BOARD02067

• Board Meeting Date: 3/29/1999
• Description: South Platte Director's Report - Preble's Meadow Jumping Mouse Status Report
• Board Meetings - Doc Type: Memo

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In addition, there are movemeot data to suggest some distance from a "source" .
that a moving individual may locate an isolated patch of suitable vegetation.
. Extensive variability is exhibited in the movement data from different populations
with individuals at the U. S. Air Force Academy moving very little (Rob Schorr,
1999, unpublished data) while PMlM from Rocky Flats moved up to one mile in
a single night (Tom Ryon, unpublished data). Other researchers have also
. recorded extensive variability in movement (e.g., Adler et al. 1984; Nichols and
Conley 1982, and others). The Science Team reached consensus that a
minimum patch size within one mile of a source population may be occupied
for at least long periods of tiI1le. .

Shape is likely to have an impact on survival of mice. For example, a 1,000 ft2
area could be...333ft x 3ft, an extent that several Science Teammembe.rs..believed
was excessive if altered along a narrow corridor such as ditches. It is possible that
attributes of non-shrub habitat compensate for the constraints on the minimum
home range size (i.e., a considerable part of the home range may actually be
composed of non-shrub habitat). Therefore, in following with one of the Science
Team's guiding principles, we concluded that a conservative estimate of ditch
length was advisable. .

. Team Recommendations:

1. The minimum patch size of suitable habitat isolated from other such patches . .
should be less than the minimum measured home range size for PMJM--O.25 ac
(O.lha). This is an area of 10,760 ft2 (1,000 m2). [Confidence level = high]
2. Whatever the shape of the patch, it should not be more than 109 ft on a single
side. [Confidence level = med]. .
3. To be considered unsuitable, an isolated patch should be greater than one mile
from a like or larger patch in the same valley floor reach. [Confidence level =
med.] .

Assumptions:

1.

We agreed that an appropriate interpretation would be that a mouse was unlikely
to occupy a patch less than indicated because of insufficient area and/or resources.
We based the analysis only on the probability of a mouse occupying any patch,
including those larger or smaller than the indicated size.
We assumed that any resulting ditch maintenance activity would not significantly
change adjacent land uses (e.g., a new housing development or an added
highway).
We assumed that the habitat alteration would be temporary, i.e., largely restored
after the action [including the normal amount of water delivered downstream ].
We assumed that the work would be done out of season (from Nov to the end of
April), but it should be noted that this should not be pertinent to the minimum
patch size of an isolated patch sioce it is predicted to NOT be occupied.

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