Camp. Biochem. Pf>ysioi. Vol. 109A, No. 3, pp. 601-610. 1994 Copyright c, 1994 Elsevier Science Ltd Printed in Great Britain. All rights reserved 03~-96~9/94 $7.00 + 0.00 Proximate, caloric, nitrogen and mineral composition of bodies of some tropical bats Eugene H. Studier, * Steven H. Sevick* and Don E. Wilson? *Department of Biology, University of Michigan-Flint, Flint, MI 48502-2186, U.S.A.; and ~National Museum of Natural History, Smithsonian rnstitution, Washington, D.C. 20.560, U.S.A. Proximate (live mass, water, lipid, ash, non-fat organic), caloric, nitrogen, and mineral (sodium, potassium, calcium, magnesium, and iron) concentrations and total body content of individuals of 24 species of Neotropical and Paleotropical bats were determined. Mass-related, concentration patterns were found for all measured variables, except iron. Concentrations increase with size for nitrogen, calcium, and magnesium but are concave, opening upward, for sodium and potassium. These last two elements reach minimal concentrations in bats weighing about 22 and 28 g dry mass, respectively. Total body content of nitrogen and minerals was compared with amounts in similar-sized birds and tetrapodal mammals* Key words: Bat; Bird; Mammal; Body composition; Nitrogen; Sodium; Potassium; Calcium; Magnesium; Iron. zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDC Comp. Biochem. Physiol. 109A, 601-610, 1994. zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLK Introduction Studies of body composition of tropical and temperate bats have been limited mainly to variables such as caloric content and lipid levels, which are related to energetics (McNab, 1976). Similar emphases have been applied to other small mammals (Studier, 1979) and birds (Holmes, 1976). That trend relates directly to the implied critical importance of energetics as a prob- able limiting factor in maintaining adequate nutritional budgets in small endotherms. Recent investigations in birds (Hungerford ef al., 1993), other small mammals (Randolph et af., 1991; Willig and Lather, 1991), and bats (Studier and Kunz, 1994) Correspondence to: E. H. Studier, Department of Biology, University of Michigan-Flint, Flint, MI 48502-2186, U.S.A. Tel. 810 762 3360. Received 31 January 1994; accepted 10 June 1994. have expanded studies of nutrition to include nitrogen and mineral requirements and budgets. Iust as body energy concen- tration (Cummins and Wuycheck, 1971) is essential in the calculation of energy budgets, similar estimates of nitrogen and mineral levels are necessary to establish budgets for. those nutrients. Limited data are available on nitrogen and mineral concentration and content in small birds (Bilby and Widdowson, 1971; Sturges et al., 1974; Hagen et al., 1976; Pinowski et al., 1983; Taylor and Konarzewski, 1992) and other mammafs (Gentry ef at., 1975); how- ever, no data have been published on levels of those elements in bats. We present data on live mass, water, fat, and non-fat organic matter, as well as on nitrogen, sodium, potassium, calcium, magnesium and total iron levels in a broad sample of tropical bat 601