The carbon-isotope composition of hair and feces offers a glimpse into the diets mammalian herbivores. It is particularly useful for determining relative consumption browse graze in tropical environments, as these foods have strongly divergent compositions. Fecal δ 13 C values reflect last few days consumption, whereas provides longer term dietary information. Previous studies shown, however, that some fractionation occurs between those feces. Accurate reconstruction requires an...

The rate of food intake exerts an important influence on many aspects herbivore ecology, including diet and habitat choices, social organization, predator avoidance. When is spatially concentrated, short-term dry matter (I, g/min) determined largely by morphology the mouth mechanics consumption. Morphology (tooth size jaw musculature) (cropping chewing processes) are hypothesized to scale with body mass (M) for mammalian herbivores. By using a simple model processes regulating I, we...

Type II functional responses are frequently observed in herbivores feeding patches where plants concentrated space. We tested a mechanistic model of regulation intake rate foraging food—concentration (Laca and Demment 1992, Spalinger Hobbs 1992) that accounts for asymptotic, responses. The is based on the hypothesis competition between cropping chewing regulates instataneous response to changes size bites obtained by forager. this examined ability our account observations 12 species...

Energy maximization, time minimization, and linear programming models subject to various constraints have dominated foraging ecology ideas methods for decades. However, animals must use very complex physiological processes decisions ensure fitness that in many cases may not be adequately described by these approaches. An example of this problem occurs when brown bears, Ursus arctos, access both abundant salmon fruit. Salmon are one the most energy nutrient dense foods available bears. Fruits...

Understanding dietary specialization in herbivores has theoretical and practical implications ecology, yet defining niche breadth consistently been problematic. To increase clarity communication among ecologists disciplines (i.e., chemists, pharmacologists), we propose a key for mammalian that assigns "obligatory" "facultative" modifiers to the terms "specialist" "generalist". These are assigned based on (1) relative of animal's realized diet (what it eats), (2) fundamental available could...

ABSTRACT Demographic data show many populations of Rocky Mountain ( Cervus elaphus nelsoni ) and Roosevelt roosevelti elk have been declining over the last few decades. Recent work suggests that forage quality associated animal nutritional condition, particularly in late summer early autumn, influence reproduction survival elk. Therefore, we estimated seasonal condition 861 female 2,114 capture events from 21 herds Washington, Oregon, Wyoming, Colorado, South Dakota 1998 to 2007. We...

Understanding how large herbivores select their diet requires accurate measurements of the nutritional costs and benefits food items composition plants in relative to habitat. We followed moose (Alces alces) tracks snow measured bites browse taken number mass twigs 10 species available within moose's reach morphological chemical characteristics plants. The diets 41 northern coastal Sweden contained 75% Scots pine (Pinus sylvestris) willow (Salix spp.), with remaining proportion equally...

The metabolism of probe substrates phase I and II enzymes in vitro were compared hepatic subcellular fractions from humans, cynomolgus monkeys, rhesus beagle dogs. These studies undertaken to compare the suitability these species as models drug development. Eight cytochrome P450-dependent activities measured microsomal incubations: ethoxyresorufin O-deethylase, coumarin 7-hydroxylase, tolbutamide 4-hydroxylase, S-mephenytoin 4'-hydroxylase, bufuralol 1'-hydroxylase, N-nitrosodimethylamine...

The architecture of woody food plants forces mammalian herbivores to make compromises in their choices. Rapid rates dry matter intake can be achieved by choosing large bites. For plants, however, such bites are low nutritive quality relative small taken from leaves or twigs near the growing point plant. This trade-off between and rate is central diet optimization browsing herbivores. We developed a model that predicts quantitative solution 'optimal bite size' (i.e., results greatest daily...

Gemcitabine, 2'-deoxy-2',2'-difluorocytidine, is a broad spectrum oncolytic compound with antitumor activity in solid tumor models. The pharmacokinetics, metabolism, and disposition of gemcitabine was examined mice, rats, dogs. All three species metabolize by deamination to the uracil metabolite. However, mouse dog more extensive than rat. deaminated rapidly plasma concentration maximum metabolite being attained at 15 min postdosing compared approximately 3 6 hr rat, respectively. rapid also...

Organisms respond to their heterogeneous environment in complex ways at many temporal and spatial scales. Here, I examine how the smallest scale process foraging by mammalian herbivores, taking a bite, influences plants herbivores over larger First, because cropping bites competes with chewing them, bite size short‐term intake rate of within plant patches. On other hand, can chew while searching for new ones, thus influencing time spent vigilant as animals move among food Therefore, affects...

The question of how much time a foraging herbivore should spend in patch food poses central challenge classical theory. However, there remains uncertainty about the relevance paradigm to decisions by large herbivores. This paper examines evidence for successfully predicting and quantifying departure mammalian herbivores across several spatial temporal scales. Departure at fine scales are influenced tradeoffs between maximizing intake rate quality. Classical models larger scales, particularly...

ABSTRACT Recent work suggests that availability and quality of forage in late summer early autumn, a time when female ungulates face multiple energetic demands, is critical to reproduction wild ungulates. Therefore, we examined direct links between nutritional diets, body condition, lactating mule deer. Using captive deer, tested the hypothesis females consuming diets with lower digestible energy (DE; kJ/g) would have DE intake rates (DEI; MJ/day), less fat muscle, later estrus cycles,...

Abstract An animal's ability to avoid predation likely depends on its detect approaching predators, conceal itself, and seek refuge or protection from predators. Habitat, especially vegetation structure, can influence all of these factors concurrently. Binary categorical assessments habitat as ‘open’ ‘closed’, however, confound at least two functions structure that could the perceived risk predation: concealment, which hide an individual, visibility, enhances detection a potential predator....

Abstract Contemporary techniques predicting habitat suitability under climate change projections often underestimate availability of thermal refuges. Habitat structure contributes to heterogeneity at a variety spatial scales, but quantifying microclimates organism‐relevant resolutions remains challenge. Landscapes that appear homogeneous large scales may offer patchily distributed refuges finer scales. We quantified the relationship between vegetation and environment scale relevant small,...

Rocky land cover provides vital habitat for many different species, including endemic, vulnerable, or threatened plants and animals; thus, various management organizations prioritize the conservation of rocky habitat. Despite its importance, classification maps rarely classify explicitly, if they do, are limited in spatial resolution extent. Consequently, we used random forest models Google Earth Engine (GEE) to at a high across broad extent Cascade Mountains Columbia River Gorge Washington,...

There appear to be two dominant forms of the functional response vertebrate herbivores, corresponding animals foraging in spatially concentrated or dispersed food patches. We examine factors contributing herbivores feeding on browses. Specifically, we tested hypothesis that instantaneous intake rate four boreal browsers (moose, Alces alces, woodland caribou, Rangifer tarandus white-tailed deer, Odocoileus virginianus, and snowshoe hares, Lepus americanus) red maple (Acer rubrum) browse is an...

Abstract: We developed new, and validated existing, indices of nutritional condition for live dead mule deer ( Odocoileus hemionus ). Live animal included a body score (BCS), thickness subcutaneous fat selected muscles using ultrasonography, mass. Dead femur, metatarsal, mandible marrow fat, 3 kidney indices, 2 carcass scoring methods. used 21 female 4 castrates (1‐11 yr old) varying widely in (2‐28% ingesta‐free fat). Deer were euthanized homogenized chemical analysis protein, water, ash...

For herbivores, nutrient intake is limited by the relatively low nutritional quality of plants and high concentrations potentially toxic defensive compounds (plant secondary metabolites, PSMs) produced many plants. In response to phytochemical challenges, some herbivores selectively forage on with higher lower PSM relative other Pygmy rabbits (Brachylagus idahoensis) are dietary specialists that feed sagebrush (Artemisia spp.) specific more than others within a foraging patch. We predicted...

Olfactory communication among mammals remains poorly studied yet may be key to understanding their ecology. This is particularly true for mammalian carnivores, which rely extensively on scent marking communication. Previous research suggests that carnivore latrines play a large role in both intra- and interspecific Despite the apparent complexity of mammal use latrines, little work has examined behavior patterns species visit latrines. We used motion-triggered video cameras study at ocelot...

Heterogeneous vegetation structure can create a variable landscape of predation risk—a fearscape—that influences the use and selection habitat by animals. Mapping functional properties that influence risk (e.g., concealment visibility) across landscapes be challenging. Traditional ground-based measures are location specific limited in spatial resolution. We demonstrate benefits terrestrial laser scanning (TLS) to map shape fearscapes. used TLS data estimate prey from multiple vantage points,...

Large terrestrial mammals increasingly rely on human-modified landscapes as anthropogenic footprints expand. Land management activities such timber harvest, agriculture, and roads can influence prey population dynamics by altering forage resources predation risk via changes in habitat, but these effects are not well understood regions with diverse changing predator guilds. In northeastern Washington state, USA, white-tailed deer (Odocoileus virginianus) vulnerable to multiple carnivores,...