Rocky Mountain Arsenal National Wildlife Refuge Habitat Management Plan
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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. Draft 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., 143 p. i 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 Oil 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. Therefore, 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 potential 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 the nation’s premier urban wildlife refuge, the RMANWR provides a variety of unique public education opportunities. This includes how one of the most environmentally contaminated sites in the United States can be 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 ................................................................................................................................... 9 Habitat Condition of the Refuge ................................................................................................................................ 11 Chapter 3: Resources of Concern ....................................................................................................................................... 23 Bald eagle .................................................................................................................................................................. 25 Swainson’s hawk ....................................................................................................................................................... 27 Burrowing owl ........................................................................................................................................................... 28 Cassin’s sparrow ........................................................................................................................................................ 30 Lark bunting .............................................................................................................................................................. 32 Grasshopper sparrow ................................................................................................................................................. 34 Black-tailed prairie dog ............................................................................................................................................. 36 American bison .......................................................................................................................................................... 37 Chapter 4: Goal & Objectives ............................................................................................................................................