“…Body composition, and particularly the level of body fat stores, can serve as an index of how well animals respond to variation in the quality of the local environment (Gales et al 1994), can indicate the nutritional status of individuals and populations (Hilderbrand et al 1998;Hundertmark and Schwartz 2002), can provide information about energy and material flux rates (Reilly and Fedak 1990), and can indicate the physical condition, prospects for survival or reproduction, or quality of habitat of an animal (Hwang et al 2005). The role of fat stores in northern species is of particular importance because many animals occurring in cold climates experience seasonal cycles of fat acquisition and depletion associated with limited food availability (e.g., yellow-bellied marmots, Marmota flaviventris (Audubon and Bachman, 1841), Armitage et al 1976; muskrats, Ondatra zibethicus (L., 1766), Virgl and Messier 1992; seals, Phoca groenlandica Erxleben, 1777 (= Pagophilus groenlandicus (Erxleben, 1777)) and Phoca hispida Schreber, 1775 (= Pusa hispida (Schreber, 1775)), Gales et al 1994; porcupines, Erethizon dorsatum (L., 1758), Berteaux et al 2005; skunks, Mephitis mephitis (Schreber, 1776), Hwang et al 2005; raccoons, Procyon lotor (L., 1758), Pitt et al 2006; also see Pond 1978 andWunder 1984).…”