The Efficiency of Food Utilization and Energy Requirements of Captive Female Fishers

Abstract

Sixteen complete digestibility, energy and nitrogen balance trials were carried out to determine the nutritive value of 4 diets fed to 4 captive female fishers (Martes pennanti). Diets consisting of snowshoe hares (Lepus americanus), white-tailed deer (Odocoileus virginianus), small mammals (Microtus pennsylvanicus, Blarina brevicauda, and Peromyscus leucopus or maniculatus), and coturnix quails (Coturnix coturnix) were fed separately in 4 series (time periods) to the experimental animals. Gross energy of diets generally was related positively to ether extract (fats) and negatively to ash percentages in diet dry matter. Dry matter intake per kilogram body weighto075 did not differ significantly (P < 0.05) among treatments. Gross energy intake per kgWo.75 was higher (P < 0.05) on diets of deer and quails. Digestible, metabolizable, and net energy values per gram of dry matter intake were higher (P < 0.05) for deer (5.98, 5.54, 4.30 kcal/g) and quails (6.12, 5.86, 5.27) than for hares (4.32, 3.64, 2.57) and small mammals (4.15, 3.80, 2.69). Efficiency of conversion of dietary nitrogen to body tissue was significantly greater on the hare ration. J. WILDL. MANAGE. 42(4):811-821 The existence of the fisher in New Hampshire is threatened by the destruction of habitat due to development of open and wild lands and overtrapping. The success of restocking efforts, and the accurate assessment of the impact of fishers on game species require better understanding of the many aspects of predation. Studies of the fisher's status and distribution (Hagmeier 1956, Coulter 1960, Dodds and Martell 1971), reproductive potential (Eadie and Hamilton 1958, Wright and Coulter 1967), and food habits (DeVos 1951, Hamilton and Cook 1955, Stevens unpublished data) have contributed to understanding the fisher. However, part of understanding its relationships with prey requires determinations of this carnivore's energy requirements and the nutritive worth of its food, particularly those ingested in winter. This information will help to determine the minimum amounts of prey needed to sustain fishers and to evaluate the relative importance of different prey to fishers. There are numerous reports of feeding trials which dealt with the digestibility, and relative value of commerical feeds for ranch minks (Mustela vison) and foxes (Vulpes spp.) (Bezeau 1950, Inman and Smith 1941, Leoschke 1959, Roberts and Kirk 1964, Seier et al. 1970, Smith 1942). The digestible energy and protein requirements of these ranch animals were also studied (Farrell and Wood 1968b, Harris et al. 1951, Kosko 1968, Kumeno et al. 1970). However, there have been no nutritional studies with fishers and relatively few with other wild carnivores which were fed their natural foods or approximations of such foods (Golley 1960, Golley et al. 1965, Jense 1968, Underwood 1971, Vogtsberger and Barrett 1973). While there have been no determinations of the energy expenditure of fishers, there are reports of the basal and resting metabolic rates of a number of mustelids and other carnivores (Perel'dik ' Published with the approval of the Director of the New Hampshire Agricultural Experiment Station as Scientific Contribution No. 155. 2 Present address: Department of Wildlife Science, Utah State University, Logan 84322. J. Wildl. Manage. 42(4):1978 811 This content downloaded from 207.46.13.83 on Fri, 13 May 2016 07:26:51 UTC All use subject to http://about.jstor.org/terms 812 FISHER ENERGY AND FOOD EFFICIENCY* Davison et al. and Titova 1950, Scholander et al. 1950, Farrell and Wood 1968a, Underwood 1971, Brown and Lasiewski 1972, Iversen 1972). The objectives of this investigation were to evaluate the relative nutritive value for the fisher of 4 diets (snowshoe hares, white-tailed deer meat and viscera, small mammals [meadow voles, short-tailed shrews, white-footed mice], and coturnix quail), and to estimate the fisher's energy requirements for