1997-06-13_REPORT - M1981302 (18)

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1972). Mice in captivity regularly drink water, but it is not known whetherZapus in the field drink or get their water from green vegetation or from dew, or both (Quimby 1951). B. Home range- Quimby (1951) found that the home range of female Z. hudsonius varied from 0.19 to 0.87 acres, with a mean of 0.38 acres, while male home ranges varied from 0.14 to 1.10 acres, with a mean of 0.43 acres, in one area in Minnesota. In another area of Minnesota, he found that nine males had significantly larger home ranges (2.70 acres) than did 17 females (average 1.57 t 0.22 acres). Calculated home ranges in Michigan were 0,89 t 0.11 for 26 males, and 0.92 t 0.11 for 24 females, the differences being not significant (Whitaker 1972). Quimby (1951) theorized that environment plays a major role in determining the size, and that the shape of home ranges is determined by terrain, density and type of cover, and land use in the immediate area. Home ranges shift; in one case an adult moved more than half a mile. Authors have reported the tendency for Z. hudsonius to wander, possibly to seek moist locations during the dry part of summer (Whitaker 1972). Quimby(1951) found them to have essentially no homing tendencies on the basis of releases of 13 individuals 0.2 to 0.5 miles from their original home ranges. Only two returned by chance wandering. C. Population Density- Quimby (1951) estimated that there were 11.91 mice per acre in one Minnesota study area, and gave monthly averages ranging from 1.81 to 3.57 mice per acre for a second area. Authors agree that the population density of jumping mice may vary considerably from year to year(Whitaker 1972). An inverse relationship may exist between Z. hudsonius and meadow vole (Microtus pennsyivanicus) densities because both species have nearly identical distributions over North America and both live in moist meadow habitats (Boonstra and Hoyle 1986). D. Population Structure- Quimby (1951) recognized three age classes, namely adults, subaduls (with adult pelage but of small size), and juveniles (very small • size and juvenile pelage), in a Minnesota Z. hudsonius population. No young of the year appeared in the catch until July when 25% were either juveniles or subaduits. Fifty percent of those caught in August were young of the year. The figures for September were more difficult to determine since the young from early litters have all the appearances of adults at this time; but 61% were definitely young of the year, 8% were definitely adults, the remaining 30% were classified as adults, but some or all were young of the year. These data indicate that the over-wintering adults are gradually replaced by the young of the year as the summer progresses. Factors doubtless include mortality from predation, old age, and other natural causes. Kmtzsch (1954) concluded that sexes in Z. hudsonius vary only slightly from a one to one ratio. E. Predators-Zapus have been reported to be preyed upon by barn owls, mink, and rattlesnake (Quimby 1951, Krutzsch 1954, Whitaker 1972). Z. hudsonius have been reported to be preyed upon by barn and long-eared owls, red tailed hawks, northern pike, weasel, and a green frog (Quimby 1951, Krutzsch 1954, Whitaker 1972). It seems safe to assume that jumping mice are preyed upon by representatives of all major vertebrate groups (Quimby 1951). F. Parasites- Whitaker (1972) provides an excellent summary of the parasites, or associates, of Z. hudsonius. The species harbors few parasites in comparison to many other species of small mammals of comparable size. Among bacteria, FmY O.n,.SL y Pimp FLS,L=