1997-06-13_REPORT - M1981302 (15)

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The animals are deep hibemators, remaining down from about October to April or early May in New York (Whitaker, 1963). Most breeding seems to occur between early June and mid-August (Whitaker, 1972). Females are polyestrous and have two or three litters of two to eight (average four or five) young per year, with a gestation period of 17 to 21 days (or longer for lactating females). Quimby (1951) and Whitaker (1963) published the most thorough studies of the species to date, emphasizing autecology (including reproduction and annual cycles). Whitaker (1972) reviewed the literature on the meadow jumping mouse. The population of Zapus hudsonius in Colorado and adjacent southeastern Wyoming was recognized as a distinct subspecies, Z. h. preblei, by Krutzsch (1954), with a type locality at Loveland, Larimer Co., Colorado. The population appears to be geographically isolated from populations to the north (Z h. campestris in northeastern Wyoming) and east (Z h. pal/ldus in eastern Kansas and eastern and central Nebraska). Meadow jumping mice have not been captured in Colorado east of Greeley, despite a fair amount of research on small mammals along the South Platte River (at Tamarack Ranch in Logan County, for example—see Fitzgerald, 1978, and Sampson et al., 1988), nor have they been captured south of Colorado Springs. Coloradan populations of meadow jumping mice apparently are isolated from those to the south in New Mexico (Z. h. luteus—see Hafner et al., 1981). Armstrong (1972:360) noted the peculiar continental distribution of Z hudsonius, and suggested that it was— like members of the so-called "Boren-Cordilleran faunal element'—a species relict in Colorado, isolated by warming and drying in Holocene times. The first reference in the scientific literature to jumping mice in Colorado was by Baird (1858:433) who listed a specimen of"Jaculus hudsonius" from "R. Mountains, 38' par." This specimen was obtained by the Gunnison Expedition and is the species now known as Zapus princeps, the western jumping mouse (a species not recognized until named by Allen (1893). Much of the history of knowledge of the meadow jumping mouse in Colorado is based on work in Boulder County. Coues (in Dartt, 1879; republished in Benson, 1986) listed Zapus hudsonius among the specimens in Martha Maxwell's natural history collection, as exhibited at the 1876 Centennial Exposition in Philadelphia. Warren (1911:320) noted correctly that this specimen could have been either the western jumping mouse or the meadow jumping mouse. For one thing, when Coues compiled his list of the Maxwell Collection, the western jumping mouse had not yet been recognized as a distinct species. Secondly, Maxwell collected widely in the vicinity of Boulder, "on the plains and among the peaks," and therefore she could have encountered both species of jumping mice in Boulder County. Maxwell's collection was dispersed and much of it apparently has been lost. The fate of her specimen of a jumping mouse is unknown. Preble (1899) was the first to report Zapus hudsonius—unequivocally and as currently understood—from Colorado, listing specimens from Loveland as examined. Cary 2