabolites (FGM) in wild red squirrels ( Tamiasciurus hudsonicus ). Not only was bacterial lower at higher levels FGM, also capture periods change relative abundance related to increase FGM. These linkages HPA...