196 Journal of Mammalogy, 103(1):196–208, 2022 https://doi.org/10.1093/jmammal/gyab130 Published online November 26, 2021 © The Author(s) 2021. Published by Oxford University Press on behalf of the American Society of Mammalogists, www.mammalogy.org. Individual snowshoe hares manage risk differently: integrating stoichiometric distribution models and foraging ecology Isabella C. Richmond,* , Juliana Balluffi-Fry, Eric Vander Wal, Shawn J. Leroux, Matteo Rizzuto, Travis R. Heckford, Joanie L. Kennah, Gabrielle R. Riefesel, and Yolanda F. Wiersma 1 Department of Biology, Memorial University of Newfoundland, 232 Elizabeth Avenue, St. John’s, NL A1B 3X9, Canada *To whom correspondence should be addressed: icrichmond@mun.ca Herbivores making space use decisions must consider the trade-off between perceived predation risk and forage quality. Herbivores, specifcally snowshoe hares (Lepus americanus), must constantly navigate landscapes that vary in predation risk and food quality, providing researchers with the opportunity to explore the factors that govern their foraging decisions. Herein, we tested predictions that intersect the risk allocation hypothesis (RAH) and optimal foraging theory (OFT) in a spatially explicit ecological stoichiometry framework to assess the trade- off between predation risk and forage quality. We used individual and population estimates of snowshoe hare (n = 29) space use derived from biotelemetry across three summers. We evaluated resource forage quality for lowbush blueberry (Vaccinium angustifolium), a common and readily available forage species within our system, using carbon:nitrogen and carbon:phosphorus ratios. We used habitat complexity to proxy perceived predation risk. We analyzed how forage quality of blueberry, perceived predation risk, and their interaction impact the intensity of herbivore space use. We used generalized mixed effects models, structured to enable us to make inferences at the population and individual home range level. We did not fnd support for RAH and OFT. However, variation in the individual-level reactions norms in our models showed that individual hares have unique responses to forage quality and perceived predation risk. Our fnding of individual-level responses indicates that there is fne-scale decision-making by hares, although we did not identify the mechanism. Our approach illustrates spatially explicit empirical support for individual behavioral responses to the food quality–predation risk trade-off. Key words: autocorrelated kernel density estimation, Bayesian, boreal forest, ecological stoichiometry, habitat complexity, individual responses, optimal foraging theory, perceived predation risk, risk allocation hypothesis, trade-offs Animals make trade-offs that shape ecosystems, and one of the most ecologically relevant trade-offs made by herbivores is the balance between foraging and predator avoidance (Lima and Dill 1990; Verdolin 2006). Herbivores should optimize their space use to obtain food with suffcient levels of nutrients to survive (Charnov 1976; Bjørneraas et al. 2012) and minimize predation risk (Lima and Bednekoff 1999; Graham and Nash 2013; Liu et al. 2014). Often, the parts of the landscape that provide enough nutrients to herbivores do not provide suffcient safety, forcing a balance in space use (Lima and Dill 1990; Wilson et al. 2012). Space use decisions by herbivores can alter the surrounding ecosystem, through processes such as nutrient cycling and plant growth rates (Molvar et al. 1993; Moorhead et al. 2017). Ecological stoichiometric approaches can be useful in testing relationships between space use and food quality be- cause all herbivores have life-history requirements that rely on the access and consumption of elements (Sterner and Elser 2002; Leroux et al. 2020). Herbivores also require and seek out safety, which can be provided by vegetatively complex habitats (Litvaitis et al. 1985). Here, we investigate the spatially explicit relationship between food quality and perceived predation risk using ecological stoichiometry and habitat complexity. Plant stoichiometry, and more broadly ecological stoichi- ometry, refers to the measure of elemental ratios and their balance within living organisms (Sterner and Elser 2002). For herbivores, studies have shown that carbon:nitrogen and carbon:phosphorus ratios of forage (hereafter C:N and C:P) are most important because they control individual body growth rates, defense abilities, and affect developing fetuses (Meunier et al. 2017). For example, moose (Alces alces) that consumed more nitrogen during summer feeding had higher reproductive productivity and increased lean body mass when Downloaded from https://academic.oup.com/jmammal/article/103/1/196/6441781 by guest on 11 May 2023