The measurement of stable isotopes in ‘bulk’ animal and plant tissues (e.g., muscle or leaf) has become an important tool for studies functional diversity from organismal to continental scales. In consumers, isotope values reflect their diet, trophic position, physiological state, geographic location. However, interpretation bulk tissue can be confounded by variation primary producer baseline overlapping among potential food items. To resolve these issues, biologists increasingly use...

Polar bears (Ursus maritimus) summer on the sea ice or, where it melts, shore. Although physiology of "ice" in is unknown, "shore" purportedly minimize energy losses by entering a hibernation-like state when deprived food. Such strategy could partially compensate for loss on-ice foraging opportunities caused climate change. However, here we report gradual, moderate declines activity and body temperature both shore summer, resembling expenditures typical fasting, nonhibernating mammals. Also,...

Abstract Recent reductions in thickness and extent have increased drift rates of Arctic sea ice. Increased ice could significantly affect the movements energy balance polar bears ( Ursus maritimus ) which forage, nearly exclusively, on this substrate. We used radio‐tracking data to quantify influence bear movements, we modeled consequences for demands adult females Beaufort Chukchi seas during two periods with different characteristics. Westward northward by both regions between 1987–1998...

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Ecologists increasingly determine the δ15 N values of amino acids (AA) in animal tissue; "source" AA typically exhibit minor variation between diet and consumer, while "trophic" have increased consumers. Thus, trophic-source offsets (i.e., Δ15 NT-S ) reflect trophic position a food web. However, even variations Nsource may influence magnitude offset that represents step, known as discrimination factor TDFT-S ). Diet digestibility protein content can bulk tissue, but effects these factors on...

The incorporation of dietary macronutrients and associated isotopic signatures carbon (δ13C) nitrogen (δ15N) into animal tissues is a result the interaction between growth, nutritional status, composition diet. In mammalian carnivores further complicated by lack carbohydrates in diet allocation large quantities to fetuses milk production. this study, we explored effects composition, pregnancy, production on 13C 15N captive mink (Neovison vison) fed 3 experimental diets (Beef, Fish, Mixture...

The application of stable isotope analysis (SIA) to the fields ecology and animal biology has rapidly expanded over past three decades, particularly with regards water analysis. SIA now provides opportunity monitor migration patterns, examine food webs, assess habitat changes in current study systems. While carbon nitrogen biological samples have become common, analyses oxygen or hydrogen are used more sparingly despite their promising utility for tracing sources metabolism. Common...

Climate change is altering the distribution of some wildlife species while warming temperatures are facilitating northward expansion pathogens, potentially increasing disease risk. Melting Arctic sea ice increasingly causing polar bears (Ursus maritimus) southern Beaufort Sea (SBS) to spend summer on land, where they may encounter novel pathogens. Here, we tested whether SBS shore during exhibited greater immune system activity than remaining ice. In addition, type response correlated with...

Although tissue fatty acid (FA) composition has been linked to whole-animal performance (e.g., aerobic endurance, metabolic rate, postexercise recovery) in a wide range of animal taxa, we do not adequately understand the pace changes FA and its implications for ecology animals. Therefore, used C4 C3 diet shift experiment compound-specific δ13C analysis estimate turnover rates FAs polar neutral fractions flight muscle lipids (corresponding membranes lipid droplets) exercised sedentary zebra...

Demographic structure is central to understanding the dynamics of animal populations. However, determining age free-ranging mammals difficult, and currently impossible when sampling with noninvasive, genetic-based approaches. We present a method estimate class by combining measures telomere lengths other biologically meaningful covariates in Bayesian network. applied this approach American Pacific martens (Martes americana M. caurina) compared predicted that obtained from counts cementum...

Capital breeders accumulate nutrients prior to egg development, then use these stores support offspring development. In contrast, income rely on local consumed contemporaneously with Understanding such nutrient allocations is critical assessing life-history strategies and habitat use. Despite the contrast between strategies, it remains challenging trace from endogenous or exogenous food intake into offspring. Here, we tested a new solution this problem. Using tissue samples collected...

Animals moving across snow surfaces sink to varying depths, increasing the energetic cost of travel. For ease movement, animals may follow compacted trails created by sports such as snowmobiling and snowshoeing. We tested assumption that less‐adapted travel (i.e. with a high footload (body mass/foot surface area)) are more likely use them for greater distances than well‐adapted on snow. sampled animal movements non‐compacted transects in northwestern Wyoming southeastern Idaho, USA, during...

When reducing activity and using stored energy during seasonal food shortages, animals risk degradation of skeletal muscles, although some species avoid or minimize the resulting atrophy while experiencing these conditions hibernation. Polar bears may be deprived relatively inactive winter (when pregnant females hibernate hunting success declines for other demographic groups) as well summer sea ice retreats from key foraging habitats). We investigated muscle in samples biceps femoris...

Abstract The dynamics of animal body water and metabolism are integral aspects biological function but difficult to measure, particularly in free-ranging individuals. We demonstrate a new method estimate inputs via analysis Δ17O, measure 17O/16O relative 18O/16O. Animal is primarily mixture drinking or food (meteoric water; Δ17O ≈ 0.030 per mille [‰]) metabolic synthesized from atmospheric oxygen (Δ17O –0.450‰). Greater intake should increase toward 0.030‰, whereas greater rate decrease...

Dietary carbon is oxidized and exhaled as CO2, thus δ13Cbreath values can provide information on diet substrate use for energy. However, physiological phenomena such fat deposition fasting alter of that interpretation source contributions may be unclear. Consequently, before application to free-ranging animals, inferences about feeding nutritional states based should validated with controlled experiments using captive individuals. Here, we report 4 brown bears (Ursus arctos) under different...

The measurement of bulk tissue nitrogen (δ15N) and carbon isotope values (δ13C) chronologically along biologically inert tissues sampled from offspring can provide a longitudinal record their mothers' foraging habits. This study tested the important assumption that mother-offspring stable are positively linearly correlated. In addition, any change in individual amino acids occurred during gestation was investigated. Whiskers southern elephant seal pups (Mirounga leonina) temporally...

Tracing how free-ranging organisms interact with their environment to maintain water balance is a difficult topic study for logistical and methodological reasons. We use novel combination of triple-oxygen stable isotope analyses extracted from plasma (δ 16 O, δ 17 18 O) bulk tissue carbon 13 C) nitrogen 15 N) isotopes feathers blood estimate the proportional contribution marine resources, seawater, metabolic used by two species unique songbirds (genus Cinclodes ) in seasonal coastal...

Understanding physiological traits and ecological conditions that influence a species reliance on metabolic water is critical to creating accurate models can assess their ability adapt environmental perturbations (e.g., drought) impact availability. However, relatively few studies have examined variation in the sources of animals use maintain balance, even fewer focused role water. A key reason methodological limitations. Here, we applied new method measures triple oxygen isotopic...