1997-06-13_REPORT - M1981302 ‎(16)‎

• Permit No: M1981302
• IBM Index Class Name: Report
• Doc Date: 6/13/1997
• Doc Name: EXHIBIT A 12
• Media Type: D
• Archive: No

D)Development
The Front Range area has one of the fastest rates of residential and commercial real estate
development In the United States. Some of this development is located near or adjacent to riparian
areas, and there may be several adverse impacts on the mouse associated with these activities:
• paving/building: Covers land area (including possible habitat), alters area water quality and
quantity. This includes the use of upland areas that may be used as hibemacula.
• housecats/feral cats: Cats may have sizable hunting territories and their effectiveness at hunting
song birds is well know;their effect on small mammal populations is not as well documented.
• human use of riparian areas: Developments we often placed near riparian areas because of
their visual amenities,and the increased foot traffic bicycles,noise,tight,and trails may have
adverse affects.
• use of aggregate materials:The use of sand and gravel for roads and other construction
activities impacts the riparian drainages associated with aggregate sources, but the greater
impact is at the oRsite areas where the construction occurs.
The group is concerned with these impacts because several areas with adequate vegetation
structure for the mouse have been surveyed unsuccessfully in the past year(primarily in Denver
Canty),and many of these sites are located near housing developments.
Ryon(19%)recently trapped the mouth of Left Hand Carryon,a site that had yielded Zapus captures
in 1965(Crtaan 196I1). The site has since been developed and w Zapus were raptured two in
1995.
Q Hang:
As mentioned in Section VI,jumping mice have been found in hay fields on City of Boulder Open
Space. The field in question has a 60/40 ratio of nativehiorvtative grasses,and an irrigation Mch is
nearby. This area had been trapped several times as part of a larger biadrveraily project, and Qua
fact that only a few Zapus have been captured there may Indicate that use of this habitat is
uncommon.
Fields at Rocky Flats that had forrnerty been cultivated and then planted to Bromus(nerrrxs and
Agmpyron wermedium have also been extensively trapped with no Zapus caphae& We do not
know of any Zapus surveys that have been conducted in alfalfa fields,but Zapus presence would
probably not be expected.
Zapus are reported in the literature to use the edges of cultivated fields that are adjacent to tipariart
areas,which is rot unexpected given the wandering nature of this animal
F)Riparian hydrology
The importance of rfpartan habtlat has been noted throughout this report and these areas are
dependent on surface and groundwater sauces. Colorado stream hydrographs have been vastly
altered in the past 100 years,primarily by dams and irrigation related diversions. Knopf at al.(1993)
recognized the creations of different landscapes In the Platte River headwaters due to atered
surface water flows. Urba.Nzatlon also changes the quality and quarrltfy of runoff, and many stream
charnels have been downcut nprapped and eroded as a consequence.
These changes can directly ailed riparian water supplies and late-season flows may be diminished
or Increased,depending on die drainage. The group is especially concerned that alterations in
stteamftow will change the vegetation structure in the riparian zone. Critical woody spades such as
willows and cottonwoods are dependent on reliable surface or groundwater sources,and
maintenance of this woody component Is essential in these drainages. The long term effects of
erosion and siltation on meadow jumping mouse habitat are unknown.
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