Meet the Real Mighty Mouse: The Preble’s Meadow Jumping Mouse


Mion Mighty Mouse

Published in Sept. Oct 2017 issue of The Redstone Review.


The Preble’s Meadow Jumping Mouse, a.k.a. PMJM, was first discovered in Colorado by Edward A. Preble a century before it was listed under the Endangered Species Act in 1998 and locally, Boulder County Commissioners approved Special Use Permit 96-18 to convert up to 640 acres of the St Vrain Valley’s Agricultural land and riparian habitat to the industrial use of gravel mining.

Fast forward almost two decades later, SU 96-18 comes out of its hibernation silently and in the dead of winter in January 2017 when the current Boulder County Commissioners approved Martin Marietta Material’s building site plans on it’s five acre property in Lyons, off HYW 66. The illusive Preble’s Meadow Jumping Mouse is still endangered but thriving in the St Vrain Valley and the entire South Branch ditch pre and post 2013 floods.

Besides its endearing name that may conjure images of wildflowers, the soothing sound of a flowing stream and the kind shade of lush trees and shrub clusters, that is if you’re fortunate enough to spend time in such places and experience the Peace of Wild Things; PMJM’s arguably cute physicality and resemblance to Terrytoons‘ Mighty Mouse with its extremely long tail (that accounts for more than 60 percent of its 8-10 inches length), disproportionately big hind feet and legs designed to help it swiftly leap across small creeks, through wetlands, dense grasses and shrubs in specific riparian habitat where it dwells; They hibernate up to 9 months from September or October through May, according to US Fish & Wildlife. PMJM historically has the super power of staving off indiscriminate industrial takeover in the Front Range– a mighty feat as the urban edge gets blurred by all the industrial smog that can’t be glossed over by all the green-washing, double speak.

Eric Lane, Director of Boudler County Parks & Open Space, (BCPOS) in a recent email to US Fish & Wildlife dated June 27th, says that “Of particular value and concern to…[BCPOS] is habitat of Preble’s Meadow Jumping Mouse present in the project area. This project area contains invaluable habitat for the mouse, and [BCPOS] trapping studies over the past three years have shown that its comparative importance in the broader landscape context is highly significant”. Using PIT tagging, BCPOS documented 154 unique individual mice in the St. Vrain corridor and the South Branch of the St. Vrain. In comparison, trapping within federally designated critical habitat for the mouse in Boulder County, South Boulder Creek, resulted in very few individuals, and *no trapping success within the Rocky Flats Wildlife Refuge. BCPOS director affirms “…that *the population along the St. Vrain is of increasing importance in a population dynamic context. [And] While [BCPOS]…[has] reviewed the 2001 Biological Opinion (ES/GJ-6-CO-01-F-045) associated with this project, some of the mitigation measures are difficult to interpret sixteen years later…on the ground *conditions have changed with the passage of time, implementation of some measures by the operator, changes in the ownership and the proposed mining footprint, and lasting effects of the 2013 flood such that a review of the 2001 Biological Opinion by USFWS as part of the overall permit review process is also warranted.”

Habitat Conservation Plans serve a higher purpose than preserving the PMJM; their habitat protection positively affect water quality and quantity; plants act like a buffer zone and filtration system for both surface runoff and water flowing into streams through groundwater or subsurface flow and lower nitrate contamination in surface runoff from fertilizers and manure that would compromise human health and the ecosystem. Riparian zones distribute the streams flow with its root system and diverse plant community, slowing the water, reducing flooding and soil erosion. The St Vrain Valley has had floods for thousands of years. In the 2013 floods, previously mined ponds ruptured and caused severe flooding even in Hygiene and non-floodplain areas of Longmont. There will be more floods in this valley and riparian habitat is needed to protect residents and wildlife, not more mined ponds leading to future flood-damage.

Approximately 90 percent of all wildlife species rely on stream habitats for survival. The conservation of these limited resources is critically important for the survival of many wildlife species. Robertson, of the Center for Native Ecosystems, calls the stream corridors of the Front Range “a network of blood vessels in the landscape,” and “magnets for biodiversity.” With the uncertain future of water resources in the west, wetland habitat in the St Vrain Valley needs to be conserved. Destruction of the most biologically diverse habitats on the Front Range is arguably unrecoverable. As evidenced in the comparison of live PMJM captures: Rocky Flats 0 vs. 145 captures in the St Vrain and South Ditch, the habitat once damaged by irresponsible industry does not recover readily and is never enhanced–it seems that the PMJM don’t thrive in an open space “complex” and require the natural, undamaged, undisturbed habitat of the St. Vrain Valley. There are not many areas left for them but there are plenty of open space complexes.

Jacob Smith, the executive director of the Center for Native Ecosystems in 2004 stated “We’re talking about housing developments and gravel mines here, [The Front Range] is getting blitzed. It’s just getting completely devastated. Protecting the Preble’s mouse is a core part of protecting what’s left of the Front Range.”

Please write your letters to US Fish & Wildlife and ask that the 2001 Biological Opinion (ES/GJ-6-CO-01-F-045) associated with this project be reassessed, and a current Biological Opinion be done. Ask for maximum protection for the PMJM and the Hygiene Bald Eagles from Martin Marietta Material’s proposed mining.

Amanda Dumenigo, Chairperson, SOSVV

Additional Resources:

SOSVV website

BCCP Environmental Conservation Areas Map

BCCP Preble’s Meadow Jumping Mouse Conservation Areas Map

BCCP Wetlands & Riparian Areas MapBest Management Practices for Wildlife Corridors

Survey of Critical Biological Resources in Boulder County, Colorado 2007-2008

“Mighty mouse: How the Prebles meadow jumping mouse has stood up to Front Range development, and why it is losing” By Benjamin Glahn for Colorado Springs Independent, 2004.

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