Cory Williams

Cory Williams
Colorado State University | CSU · Department of Biology

About

62
Publications
12,292
Reads
How we measure 'reads'
A 'read' is counted each time someone views a publication summary (such as the title, abstract, and list of authors), clicks on a figure, or views or downloads the full-text. Learn more
1,320
Citations
Additional affiliations
August 2017 - August 2021
University of Alaska Fairbanks
Position
  • Professor (Assistant)
September 2015 - August 2017
Northern Arizona University
Position
  • Professor (Assistant)
September 2012 - August 2015
University of Alaska Anchorage
Position
  • Postdoctoral Fellow - Chronobiology of arctic ground squirrels

Publications

Publications (62)
Article
Full-text available
Hibernation provides a means of escaping the metabolic challenges associated with seasonality, yet the ability of mammals to prolong or reenter seasonal dormancy in response to extreme weather events is unclear. Here, we show that Arctic ground squirrels in northern Alaska exhibited sex-dependent plasticity in the physiology and phenology of hibern...
Article
Full-text available
Tactics of resource use for reproduction are an important feature of life-history strategies. A distinction is made between ‘capital’ breeders, which finance reproduction using stored energy, and ‘income’ breeders, which pay for reproduction using concurrent energy intake. In reality, vertebrates use a continuum of capital-to-income tactics, and, f...
Article
Full-text available
In this mini-review, we discuss how biologging technology can be used to detect, understand, and forecast species' responses to climate change. We review studies of phenology, thermal biology, and microhabitat selection as examples to illustrate the utility of a biologging approach in terrestrial and aquatic species. These examples show that biolog...
Article
Full-text available
Circadian systems are principally entrained to 24h light/dark cycles, but this cue is seasonally absent in polar environments. Although some resident polar vertebrates have weak circadian clocks and are seasonally arrhythmic, the arctic ground squirrel (AGS) maintains daily rhythms of physiology and behavior throughout the summer, which includes si...
Article
Full-text available
Hibernation involves prolonged intervals of profound metabolic suppression periodically interrupted by brief arousals to euthermy, the function of which is unknown. Annual cycles in mammals are timed by a photoperiodically-regulated thyroid-hormone-dependent mechanism in hypothalamic tanycytes, driven by thyrotropin (TSH) in the pars tuberalis (PT)...
Article
Full-text available
The regulation of seasonality has been an area of interest for decades, yet global climate change has created extra urgency in the quest to understand how sensory circuits and neuroendocrine control systems interact to generate flexibility in biological timekeeping. The capacity of temperature to alter endogenous or photoperiod-regulated neuroendoc...
Article
Full-text available
Shifts in the timing of cyclic seasonal life-history events are among the most commonly reported responses to climate change, with differences in response rates among interacting species leading to phenological mismatches. Within a species, however, males and females can also exhibit differential sensitivity to environmental cues and may therefore...
Article
Full-text available
Intra- and inter-specific resource partitioning within predator communities is a fundamental component of trophic ecology, and one proposed mechanism for how populations partition resources is through individual niche variation. The Niche Variation Hypothesis (NVH) predicts that inter-individual trait variation leads to functional trade-offs in for...
Article
Hibernation is associated with long lifespan: on average, hibernating mammals live 15% longer than non-hibernators of equivalent mass. We investigated how survival varies with sex, season, and the deployment of biologgers in arctic ground squirrels [Urocitellus parryii (Richardson, 1825)], a widely-distributed northern hibernator. The duration of h...
Article
Behavioural trade-offs arise when animals must decide to engage in one behaviour at the expense of another, potentially to the animal's detriment. Here, we investigate the existence of such a trade-off by exploring the relative influence of two important behavioural processes, thermoregulation and predation avoidance, on resting behaviour in a cold...
Preprint
Full-text available
Intra- and inter-specific resource partitioning within predator communities is a fundamental component of trophic ecology, and one proposed mechanism for how populations partition resources is through individual niche variation. The Niche Variation Hypothesis (NVH) predicts that interindividual trait variation leads to functional trade-offs in fora...
Article
Full-text available
The development of animal models is a critical step for exploring the underlying pathophysiological mechanisms of major affective disorders and for evaluating potential therapeutic approaches. Although most neuropsychiatric research is performed on nocturnal rodents, differences in how diurnal and nocturnal animals respond to changing photoperiods,...
Article
Hibernation is a unique evolutionary adaptation to conserve energy. During the pre-hibernation (i.e. fall) season, a progressive decline in core body temperature and further decrease in metabolism underlie a seasonal modulation in thermoregulation. The onset of hibernation requires marked changes in thermoregulatory attributes including adjustment...
Article
The Arctic is changing rapidly, introducing new challenges and opportunities for animals. Rising air temperatures are driving dramatic shifts in habitat quality and availability, including increased shrub abundance, reduced pond area, and reduced springtime snow cover (Hinzman et al. 2005). In some cases, these changes have net positive effects for...
Article
Social interactions can shape daily activity patterns, and this is an area of growing research interest. The propensity for individuals to be active at certain times of day may structure interactions with competitors and potential mates, influencing fitness outcomes. Aspects of daily activity such as timing of activity onset and offset exhibit with...
Article
Full-text available
Bayesian stable isotope mixing models (BSIMMs) for δ13C and δ15N can be a useful tool to reconstruct diets, characterize trophic relationships, and assess spatiotemporal variation in food webs. However, use of this approach typically requires a priori knowledge on the level of enrichment occurring between the diet and tissue of the consumer being s...
Article
Describing the behaviors of free-living animals is broadly useful for ecological and physiological research, but obtaining accurate records for difficult-to-observe species presents a considerable challenge. Tri-axial accelerometers are increasingly used for this purpose by exploiting behavioral observations from accelerometer-carrying animals to p...
Article
The dynamic relationship between glucocorticoids and behavior are not well understood in wild mammals. We investigated how weather, body condition, and reproduction interact to affect cortisol levels and activity patterns in a free-living population of arctic ground squirrels (Urocitellus parryii). As a proxy for foraging and escape behaviors, coll...
Article
Hibernation is used by a variety of mammals to survive seasonal periods of resource scarcity. Reactive oxygen species (ROS) released during periodic rewarming throughout hibernation, however, may induce oxidative damage in some tissues. Telomeres, which are the terminal sequences of linear chromosomes, may shorten in the presence of ROS, and thus t...
Article
Full-text available
Synopsis The regulation of daily and circannual activity patterns is an important mechanism by which animals may balance energetic requirements associated with both abiotic and biotic variables. Using collar-mounted accelerometers, we assess the relative importance of reproductive stage and environmental conditions on the overall dynamic body accel...
Article
Thyroid hormones (TH) are key regulators of metabolism that could play an important role in altering physiology and energy allocation across life-history stages. Here, we examine seasonal TH dynamics from 345 plasma samples collected from 134 free-living arctic ground squirrels (Urocitellus parryii (Richardson, 1825)) across three consecutive years...
Article
Fisher's principle explains that population sex ratio in sexually reproducing organisms is maintained at 1 : 1 owing to negative frequency-dependent selection, such that individuals of the rare sex realize greater reproductive opportunity than individuals of the more common sex until equilibrium is reached. If biasing offspring sex ratio towards th...
Article
Full-text available
Circadian clocks are near universal among organisms and play a key role in coordinating physiological and metabolic functions to anticipate or coincide with predictable daily changes in the physical and social environment. However, whether circadian rhythms persist and are functionally important during hibernation in all mammals is currently unclea...
Article
Full-text available
Most organisms have a circadian system, entrained to daily light-dark cycles, that regulates 24-h rhythms of physiology and behavior. It is unclear, however, how circadian systems function in animals that exhibit seasonal metabolic suppression, particularly when this coincides with the long-term absence of a day-night cycle. The arctic ground squir...
Article
Stable carbon isotope ratios (δ¹³C) in breath show promise as an indicator of immediate metabolic fuel utilization in animals because tissue lipids have a lower δ¹³C value than carbohydrates and proteins. Metabolic fuel consumption is often estimated using the respiratory exchange ratio (RER), which has lipid and carbohydrate boundaries, but does n...
Article
Full-text available
Many mammals use heterothermy to meet challenges of reduced food availability and low temperatures, but little is known about the prevalence of heterothermy in wild mesocarnivores. We monitored body temperature (T b) in free-living striped skunks (Mephitis mephitis) through winter 2015–2016 in suburban Flagstaff, Arizona, a high-elevation site that...
Article
Full-text available
The sexes differ in how and when they allocate energy towards reproduction, but how this influences phenotypic plasticity in daily activity patterns is unclear. Here, we use collar-mounted light loggers and triaxial accelerometers to examine factors that affect time spent above ground and overall dynamic body acceleration (ODBA), an index of activi...
Data
Full-text available
Table S1. Parameter estimates for environmental variables Figure S1. Predicted differences between the sexes in p-splines
Article
Full-text available
Thyroid hormones (THs), key regulators of lipid and carbohydrate metabolism, are likely modulators of energy allocation within and among animal life history stages. Despite their role in modulating metabolism, few studies have investigated whether THs vary among life history stages in free-living animals or if they exhibit stage-specific relationsh...
Article
Full-text available
Article
Full-text available
Polar organisms must cope with an environment that periodically lacks the strongest time-giver, or zeitgeber, of circadian organization-robust, cyclical oscillations between light and darkness. We review the factors influencing the persistence of circadian rhythms in polar vertebrates when the light-dark cycle is absent, the likely mechanisms of en...
Article
Full-text available
Abstract Hibernation in mammals is a physiological and behavioral adaptation to survive intervals of low resource availability through profound decreases in metabolic rate (MR), core body temperature (Tb), and activity. Most small mammalian hibernators thermoconform, with Tb approximating ambient temperature (Ta); arctic species are an exception, s...
Article
Full-text available
sees sustainable scholarly publishing as an inherently collaborative enterprise connecting authors, nonprofit publishers, academic institutions, research libraries, and research funders in the common goal of maximizing access to critical research. Light loggers reveal weather-driven changes in the daily activity patterns of arboreal and semifossori...
Article
Full-text available
Mammalian hibernation is characterized by prolonged dormancy consisting of pronounced depression of metabolism and body temperature. Though hibernation occurs in at least seven mammalian orders and several families of the order Rodentia, the ecology and physiology of hibernation in rodents has been most extensively studied in the family Sciuridae,...
Article
Full-text available
The production of offspring by vertebrates is often timed to coincide with the annual peak in resource availability. However, capital breeders can extend the energetic benefits of a resource pulse by storing food or fat, thus relaxing the need for synchrony between energy supply and demand. Food-hoarding red squirrels (Tamiasciurus hudsonicus) bree...
Article
Full-text available
In territorial species, competitive asymmetries can result in the uneven distribution of food resources as high-quality individuals force young or subordinates to occupy smaller or lower-quality sites, or both. However, spatiotemporal variation in the production of resources also can influence an individual's ability to monopolize resources and, co...
Article
Full-text available
Communal nesting can help defray the high cost of endothermic heat production in cold environments, but such social behavior is generally thought to be incompatible with the persistent defense of exclusive territories in typically ‘asocial’ animals. We examined the propensity for communal nesting in female red squirrels (Tamiasciurus hudsonicus), w...
Article
Full-text available
In mammals, the circadian master clock generates daily rhythms of body temperature (T(b)) that act to entrain rhythms in peripheral circadian oscillators. The persistence and function of circadian rhythms during mammalian hibernation is contentious, and the factors that contribute to the reestablishment of rhythms after hibernation are unclear. We...
Article
Full-text available
Hibernation is a strategy of reducing energy expenditure, body temperature (T(b)) and activity used by endotherms to escape unpredictable or seasonally reduced food availability. Despite extensive research on thermoregulatory adjustments during hibernation, less is known about transitions in thermoregulatory state, particularly under natural condit...
Chapter
Full-text available
The effects of climate change on hibernating species will depend, in part, on their responsiveness to environmental cues used to adjust the seasonal timing of annual events of hibernation and reproduction. Using long-term data collected from two arctic ground squirrel populations living 20 km apart in northern Alaska, we investigate the relationshi...
Article
Full-text available
In indigenous arctic reindeer and ptarmigan, circadian rhythms are not expressed during the constant light of summer or constant dark of winter, and it has been hypothesized that a seasonal absence of circadian rhythms is common to all vertebrate residents of polar regions. Here, we show that, while free-living arctic ground squirrels do not expres...
Article
Full-text available
Precise measures of phenology are critical to understanding how animals organize their annual cycles and how individuals and populations respond to climate-induced changes in physical and ecological stressors. We show that patterns of core body temperature (T b) can be used to precisely determine the timing of key seasonal events including hibernat...
Article
Full-text available
Hibernating arctic ground squirrels (Urocitellus parryii), overwintering in frozen soils, maintain large gradients between ambient temperature (T(a)) and body temperature (T(b)) by substantially increasing metabolic rate during torpor while maintaining a subzero T(b). We used quantitative reverse-transcription PCR (qRT-PCR) to determine how the exp...
Article
Full-text available
Precise measures of phenology are critical to understanding how animals organize their annual cycles and how individuals and populations respond to climate-induced changes in physical and ecological stressors. We show that patterns of core body temperature (T b) can be used to precisely determine the timing of key seasonal events including hibernat...
Article
Full-text available
Analysis of fatty acids (FAs) is an increasingly utilized tool in studies of trophic ecology in marine ecosystems. This powerful technique has proved useful in delineating spatial and temporal variability in diets, identifying the consumption of key species, and providing quantitative estimates of diet composition. Although consumer FA signatures a...
Article
Full-text available
Seabirds have long been promoted as bio-indicators, because parameters such as reproductive success, nestling growth rates, and diet composition respond markedly to changes in food supply. Although such responses are often associated with broad-scale oceanographic phenomena, they are also influenced by processes that occur on much smaller spatial s...
Article
Full-text available
Fatty acid (FA) signature analysis is a powerful tool to investigate foraging ecology and food web dynamics in marine ecosystems. However, use of FA signatures to qualitatively or quantitatively infer diets is potentially complicated by effects of nutritional state on lipid metabolism. Estimation of diets using the quantitative fatty acid signature...
Article
Full-text available
Major breeding failures of seabird populations are sometimes attributed to reduced egg laying or abandonment of incubation due to nutritional stress, yet diets during these reproductive stages are often poorly characterized. We used stable isotopes and fatty acid (FA) signatures to infer age- (adult vs. nestling) and stage-dependent foraging niches...
Article
Corticosterone (CORT) levels in free-living animals are seasonally modulated and vary with environmental conditions. Although most studies measure total CORT concentrations, levels of corticosteroid binding globulin (CBG) may also be modulated, thus altering the concentration of CORT available for diffusion into tissues (free CORT). We investigated...
Article
Full-text available
In some species, corticosterone (CORT) appears to play a role in the control of begging behavior. Because of the potentially high costs associated with chronic elevation of CORT, it has also been proposed as a mechanism to ensure begging is an honest signal. We determined the effects of moderate food restriction (50% of high calorie treatment) on v...
Article
Full-text available
Reduced prey availability can affect the growth and survival of nestling seabirds. However, few studies have demonstrated similar effects on indices of adult body condition. We examined body condition and seasonal mass loss of breeding adult male and female Tufted Puffins (Fratercula cirrhata) at Chiniak Bay, Kodiak Island, Alaska, in 2004-2005. We...
Article
Full-text available
When using stable isotopes as dietary tracers it is essential to consider effects of nutritional state on isotopic fractionation. While starvation is known to induce enrichment of (15)N in body tissues, effects of moderate food restriction on isotope signatures have rarely been tested. We conducted two experiments to investigate effects of a 50-55%...
Article
Although radiotelemetry is useful for monitoring nest attendance and the foraging ranges and distribution of breeding birds, attachment of transmitters may affect reproductive behavior. In 2003, we captured 25 adult Tufted Puffins (Fratercula cirrhata) at two colonies in Chiniak Bay, Kodiak Island, Alaska, and fitted them with subcutaneously anchor...

Network

Cited By

Projects

Projects (2)
Project
This project is funded by the NSF and I am a collaborator on this project: Arctic ground squirrels display robust circannual rhythms of reproduction and hibernation. There is growing interest in forecasting the impact of climate change on phenology in animals. Our ability to predict how species might alter their annual timing in response to rapid environmental change is constrained, however, by increasing our knowledge regarding the endogenous mechanisms animals use to keep time, the cues used to adjust timing, and the extent to which programmed seasonal cycles are physiologically plastic we can understand the impact of climate change.