FIFTY YEARS OF FOOD AND FORAGING IN MOOSE: LESSONS IN ECOLOGY FROM A MODEL HERBIVORE

For more than half a century, biologists have intensively studied food habits and forag­ing behavior of moose (Alces alces) across their circumpolar range. This focus stems, in part, from the economic, recreational, and ecosystem values of moose, and because they are relatively easy to observe. As a result of this research effort and the relatively simple and intact ecosystems in which they often reside, moose have emerged as a model herbivore through which many key ecological ques­tions have been examined. First, dietary specialization has traditionally been defined solely based on a narrow, realized diet (e.g., obtaining >60% of its diet from 1 plant genus). This definition has not been particularly useful in understanding herbivore adaptations because >99% of mammalian herbi­vores are thus classified as generalists. Although moose consume a variety of browses across their range, many populations consume 50-99% of their diets from 1 genus (e.g., Salix). Like obligatory herbivores, moose have demonstrated adaptations to the chemistry and morphology of their nearly monospecific diets, which precludes them from eating large amounts of grass and many forbs. New classifications for dietary niche suggest that moose fit on the continuum between facultative special­ists and facultative generalists. Second, moose have been the subject of early and influential models predicting foraging behavior based on the tradeoffs between quality and quantity in plants. Subsequent models have predicted the size of stems selected by moose based on the tradeoffs between fast harvest­ing (large twigs) and quick digestion (small twigs). Because of their size, moose require many hours to harvest food, often selecting large bites as browse density declines. Finally, long-term monitoring of moose populations has provided evidence of how populations and communities are regulated. Low reproductive rates and long-term population trends shaped by moose density and forage availability on Isle Royale suggest a strong bottom-up effect on moose populations. Empirical data and simulation models suggest that moose may shape their own forage supply, influencing their community and their own populations, especially when large predators are scarce. Likewise, predation is the primary fac­tor affecting calf survival and thus moose populations in Alaska, demonstrating the important role of top-down factors. Moose will continue to provide a model for examining ecological questions such as tolerances for plant chemistry, what governs animal movements over landscapes, and reciprocal interactions between predation and reproduction

Temporal and Spatial Variation of Nitrogen in Wyoming Big Sagebrush

Sagebrush steppe systems represent one of North America’s greatest conservation challenges. Shrinking habitat and declining animal populations have prompted researchers to fill gaps in our understanding of the ecology of this system, particularly at a scale relevant to individual animals. What animals eat and why are fundamental questions linked to habitat quality and use. We investigated the temporal and spatial heterogeneity of the dietary quality of food to better understand habitat use by a sagebrush specialist, the pygmy rabbit (Brachylagus idahoensis). Within a foraging patch, pygmy rabbits selectively browse on individual Wyoming big sagebrush (Artemisia tridentata wyomingensis) that are high in nitrogen. Therefore, we hypothesized that variation in nitrogen would influence habitat use by pygmy rabbits at the patch scale. As a first step to test this hypothesis, we investigated the temporal and spatial variation in nitrogen content of patches of sagebrush within a study site in southcentral Idaho. Nitrogen concentration was determined using the Kjeldahl method. We used multivariate analysis of variance to test for differences in nitrogen content among three months within the winter season (November, January, and March) and between patches of sagebrush on mounds with deeper soils where pygmy rabbits burrow (on-mound) versus patches of sagebrush in shallower soils adjacent to mounds (off-mound). We found that nitrogen content of sagebrush was temporally and spatially dynamic. For both on- and off-mound plants, nitrogen content was significantly higher in March than November. Regardless of season, nitrogen content was significantly higher in plants on mounds compared to off-mound plants. Understanding the phenology and spatial heterogeneity of nitrogen content will help ecologists better assess diet quality and habitat quality within and among landscapes and seasons. Moreover, effective management and restoration efforts of sagebrush depend upon understanding patterns in nutrient availability to pygmy rabbits and other sagebrush specialists

Seasonal temperature acclimatization in a semi-fossorial mammal and the role of burrows as thermal refuges.

Small mammals in habitats with strong seasonal variation in the thermal environment often exhibit physiological and behavioral adaptations for coping with thermal extremes and reducing thermoregulatory costs. Burrows are especially important for providing thermal refuge when above-ground temperatures require high regulatory costs (e.g., water or energy) or exceed the physiological tolerances of an organism. Our objective was to explore the role of burrows as thermal refuges for a small endotherm, the pygmy rabbit (Brachylagus idahoensis), during the summer and winter by quantifying energetic costs associated with resting above and below ground. We used indirect calorimetry to determine the relationship between energy expenditure and ambient temperature over a range of temperatures that pygmy rabbits experience in their natural habitat. We also measured the temperature of above- and below-ground rest sites used by pygmy rabbits in eastern Idaho, USA, during summer and winter and estimated the seasonal thermoregulatory costs of resting in the two microsites. Although pygmy rabbits demonstrated seasonal physiological acclimatization, the burrow was an important thermal refuge, especially in winter. Thermoregulatory costs were lower inside the burrow than in above-ground rest sites for more than 50% of the winter season. In contrast, thermal heterogeneity provided by above-ground rest sites during summer reduced the role of burrows as a thermal refuge during all but the hottest periods of the afternoon. Our findings contribute to an understanding of the ecology of small mammals in seasonal environments and demonstrate the importance of burrows as thermal refuge for pygmy rabbits

Risk of severe intraventricular haemorrhage in the first week of life in preterm infants transported before 72 hours of age

Objectives: Evaluate the risk of severe intraventricular hemorrhage, in the first week of life, in preterm infants undergoing early interhospital transport.Design: Retrospective cohort study.Setting: Tertiary neonatal centers of the Trent Perinatal Network in the United Kingdom.Patients: Preterm infants less than 32 weeks gestation, who were either born within and remained at the tertiary neonatal center (inborn), or were transferred (transported) between centers in the first 72 hours of life.Interventions: None.Measurements and Main Results: Multivariable logistic regression models adjusting for key confounders were used to calculate odds ratios for intraventricular hemorrhage with 95% CIs for comparison of inborn and transported infants. Cranial ultrasound findings on day 7 of life. Secondary analyses were performed for antenatal steroid course and gestational age subgroups. A total of 1,047 preterm infants were included in the main analysis. Transported infants (n = 391) had a significantly higher risk of severe (grade III/IV) intraventricular hemorrhage compared with inborns (n = 656) (9.7% vs 5.8%; adjusted odds ratio, 1.69; 95% CI, 1.04–2.76), especially for infants born at less than 28 weeks gestation (adjusted odds ratio, 1.83; 95% CI, 1.03–3.21). Transported infants were less likely to receive a full antenatal steroid course (47.8% vs 64.3%; p < 0.001). A full antenatal steroid course significantly decreased the risk of severe intraventricular hemorrhage irrespective of transport status (odds ratio, 0.33; 95% CI, 0.2–0.55). However, transported infants less than 28 weeks gestation remained significantly more likely to develop a severe intraventricular hemorrhage despite a full antenatal steroid course (adjusted odds ratio, 2.84; 95% CI, 1.08–7.47).Conclusions: Preterm infants transported in the first 72 hours of life have an increased risk of early-life severe intraventricular hemorrhage even when maternal antenatal steroids are given. The additional burden of postnatal transport could be an important component in the pathway to severe intraventricular hemorrhage. As timely in-utero transfer is not always possible, we need to focus research on improving the transport pathway to reduce this additional risk

ACTIVITY PATTERNS, FORAGING ECOLOGY, AND SUMMER RANGE CARRYING CAPACITY OF MOOSE (ALCES ALCES SHIRASI) IN ROCKY MOUNTAIN NATIONAL PARK, COLORADO

To ensure sustainable populations of native animals and plants, managers of protected areas must understand carrying capacity of large wild herbivores. Estimates of carrying capacity and how large herbivores may influence native vegetation require knowledge of their activity and forag&shy;ing patterns. Therefore, we examined activity patterns and foraging behavior of adult male moose (Alces alces shirasi) in Rocky Mountain National Park, Colorado by following individual animals and counting bites during the summer and fall of 2003 and 2004. Mean active time per day peaked in late June at 11.3 h and declined to 8.9 h in early fall preceding the breeding season. Moose averaged 6.7 feeding periods/d, each lasting 79 min; feeding bouts were longer around sunrise and sunset and were shorter midday presumably because of high ambient temperature. Activities associated with feeding and resting constituted 94.0% of daily time budgets. Feeding declined and social behavior and move&shy;ment increased in fall with the onset of the breeding season. Food consumption increased steadily through early summer peaking at 126.8 g/kg BW0.75 in early August, followed by a sharp decline to a low of 69.1 g/kg BW0.75 in early September. Daily digestible energy intake was estimated at 1191 kJ/kg BW0.75/d. Maximum rates of instantaneous intake were recorded in early August at 22.3 g/min. Because intake rates of willow (Salix spp.) increased from June-August, but nutritional quality peaked in mid-June, increases in daily and instantaneous intake rates during summer seemed more related to forage availability than protein and energy content of willow leaves. The nutritional carrying capacity of summer range in Rocky Mountain National Park in 2004 was estimated from the range supply of metabolizable energy, digestible energy, and available nitrogen. Based on the digestible energy intake and energy requirements of a 344 kg male moose, the summer range carrying capacity was estimated at 0.21 moose/km2. Nitrogen based estimates were considerably higher at 0.32 moose/km2

Understanding Tradeoffs Between Food and Predation Risks in a Specialist Mammalian Herbivore

Understanding habitat use by animals requires understanding the simultaneous tradeoffs between food and predation risk within a landscape. Quantifying the synergy between patches that provide quality food and those that are safe from predators at a scale relevant to a foraging animal could better reveal the parameters that influence habitat selection. To understand more thoroughly how animals select habitat components, we investigated tradeoffs between diet quality and predation risk in a species endemic to sagebrush Artemisia spp. communities in North America, the pygmy rabbitBrachylagus idahoensis. This species is a rare example of a specialist herbivore that relies almost entirely on sagebrush for food and cover. We hypothesized that pygmy rabbits would forage in areas with low food risk (free of plant secondary metabolites, PSMs) and low predation risk (high concealment). However, because of relatively high tolerance to PSMs in sagebrush by pygmy rabbits, we hypothesized that they would trade off the risk of PSM-containing food to select lower predation risk when risks co-occurred. We compared food intake of pygmy rabbits during three double-choice trials designed to examine tradeoffs by offering animals two levels of food risk (1,8-cineole, a PSM) and predation risk (concealment cover). Rabbits ate more food at feeding stations with PSM-free food and high concealment cover. However, interactions between PSMs and cover suggested that the value of PSM-free food could be reduced if concealment is low and the value of high concealment can decrease if food contains PSMs. Furthermore, foraging decisions by individual rabbits suggested variation in tolerance of food or predation risks

Fearscapes: Mapping Functional Properties of Cover for Prey with Terrestrial LiDAR

Heterogeneous vegetation structure can create a variable landscape of predation risk—a fearscape—that influences the use and selection of habitat by animals. Mapping the functional properties of vegetation that influence predation risk (e.g., concealment and visibility) across landscapes can be challenging. Traditional ground-based measures of predation risk are location specific and limited in spatial resolution. We demonstrate the benefits of terrestrial laser scanning (TLS) to map the properties of vegetation structure that shape fearscapes. We used TLS data to estimate the concealment of prey from multiple vantage points, representing predator sightlines, as well as the visibility of potential predators from the locations of prey. TLS provides a comprehensive data set that allows an exploration of how habitat changes may affect prey and predators. Together with other remotely sensed imagery, TLS could facilitate the scaling up of fearscape analyses to promote the management and restoration of landscapes

Modeling Trade-Offs Between Plant Fiber and Toxins: A Framework for Quantifying Risks Perceived by Foraging Herbivores

When selecting habitats, herbivores must weigh multiple risks, such as predation, starvation, toxicity, and thermal stress, forcing them to make fitness trade-offs. Here, we applied the method of paired comparisons (PC) to investigate how herbivores make trade-offs between habitat features that influence selection of food patches. The method of PC measures utility and the inverse of utility, relative risk, and makes trade-offs and indifferences explicit by forcing animals to make choices between two patches with different types of risks. Using a series of paired-choice experiments to titrate the equivalence curve and find the marginal rate of substitution for one risk over the other, we evaluated how toxin-tolerant (pygmy rabbit Brachylagus idahoensis) and fiber-tolerant (mountain cottontail rabbit Sylviagus nuttallii) herbivores differed in their hypothesized perceived risk of fiber and toxins in food. Pygmy rabbits were willing to consume nearly five times more of the toxin 1,8-cineole in their diets to avoid consuming higher levels of fiber than were mountain cottontails. Fiber posed a greater relative risk for pygmy rabbits than cottontails and cineole a greater risk for cottontails than pygmy rabbits. Our flexible modeling approach can be used to (1) quantify how animals evaluate and trade off multiple habitat attributes when the benefits and risks are difficult to quantify, and (2) integrate diverse risks that influence fitness and habitat selection into a single index of habitat value. This index potentially could be applied to landscapes to predict habitat selection across several scales

A Youth-Leader Program in Baltimore City Recreation Centers: Lessons Learned and Applications

Peer-led interventions may be an effective means of addressing the childhood obesity epidemichowever, few studies have looked at the long-term sustainability of such programs. As part of a multilevel obesity prevention intervention, B'More Healthy Communities for Kids, 16 Baltimore college students were trained as youth-leaders (YLs) to deliver a skill-based nutrition curriculum to low-income African American children (10-14 years old). In April 2015, formative research was used to inform sustainability of the YL program in recreation centers. In-depth interviews were conducted with recreation center directors (n = 4) and the YLs (n = 16). Two focus groups were conducted with YLs (n = 7) and community youth-advocates (n = 10). Barriers to this program included difficulties with transportation, time constraints, and recruiting youth. Lessons learned indicated that improving trainings and incentives to youth were identified as essential strategies to foster continuity of the youth-led program and capacity building. High school students living close to the centers were identified as potential candidates to lead the program. Based on our findings, the initial intervention will be expanded into a sustainable model for implementation, using a train-the-trainer approach to empower community youth to be change agents of the food environment and role models.Johns Hopkins Urban Health InstituteGlobal Obesity Prevention Center at Johns HopkinsEunice Kennedy Shriver National Institute of Child Health and Human DevelopmentOffice of the Director, National Institutes of Health [U54HD070725]646 CNPq [GDE: 249316/2013-7]Johns Hopkins Bloomberg Sch Publ Hlth, Baltimore, MD USAUniv Tennessee, Knoxville, TN USAUniv Fed Sao Paulo, Santos, SP, BrazilDept Recreat & Pk City Baltimore, Baltimore, MD USAUniv Maryland Extens, Ellicott City, MD USAUniv Fed Sao Paulo, Santos, SP, BrazilWeb of Scienc