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Hibernation in the Western Jumping Mouse (Zapus princeps)

Jack A. Cranford
DOI: http://dx.doi.org/10.2307/1380226 496-509 First published online: 21 August 1978

Abstract

Seasonal activity, fat deposition, and the hibernation cycle of the western jumping mouse (Zapus princeps) were studied at 2,900 m, 2,500 m, and 2,010 m elevation in the Wasatch National Forest, Utah. Laboratory groups established from all three sites were studied for fat deposition and weight gain with respect to diets, photoperiod, and temperature. The hibernation cycle, occurrence of arousals, weight and fat loss were studied in the laboratory and related to field parameters. The hiber-nacula of 26 animals were found at a mean depth of 59 cm. They contained no cached food reserves. The mean soil temperature throughout the hibernation period was 4.6°C. Emergence of Zapus princeps from hibernation is cued by increasing soil temperature. All field and laboratory populations emerged from hibernation when the temperature of the hibernaculum was between 8.0° and 9.5°C. Animals entered hibernation with 55 to 70% of dry body weight in fat. Weight increased prior to hibernation at an average rate of 0.65 g/day with a maximum of 2.1 g/day. Animals hibernating in the laboratory and in the field lost weight at an average rate of 0.07 g/day. Experiments showed that neither photoperiod nor temperature acts to cue fat deposition. The critical factor for fat deposition is the availability of seeds in the diet.