Rocky Mountain Arsenal National Wildlife Refuge Habitat Management Plan

167 Pages·2013·6.7 MB·English

U.S. Fish & Wildlife Service
Rocky Mountain Arsenal

National Wildlife Refuge
Habitat Management Plan

1
The mission of the U.S. Fish and Wildlife Service is working with others to
conserve, protect, and enhance fish, wildlife, plants, and their habitats for
the continuing benefit of the American people.

The mission of the National Wildlife Refuge System is to administer a
national network of lands and waters for the conservation, management,
and, where appropriate, restoration of the fish, wildlife, and plant resources
and their habitats within the United States for the benefit of present and
future generations.

CITATION: U.S. Fish and Wildlife Service. 2013. Habitat Management Plan : Rocky Mountain Arsenal National
Wildlife Refuge. Commerce City, Colorado: U.S. Department of the Interior, Fish and Wildlife Service, Rocky

Mountain Arsenal National Wildlife Refuge. vi., 157 p.
i
Habitat Management Plan
Rocky Mountain Arsenal National Wildlife Refuge

Submitted by Concurred with by

_/s/ David Lucas July 12, 2013_ _/s/ Wayne King July 30, 2013_
David Lucas Date Wayne King Date
Project Leader Chief, Division of Biological Resources
Rocky Mountain Arsenal National Wildlife Refuge U.S. Fish and Wildlife Service
Commerce City, Colorado Lakewood, Colorado

_/s/ Barbara Boyle August 1, 2013_
Barbara Boyle Date
Refuge Supervisor, Region 6
U.S. Fish and Wildlife Service, Region 6
Lakewood, Colorado

Approved by

_/s/ Will Meeks August 15, 2013_
Will Meeks Date
Assitant Regional Director
U.S. Fish and Wildlife Service, Region 6
Lakewood, Colorado
i
ii
Executive Summary

Located approximately ten miles from downtown Denver, the land (15,988 acres) within the acquisition boundary of Rocky
Mountain Arsenal National Wildlife Refuge (RMANWR) has a well-documented history of significant environmental
disturbance and contamination. The primary causes of degradation were the manufacture of chemical weapons by the U.S.
Army from the World War II through Vietnam eras and the production of pesticides by Shell Chemical Company in the
1980’s. Given the extent and type of degradation, the Environmental Protection Agency (EPA) identified the need for these
lands to be remediated in accordance with the Comprehensive Environmental Response, Compensation, and Liability Act of
1980 (CERCLA, also commonly known as Superfund) to ensure standards for human health and the environment are met
prior to transferring ownership to the National Wildlife Refuge System (NWRS) for management as a National Wildlife
Refuge. Remediation activities mandated under CERCLA will result in restoring approximately 67% (10,739 acres) of
RMANWR lands to native short- and mixed-grass prairie. Other habitats that will be present on RMANWR include
shrublands, forested lands, riparian areas, and numerous manmade features (irrigation lakes, ditches, homesteads, etc.), many
of which are of cultural or historic importance.

The Habitat Management Plan (HMP) is a “step-down” plan from the RMANWR Comprehensive Management Plan (CMP)
completed in 1996. Guidance for developing an HMP is based on relevant Service laws and policies, including the
RMANWR Act of 1992 (PL 102-402), the National Wildlife Refuge System Improvement Act of 1997 (Improvement Act),
and the Service policy on Biological Integrity, Diversity, and Environmental Health (BIDEH) (U.S. Fish and Wildlife Service
2001). The RMANWR Act stipulates eight purposes for establishment of the Refuge, the Improvement Act mandates the
environmental health of refuge lands be evaluated and analyzed to “ensure that biological integrity, diversity, and health of
the System are maintained for the benefit of present and future generations of Americans”, and BIDEH directs managers to
employ management that “restores or mimics natural ecosystem processes or functions to achieve Refuge purposes.”
Collectively, these and other documents stipulate that refuge managers should implement the most appropriate management
actions to restore degraded systems to the extent possible and prevent further degradation of systems, which will depend on
many factors including funding and staffing.

Significant restoration of RMANWR habitats has occurred since completion of the CMP and, in addition, a new
Comprehensive Conservation Plan (CCP) will be developed beginning in 2013 to replace the CMP. Although the goals and
principles outlined in the CMP are used to the extent possible, many habitat management recommendations have been
revised to better reflect current habitat conditions and to incorporate knowledge gained during the past 17 years of
RMANWR management. These revised recommendations will also be incorporated in the new CCP. Given the 15-year
lifespan of the HMP, the principles of adaptive management will be used to evaluate and modify management strategies
following completion of all restoration efforts.

The HMP identifies important wildlife resources on RMANWR and the management strategies that will be implemented
during the next 15 years to help ensure the appropriate life-cycle needs of these species are met at the appropriate spatial
scale. More than 300 species of wildlife have been documented on RMANWR, but many of these species occur in low
numbers or are not observed frequently. To identify priority resources of concern, refuge staff compiled a list of species
documented as priorities in various plans developed by national, regional, local, state, and private organizations and
compared this list to species that currently use, or potentially could use RMANWR habitats. Species that exhibited significant
overlap were selected as priority resources of concern and the habitat requirements (e.g., food, cover, area requirements) of
these species formed the basis for HMP goals, objectives, and management strategies. However, habitat resources are limited
given the size and isolated nature of the refuge; therefore, RMANWR staff used published scientific literature and
i
professional expertise to identify potential conflicts and optimize conditions for these species within the context of BIDEH.

Specifically, the goals and objectives of this HMP are designed to accomplish the following during the next 15 years (2013-
2028):

• Promote successful long-term establishment and maintenance of seeded restoration sites, as well as existing native
prairies and shrublands, to provide habitat for the resources of concern.

• Maintain the importance of RMANWR as a priority nesting site for burrowing owls (Athen cunicularia hypugaea)
along the Front Range of Colorado.

• Preserve a historically representative population of black-tailed prairie dogs (Cynomys ludovicianus; hereafter
referred to prairie dogs in the context of RMANWR).

• Provide additional nesting opportunities for resources of concern, including relevant grassland-dependent bird
species exhibiting population declines.

• Maintain a bison (Bison bison) population that contributes to the Department of the Interior’s Bison Conservation
Initiative and helps maintain the structure and composition of native and restored prairies necessary to support
priority grassland bird species.

• Provide habitat in the Educational Zone of the refuge for neo-tropical migratory bird species that are losing suitable
stop-over areas to urban development in the Denver-metro area.

• Provide long-term quality nesting and roosting habitat for the bald eagle (Haliaeetus leucocephalus).

• As one of the nation’s premier urban national wildlife refuges, the RMANWR provides a variety of unique public
education opportunities. This includes how one of the most environmentally contaminated sites in the United States
is being restored to a native prairie ecosystem.

ii
Table of Contents

Chapter 1: Introduction ........................................................................................................................................................ 1
Chapter 2: Background ......................................................................................................................................................... 7
Management zones ...................................................................................................................................................... 8
Physical or geographic setting ................................................................................................................................... 10
Habitat condition of the Refuge ................................................................................................................................. 13
Chapter 3: Resources of Concern ....................................................................................................................................... 27
Bald eagle .................................................................................................................................................................. 30
Swainson’s hawk ....................................................................................................................................................... 31
Burrowing owl ........................................................................................................................................................... 32
Cassin’s sparrow ........................................................................................................................................................ 34
Lark bunting .............................................................................................................................................................. 36
Grasshopper sparrow ................................................................................................................................................. 39
Black-tailed prairie dog ............................................................................................................................................. 41
American bison .......................................................................................................................................................... 42
Chapter 4: Goal & Objectives ............................................................................................................................................. 47
Habitat goals & objectives ......................................................................................................................................... 48
Prairie Zone ................................................................................................................................................. 48
Educational Zone ........................................................................................................................................ 56
Wildlife goals & objectives ....................................................................................................................................... 61
Chapter 5: Management Strategies .................................................................................................................................... 65
Native prairie ............................................................................................................................................................. 67
Riparian ..................................................................................................................................................................... 81
Shrubland .................................................................................................................................................................. 83
Woodlands ................................................................................................................................................................. 84
Lacustrine .................................................................................................................................................................. 86
Wetlands .................................................................................................................................................................... 87
Forage allocation ....................................................................................................................................................... 87
Management strategy constraints .............................................................................................................................. 90
Addendum ............................................................................................................................................................................ 93
Glossary ................................................................................................................................................................................ 95
Appendices ............................................................................................................................................................................ 97
Appendix A: Environmental Compliance ................................................................................................................. 97
Appendix B: List of Preparers and Reviewers ........................................................................................................ 119
Appendix C: Relationship to Other Management Plans .......................................................................................... 121
Appendix D: Summary of Habitat Goals and Objectives ........................................................................................ 123
Appendix E: Current Seed Mixes ............................................................................................................................ 127
Appendix F: Techniques for Seedbed Preparation and Weed Control .................................................................... 133
Appendix G: Neotropical Migratory Birds Found at the RMANWR ...................................................................... 137
Appendix H: A Forage Allocation Methodology for Use at the RMANWR .......................................................... 139
Bibliography ....................................................................................................................................................................... 147

iii
Tables

Table 1. Current acreages of habitat types found at the Rocky Mountain Arsenal NWR, 2013 .............................................. 18
Table 2. Noxious weeds found at the Rocky Mountain Arsenal NWR ................................................................................... 19
Table 3. Habitat needs for resources of concern & associated species, Rocky Mountain Arsenal NWR, 2013 ...................... 29
Table 4. Active acres of black-tailed prairie dog (BTPD) colonies and number of burrowing owl nests at the Rocky
Mountain Arsenal NWR ............................................................................................................................ 52
Table 5. Summary information for the bald eagle nest on Rocky Mountain Arsenal NWR.................................................... 55
Table 6. Bison population of the Rocky Mountain Arsenal NWR .......................................................................................... 62
Table 7. Potential strategies to accomplish habitat management plan objectives, Rocky Mountain Arsenal NWR................ 65
Table 8. Pesticides used at the Rocky Mountain Arsenal NWR and their environmental effects ........................................... 69
Table 9. Potential strategies to accomplish habitat management plan objectives, Rocky Mountain Arsenal NWR................ 87
Table 10. Deer census results at the Rocky Mountain Arsenal NWR, October 2012 .............................................................. 89
Table 11. Staffing resources necessary to implement the Rocky Mountain Arsenal NWR habitat management plan ............ 92
Table C. Relationship to other plans ...................................................................................................................................... 121
Table E-1. Current seed mix for Haplustoll soils (Overflow Range Site) ............................................................................. 127
Table E-2. Current seed mix for Ascalon/Bresser soils (Sandy Plains Range Site) ............................................................... 127
Table E-3. Current seed mix for Nunn Clay soils (Clayey Plains Range Site) ...................................................................... 128
Table E-4. Current seed mix for Petrocalcic soils (Gravel Breaks Range Site) ..................................................................... 129
Table E-5. Current seed mix for Santana Weld soils (Loamy Plains Range Site) ................................................................. 130
Table E-6. Seed mix for black-tailed prairie dog habitat restoration at the Rocky Mountain Arsenal NWR ........................ 130
Table F-1. Application rates and frequencies of supplemental water for establishing native perennial grasslands at the Rocky
Mountain Arsenal NWR .......................................................................................................................... 133
Table F-2. Timing and frequency of field practices to prepare seedbeds for seeding to permanent native vegetation .......... 133
Table H-1. Number of bison that can be supported on the RMANWR ................................................................................. 142
Table H-2. Number of bison that can be supported on current two pasture system ............................................................... 143

iv
Figures

Figure 1. Regional location of the Rocky Mountain Arsenal NWR .......................................................................................... 8
Figure 2. Location of habitat management zones at the Rocky Mountain Arsenal NWR ......................................................... 9
Figure 3. Ecoregions of the Rocky Mountain Arsenal NWR, Level IV Classification ........................................................... 10
Figure 4. Soil classes of the Rocky Mountain Arsenal NWR .................................................................................................. 12
Figure 5. Habitat types at the Rocky Mountain Arsenal NWR ................................................................................................ 18
Figure 6. Natural resource areas of special interest at the Rocky Mountain Arsenal NWR .................................................... 21
Figure 7. Topographic alteration associated with cleanup at the Rocky Mountain Arsenal NWR .......................................... 25
Figure 8. Location of the Rocky Mountain Arsenal NWR in relation to Bird Conservation Region 18 ................................. 28
Figure 9. Current distribution of black-tailed prairie dogs at the Rocky Mountain Arsenal NWR ......................................... 53
Figure 10. Proposed zones for black-tailed prairie dog management at the Rocky Mountain Arsenal NWR ......................... 54
Figure 11. Irrigation & water infrastructure at the Rocky Mountain Arsenal NWR ............................................................... 71
Figure H-1. Range sites within the Native Prairie Zone accessible to bison grazing on the Rocky Mountain Arsenal NWR
............................................................................................................................................................................................... 144

v
vi