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conducted additional live-trapping near the VanVleet parcel on City of
<br /> Boulder Open Space Department lands. Live-trapping was conducted on
<br /> appropriate moist, lowland habitats at Burke I (Section 3, T 1S, R 70W),
<br /> south of Baseline Road, and Burke II (Section 34, T 1N, R 70 W), north
<br /> of Baseline Road, just east of Boulder, Colorado from August 12-15,
<br /> 1992. Over a total of 300 trap-nights on each parcel, no Z. h. preblei
<br /> were captured. No other live-trapping surveys were conducted to
<br /> determine the status of the subspecies in Colorado or Wyoming.
<br /> 8. General ecology-The general ecology of Z. hudsonius is summarized by Quimby(1951),
<br /> Krutzsch (1954) and Whitaker (1972). Specific studies concerning Z. h. preblei in
<br /> Wyoming and Colorado, are very scarce. Observations of intraspecific behavior of Z.
<br /> hudsonius (Jones and Jones 1985) represent the only specific information available for the
<br /> subspecies of concern. As a result,species information is presented in lieu of subspecies
<br /> information.
<br /> A. Food and feeding behavior- Quimby (1951) studied food preferences by
<br /> presenting to caged Z. hudsonius the plants and invertebrate animals normally
<br /> available to these mice in nature. He indicated that, in general, the starchy fruits
<br /> of the Gramineae and the more or less fleshy fruits of various groups of plants
<br /> (Ribes,Fragaria,Rubus,Cornus, Vaccinium, and Vicia)are more heavily utilized
<br /> than other plant materials. The fruits of 15 plants, including Typha, Cyperus,
<br /> Scripus,Salix, Corylus,Alnus, Chenopodlum, Trifolium,Rhus, Cicura, Asclepias,
<br /> Phlox, Plantago, and Rudbeckla, were not eaten. The starchy roots of Typha and
<br /> leaves of Seraria were slightly utilized. Z. hudsonius is also highly insectivorous;
<br /> of 280 insects species, 2 Gastropods, 1 Arachnid, and 1 Diplopod provided, all but
<br /> adult silphid and coccinelid beetles and larval papillionid caterpillars, and the
<br /> highly chitinous pans of insects were consumed. Z. hudsonius is known to
<br /> consume many insects under natural conditions.
<br /> Whitaker(1972) examined the stomach contents of 796 Z. hudsonius, and found
<br /> • that when this species emerges from hibernation in late April and May it feeds
<br /> on a variety of foods. Animal material is about half the food and seeds are about
<br /> 20%. As the season progresses, more seeds and less animal materials are
<br /> consumed, and the fungus Endogone becomes important and is actively sought
<br /> by the animals. Seeds, particularly grass seeds, are the basic food in general.
<br /> The different grasses are used in sequence as they progressively ripen and
<br /> disappear in the field. Some of the more important seeds eaten were those of
<br /> Phleum, Anrhoxanrhum, Poa, Cerasrium, Rumex acetosello, Dactylus, Porenrilla,
<br /> Oxalis, Echinochloa, Ulmus, and Asclepius. The most important of the animal
<br /> foods were lepidopterous larvae and beetles of the families Carabidae and
<br /> Curculionidae.
<br /> Quimby (1951) described a caged mouse feeding on grass seeds. It sat on its
<br /> haunches and fed by means of the front feet. First the fruiting head of the grass
<br /> was cut off, then all parts were stripped beginning at one end. Only the seeds
<br /> were eaten, but many of these dropped to the ground, and no effort was made to
<br /> retrieve them. Whitaker(1972) made similar observations. Zapus reach as high
<br /> as they can on grass stems, or climb stems to bite through the stem to cut off the
<br /> seed head for consumption (Whitaker 1972). These mice apparently forage on
<br /> the surface and in the herbaceous vegetation above the ground, but the fungal
<br /> foods extensively eaten are probably obtained by scratching the ground (Whitaker
<br /> Fhw 9aau Surrey
<br /> Piuroc FLS,Ie<
<br /> March?A.1993 17
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