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1. Nutrition influences most aspects of animal ecology: juvenile growth rates and adult mass gain, body condition, probability of pregnancy, over-winter survival, timing of parturition, and neonatal birth mass and survival. We provide an overview among ungulates of the extent of these influences resulting from interactions among bioenergetics, foraging, and nutritional demands. 2. Body condition of an animal is the integrator of nutritional intake and demands, affecting both survival and reproduction. The deposition and mobilization of body fat and body protein vary with physiological requirements and environmental conditions as species use dietary income and body stores to integrate the profits of summer and the demands of winter. Results from our simulation model and uncertainty analysis of the influence of body mass and changes in body composition of Rangifer over winter indicate that percent body fat rather than body mass in early winter is most important in determining whether animals die, live without reproducing, or live and reproduce. Animal responses are also sensitive to rates of change in body protein. Depending on timing of calving and maternal reserves, seasonal habitats vary in their nutritional value for the production of offspring. 3. For free-ranging animals, life is a balance among numerous ecological factors, including nutritional requirements, nutritional resources to meet those demands, and intra- and inter-specific interactions. Predation effects on population demography may mask nutritional limitations of habitat. We suggest that over the long term of life histories, ungulates use seasonal strategies that minimize the maximum detriment, and that the basis for most strategies is nutritional.

Adaptive management is a powerful means of learning about complex ecosystems, but is rarely used for recovering endangered species. Here, we demonstrate how it can benefit woodland caribou, which became the first large mammal extirpated from the contiguous United States in recent history. The continental scale of forest alteration and extended time needed for forest recovery means that relying only on habitat protection and restoration will likely fail. Therefore, population management is also needed as an emergency measure to avoid further extirpation. Reductions of predators and overabundant prey, translocations, and creating safe havens have been applied in a design covering >90,000 km². Combinations of treatments that increased multiple vital rates produced the highest population growth. Moreover, the degree of ecosystem alteration did not influence this pattern. By coordinating recovery involving scientists, governments, and First Nations, treatments were applied across vast scales to benefit this iconic species.

ContextAnthropogenic linear features can have negative effects on wildlife by altering movements or increasing risk. Spatial responses to linear features vary depending on local conditions (functional responses), including linear feature availability. Several studies explored functional responses of wildlife to linear features, but few examined responses of multiple interacting species.ObjectivesWe evaluated functional responses of Threatened boreal woodland caribou (Rangifer tarandus caribou), moose (Alces alces), and gray wolves (Canis lupus) to roads and seismic lines (linear features created during fossil fuel exploration) to assess the influence these responses might have on predator–prey interactions.MethodsWe estimated median distance to and the density of roads and seismic lines around used and available locations by landcover (peatlands and non-peatlands) and season for each individual. To quantify functional responses, we regressed use in response to availability in peatlands and non-peatlands across seasons and selected the most parsimonious models for each species.ResultsBoreal caribou generally avoided higher road density. Wolves selected areas closer to roads in peatlands and demonstrated selection or indifference to higher road density as availability increased. Female moose generally avoided areas with higher road density, except in early winter. Female caribou and moose demonstrated weaker responses to seismic line density. During calving, late summer, and early winter, wolves often selected for seismic line density, particularly in peatlands, when availability was high.ConclusionsOur analyses suggest that boreal caribou, moose, and wolves respond to linear features in complex ways that alter individual space-use and likely influence predation risk.

Climate change is predicted to increase the frequency and size of wildfires. Wildfire burns can influence wildlife space use, but prior to understanding the relationship between wildlife and burns, the extent of wildfires and the regrowth of burned areas must be determined. We used remotely sensed, multispectral satellite imagery to calculate differenced normalized burn ratios (NBRs) to define areas burned by wildfire and assess temporal trends in burn frequency and extent in central British Columbia. We then used NBRs as an index of vegetation regrowth to model regrowth trajectories within burns. Next, we examined spatial responses to burns by a moose (Alces alces) population that recently declined in abundance. We utilized locations used by and available to collared moose to determine spatial responses as a function of years since wildfire and vegetation regrowth. We also assessed functional responses to burns by moose, dependent upon the proportion of burned areas available to each individual. We hypothesized that (h1) wildfire burns within our study area increased from 1985 to 2017, (h2) that moose increase their use of burns in comparison with availability as burns age as a result of vegetation regrowth, and (h3) that moose demonstrate functional responses to burns (i.e., selection of burns by individual moose declines as the amount of burned areas increases). We observed that the frequency and extent of burns are increasing within our study area. In contrast to h2, moose in summer and fall decreased the selection of burns as burns aged. We, however, observed that moose responded most positively to locations with intermediate vegetation regrowth (i.e., NBR values), which according to burn regrowth trajectories were most likely to be achieved 13 or more years post‐wildfire; given that most burns within our study area were ≤13 years of age, we predict that the use of burns will likely increase as vegetation regrows. Moose only selected for burns in fall, and we did not find support for the presence of a functional response. Our research demonstrated the utility of remotely sensed imagery and NBRs to define burn locations and to reveal current and probable future spatial responses to burns by a wildlife population of concern.

Foraging by animals is hypothesized to be state-dependent, that is, varying with physiological condition of individuals. State often is defined by energy reserves, but state also can reflect differences in nutritional requirements (e.g., for reproduction, lactation, growth, etc.). Testing hypotheses about state-dependent foraging in ungulates is difficult because fine-scale data needed to evaluate these hypotheses generally are lacking. To evaluate whether foraging by caribou (Rangifer tarandus) was state-dependent, we compared bite and intake rates, travel rates, dietary quality, forage selection, daily foraging time, and foraging strategies of caribou with three levels of nutritional requirements (lactating adults, nonlactating adults, subadults 1–2 years old). Only daily foraging times and daily nutrient intakes differed among nutritional classes of caribou. Lactating caribou foraged longer per day than nonlactating caribou—a difference that was greatest at the highest rates of intake, but which persisted even when intake was below requirements. Further, at sites where caribou achieved high rates of intake, caribou in each nutritional class continued foraging even after satisfying daily nutritional requirements, which was consistent with a foraging strategy to maximize energy intake. Foraging time by caribou was partially state-dependent, highlighting the importance of accounting for physiological state in studies of animal behavior. Fine-scale foraging behaviors may influence larger-scale behavioral strategies, with potential implications for conservation and management.

Fire is the dominant single natural disturbance influencing northern mountain and boreal landscapes. We evaluated fire-induced changes in forage resources for 2 focal ungulates, Stone’s sheep (Ovis dalli stonei) and elk (Cervus canadensis), in northern British Columbia, Canada. We implemented 4 prescribed fires and monitored short-term vegetation (quantity and quality) and ungulate (Stone’s sheep and elk) responses. We took measurements prior to burning, the year of burning, and 1 year after burning in treatment areas and adjacent unburned control areas in winter and summer at 2 scales. At a fine scale, we used vegetation transects and pellet counts; at the landscape scale, we used Landsat imagery for vegetation and aerial survey flights for animals. Following prescribed fire, shrub cover declined and burned communities increased in herbaceous cover. Plant species diversity also declined but increased to almost that of unburned areas by 1 year after burning. Burning increased quality of forage most (2–7 percentage points more digestibility and 0.3–6.3 percentage points more crude protein than unburned areas) in the summer of the burn. In winter, forage biomass and available digestible dry matter increased to pre-burn levels by 1 year after burning. Stone’s sheep and elk always used burned areas more than unburned control areas in winter at both scales. Whereas elk used sites with higher forage quantity, Stone’s sheep appeared to respond to forage quality at the fine scale. Ungulate grazing during the 2 years of this study did not alter forage quantity on burned or unburned sites, as determined from range exclosures. Based on our findings in this area, maximum benefits to elk would be achieved from large prescribed fires on south-aspect slopes that result in the greatest amounts of forage biomass. Smaller prescribed fires at high burn intensities on west-aspect slopes intermixed with rocky outcrops and talus scree (less frequented by elk) would most benefit Stone’s sheep requirements for high-quality forage and escape terrain.

Predation risk is a driver of species’ distributions. Animals can increase risk avoidance in response to fluctuations in predation risk, but questions remain regarding individual variability and the capacity to respond to changes in spatial risk across human‐altered landscapes. In northeast British Columbia, Canada, boreal caribou populations declined as roads and seismic lines have increased, which are theorized to increase gray wolf predation. Our goal was to model risk and to evaluate individual variability and the development of risk perception by examining individual risk avoidance in response to reproductive status and age. We used locations from collared caribou and wolves to identify landscape features associated with the risk of a potential wolf‐caribou encounter and risk of being killed given an encounter. We built resource selection functions to estimate individual responses to risk. We used general linear regressions to evaluate individual risk and linear feature avoidance as a function of age and reproductive status (calf or no calf). Linear features increased the risk of encounter. Older caribou and caribou with calves demonstrated stronger avoidance of the risk of encounter and roads, but weaker avoidance in late summer to the risk of being killed relative to younger and calf‐less individuals. Mechanisms explaining the inverse relationships between the risk of encounter and risk of being killed are uncertain, but it is conceivable that caribou learn to avoid the risk of encounter and roads. Responses by females with vulnerable calves to the risk of encounter and risk of being killed might be explained by a trade‐off between these two risk types and a prioritization on the risk of encounter. Despite the capacity to alter their responses to risk, the global decline in Rangifer populations (caribou and wild reindeer) suggests these behaviors are insufficient to mitigate the impacts of anthropogenic disturbances. Boreal caribou (Rangifer tarandus) demonstrate individual variation in their responses to predation risk and roads as a function of age and reproductive status (calf or no calf). It is conceivable that caribou with age learn to avoid risky areas, but other explanations are also plausible. Despite the capacity to alter their responses to risk, the global decline in Ranger (caribou and reindeer) populations suggests these behaviors are insufficient to mitigate the impacts of anthropogenic disturbances.

[This corrects the article DOI: 10.1093/jmammal/gyaa003.].[This corrects the article DOI: 10.1093/jmammal/gyaa003.].

1. Macroparasites may be a major factor shaping animal behaviour. Tundra ecosystems inhabited by caribou and reindeer (Rangifer tarandus) are known for large concentrations of ectoparasites including mosquitoes (Culicidae) and black flies (Simuliidae), as well as endoparasitic oestrid flies (Oestridae). 2. Increased intensity and duration of insect harassment because of climatic warming is hypothesized as a potential factor in recent declines of Rangifer across the circumpolar north. Although there is a well-observed relationship between insect harassment and caribou/reindeer behaviour, the influence of ecto-relative to endoparasitic species is unclear. Climatic changes may favour the activity patterns, distribution or abundance of certain insect species; thus, understanding differential effects on the behaviour of Rangifer is important. 3. We recorded caribou behaviour using group scan and focal sampling methods, while simultaneously trapping insects and recording weather conditions on the postcalving/summer range of the Bathurst barren-ground caribou herd in Northwest Territories and Nunavut, Canada, during 2007-2009. 4. We developed statistical model sets representing hypotheses about the effects of insects, weather, habitat/location, and date/time on caribou behaviour. We used multinomial logistic regression models to explore factors affecting the relative dominance of behaviour types within groups of caribou and fractional multinomial logistic regression models to determine factors influencing time allocation by individual caribou. We examined changes in feeding intensity using fractional logistic regression. 5. Relative dominance of insect avoidance behaviour within caribou groups and time allocation to insect avoidance by individual caribou increased when oestrid flies were present or black flies were active at moderate-high levels. Mosquito activity had relatively little effect on caribou behaviour. Time spent feeding was reduced by the greatest degree when all three insect types were present in combination. Feeding intensity was influenced to a greater extent by the accumulation of growing degree days over the course of the postcalving/summer season than by insect activity. Changes in Arctic systems that increase the activity/abundance of ecto-and endoparasites could have implications for the productivity of Rangifer populations.