1997-06-13_REPORT - M1981302 (16)

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7. U.S.Air Force Academy, El Paso County. Extensive trapping efforts during 190 and 19N have yielded meadow jumping mice in a number of different habitat types in Monument Creek and its tributaries on the Academy. In addition, mice were captured on Smith Creek east of the Academy, Smith Creek is also a tributary of Monument Creek. Pending further investigations, these seven populations can be viewed as forming four core areas and an isolated population: Warren Air Force Base i.. Wyoming;South Boulder Creek-Rock Creek drainages,which include Coal Creek in-between them and Walnut Creek and Woman Creek to the south of Rock Creek;the Plum Creek drainage,which includes West Plum Creek East Plum Creek and Indian Creek; and the Monument Creek drainage,which inch s Smith Creek and other tributaries of Monument Creek: and the shingle site along St Vrain Creek at Hygiene. Additional populations of meadow jumping mice may be undiscovered. However,given that the appropriate habitats in Colorado mostly are private lands subject to rapid development(Including residential,commercial, and industrial uses,especially gravel-rrw*g), it is likely that some undiscovered sites have been or will be destroyed Certainly,marry of the historic sites have been lost and the fact that no meadow jumping mice were captured at any of these sites in a recent survey supports the suggestion that this species has suffered a decline within its historic range in Colorado(Ryon 1996). IL Small Mammal Community Ecology Table 1 indicates assemblages of small mammals sampled in a number of habitats Wong the Colorado Piedmont in the past several years. The table Includes small mar riuds from both his0orical sites of capture(e.g.. Ryon, 1998)and other sites with habitat apparently suitable for fm meadow jumping rr o . Trapping effort varied from one study to another so all data are reported here as percentages of total captures. In akkfrtion to the studies tabulated, three caphires of two meadowFtmping mice were captured 20 and 21 August 1996, at the.Ranson/Edwards Homestead Ranch,which is SW of Rocky Flak and just north of OPlainview,'Colorado Highway 7Z Coal Creek SW 1/4 sec,8,T 2.S, R 70 W(Fleming of al., 1996). Species taken in the same transects were Aeromyscus msnr aul3fu% Adaotus perntsykw=s, M fongiiceuduA M. ochmgas<er, Mus mu=dus, 'Sigmodon hapdus" (=OWetodp vs hispidus?)and Meoloim mexicana Numbers of captures of these associated species were not provided, so this information could not be irtduded in the table. These data indicate that on sites where the jumping mace has been captured,capture rates range from 0.5 to 300A of the total catch. On most sites,the caphxe rate is<5%. it is dear that where the meadow,jumping mouse has been food in Colorado,A is usually a rare spades in the smug mammal community. UL Hibemation/Active Period Lille is known of hibembon and active period relatorships d the mouse life cycle. M do have gritted but incomplete l dormetlon on fie active period,but much less is known on hibematort dynamics. Most studies trove been conducted during high activity sunwner periods and neglect times of emeigertceilimmergence. Based on the earliest emergence and Wiest Immergence dates from Colorado, mice may hibernate for up to 189 days. There is probady kiss variance in dates of emergence than immergence, partially because all mice OW emerge are adults Two stages of immergence were found in extenshe 1995 sfudes at Rocky Flats,accodung to age class. Adults were not captured after September 8.and recaptured animals were observed to gain weight in the 2 to 3 week period prior to disappearance. In other Rocky Fiats studies,no adult mice have been captured after September 8 either. In the 1995 study,juvenilelsubadut mice were 4