Demography of the Meadow Jumping Mouse (Zapus hudsonius) in Eastern Massachusetts

Abstract

The meadow jumping mouse (Zapus hudsonius) was live-trapped for 5 years in eastern Massachusetts. Densities were low throughout the study, with yearly peak numbers ranging from 3.1-7.5 per ha. Female jumping mice reached sexual maturity at a weight heavier than males. Survival rates were low, but this could be attributed largely to a high degree of transiency; once mice achieved residency, loss rates were low. Demographic attributes of this population of Zapus were compared with populations of the meadow vole (Microtus pennsylvanicus) and the white-footed mouse (Peromyscus leucopus) in eastern Massachusetts. The most important differences between Zapus, which hibernates, and the two nonhibernating species were in the life span and survival of residents and the length of the breeding season. We suggest that some demographic classifications of zapodids may have been premature. INTRODUCTION Jumping mice (genus Zapus) are distributed widely in North American grasslands, and many natural history studies have been conducted on several species (Whitaker, 1972). However, few detailed studies on demography have been reported on these hibernating mice. Brown (1970) and Cranford (1983) studied the demography of several populations of Z. princeps in Wyoming and Utah, respectively, and Nichols and Conley (1982) studied a population of Z. hudsonius in Michigan. Further data on demography from Zapus populations are needed for comparison with more widely studied nonhibernating small mammals to determine how the strategies of demography of hibernators and nonhibernators differ. We report here the results of a 51-month study on the demography of a population of Zapus hudsonius in eastern Massachusetts. We compare these results with demographic features of two nonhibernating small mammals, the meadow vole (Microtus pennsylvanicus) and the white-footed mouse (Peromyscus leucopus), inhabiting grasslands in eastern Massachusetts. We are testing the model of French et al. (1975), which suggests that Zapus will show high survival, low reproductive activity and low density compared to the two nonhibernating species. MATERIALS AND METHODS Live trapping was conducted year-round in grassy fields at the Broadmoor/Little Pond Audubon Sanctuary in South Natick, Massachusetts, from August 1978 to October 1982. Data were collected from two 0.8-ha rectangular grids (gridsJ and K) consisting of 100 trap stations each. Trap stations were spaced 7.6 m apart. Grid K was bounded on three sides by a 0.75-m high galvanized steel fence as part of an experimental study of the meadow vole Microtus pennsylvanicus. The fence did not restrict movement of Zapus because individuals trapped on Grid K were often captured outside the fence. Both fields were dominated by bluegrass (Poa pratensis) and goldenrod (Solidago spp.). Eighteen additional trap stations were located 15.2 m from grid J in deciduous woodland. One Ketch-All, multiple-capture live trap was placed at each station. Traps were baited with oats and supplied with cotton for bedding. Trapping was conducted month1 Present address: George S. Wise Faculty of Life Sciences, Department of Zoology, Tel Aviv University, Ramat Aviv, Tel Aviv, Israel.