Hilde Karine Wam
Research Professor
Authors
Robert Spitzer Monica Ericson Annika M. Felton Morten Heim David Raubenheimer Erling Johan Solberg Hilde Karine Wam Christer Moe RolandsenAbstract
Understanding how the nutritional properties of food resources drive foraging choices is important for the management and conservation of wildlife populations. For moose (Alces alces), recent experimental and observational studies during the winter have shown macronutrient balancing between available protein (AP) and highly metabolizable macronutrients (total non-structural carbohydrates [TNC] and lipids). Here, we combined the use of continuous-recording camera collars with plant nutrient analyses and forage availability measurements to obtain a detailed insight into the food and nutritional choices of three wild moose in Norway over a 5-day period in summer. We found that moose derived their macronutrient energy primarily from carbohydrates (74.2%), followed by protein (13.1%), and lipids (12.7%). Diets were dominated by deciduous tree browse (71%). Willows (Salix spp.) were selected for and constituted 51% of the average diet. Moose consumed 25 different food items during the study period of which 9 comprised 95% of the diet. Moose tightly regulated their intake of protein to highly metabolizable macronutrients (AP:TNC + lipids) to a ratio of 1:2.7 (0.37 ± 0.002SD). They did this by feeding on foods that most closely matched the target macronutrient ratio such as Salix spp., or by combining nutritionally imbalanced foods (complementary feeding) in a non-random manner that minimized deviations from the intake target. The observed patterns of macronutrient balancing aligned well with the findings of winter studies. Differential feeding on nutritionally balanced downy birch (Betula pubescens) leaves versus imbalanced twigs+leaves across moose individuals indicated that macronutrient balancing may occur on as fine a scale as foraging bites on a single plant species. Utilized forages generally met the suggested requirement thresholds for the minerals calcium, phosphorus, copper, molybdenum, and magnesium but tended to be low in sodium. Our findings offer new insights into the foraging behavior of a model species in ungulate nutritional ecology and contribute to informed decision-making in wildlife and forest management.
Authors
Annika M. Felton Hilde Karine Wam Zbigniew Borowski Aksel Granhus Laura Juvany Juho Matala Markus Melin Märtha Wallgren Anders MårellAbstract
Climate change causes far-reaching disruption in nature, where tolerance thresholds already have been exceeded for some plants and animals. In the short term, deer may respond to climate through individual physiological and behavioral responses. Over time, individual responses can aggregate to the population level and ultimately lead to evolutionary adaptations. We systematically reviewed the literature (published 2000–2022) to summarize the effect of temperature, rainfall, snow, combined measures (e.g., the North Atlantic Oscillation), and extreme events, on deer species inhabiting boreal and temperate forests in terms of their physiology, spatial use, and population dynamics. We targeted deer species that inhabit relevant biomes in North America, Europe, and Asia: moose, roe deer, wapiti, red deer, sika deer, fallow deer, white-tailed deer, mule deer, caribou, and reindeer. Our review (218 papers) shows that many deer populations will likely benefit in part from warmer winters, but hotter and drier summers may exceed their physiological tolerances. We found support for deer expressing both morphological, physiological, and behavioral plasticity in response to climate variability. For example, some deer species can limit the effects of harsh weather conditions by modifying habitat use and daily activity patterns, while the physiological responses of female deer can lead to long-lasting effects on population dynamics. We identified 20 patterns, among which some illustrate antagonistic pathways, suggesting that detrimental effects will cancel out some of the benefits of climate change. Our findings highlight the influence of local variables (e.g., population density and predation) on how deer will respond to climatic conditions. We identified several knowledge gaps, such as studies regarding the potential impact on these animals of extreme weather events, snow type, and wetter autumns. The patterns we have identified in this literature review should help managers understand how populations of deer may be affected by regionally projected futures regarding temperature, rainfall, and snow.
Authors
Annika M. Felton Hilde Karine Wam Zbigniew Borowski Aksel Granhus Laura Juvany Canovas Juho Matala Markus Melin Märtha Wallgren Anders MårellAbstract
Climate change causes far-reaching disruption in nature, where tolerance thresholds already have been exceeded for some plants and animals. In the short-term, deer may respond to climate through individual physiological and behavioral responses. Over time, individual responses can aggregate to the population level and ultimately lead to evolutionary adaptations. Because responses by deer to climate change may take many paths - both positive and negative - it is generally difficult to predict outcomes. Here we take the first step to understanding these complexities by systematically synthesizing the literature (published 2000-2022) regarding direct effects of temperature, rainfall and snow on deer inhabiting boreal and temperate regions of the northern hemisphere. Our review (based on N= 219 papers) shows that while many deer populations will likely benefit from warmer winters, hotter and drier summers may exceed their physiological tolerances, causing northwards shifts in distributional ranges. We found support for deer expressing both phenotypic and behavioral plasticity in response to climate variability at different temporal and spatial scales. We identified 20 general patterns, among which some illustrate antagonistic pathways, suggesting that detrimental effects will cancel out some of the benefits of climate change. Our findings highlight the importance of local variables for any predictions of future responses by a given deer population. We identified several knowledge gaps, such as studies regarding the potential impact on these animals of extreme weather events, snow type and wetter autumns.