Union Slough NWR Habitat Management Plan January 2016

Habitat Management Plans provide long-term guidance for management decisions, set goals, objectives and strategies needed to accomplish refuge purposes, and identify the Fish and Wildlife Service’s best estimate of future needs. These plans detail program planning levels that are sometimes substantially above current budget allocations and as such, are primarily for Service strategic planning and program prioritization purposes. The plans do not constitute a commitment for staffing increases, operational and maintenance increases, or funding for future land acquisition.

The National Wildlife Refuge System, managed by the U.S. Fish and Wildlife Service, is the world's premier system of public lands and waters set aside to conserve America's fish, wildlife and habitats. Since the designation of the first wildlife refuge in 1903, the System has grown to encompass more than 150 million acres, 550 national wildlife refuges and other units of the Refuge System, plus 38 wetland management districts.

Union Slough National Wildlife Refuge Habitat Management Plan i

Executive Summary

Located in north-central Iowa in the southeast corner of the Prairie Pothole Region, Union Slough National Wildlife Refuge (NWR) provides critical habitat for native prairie and wetland wildlife in a landscape dominated by intensive agriculture. Union Slough NWR, which includes seven adjacent Union Slough Waterfowl Production Areas (WPAs), contains a diverse mixture of habitats including marshes, river bottomlands, and prairies/grasslands. Together, these areas total approximately 3,334 acres that follow a nine-mile stretch of Union Slough, a relict pre-glacial riverbed. The habitats of the Refuge function as a regionally significant nesting and stopover site for migratory waterfowl and birds and support unique assemblages of resident plants and wildlife. .

The Refuge’s Resources of Concern (ROC) were identified by reviewing the species known to occur within Union Slough NWR, as well as those identified in local and regional conservation plans, and analyzing their relation to the biological integrity, diversity, and environmental health (BIDEH) of the habitats present on the Refuge. Based on this analysis, the Refuge identified 36 priority ROCs, which includes several birds, a plant, two insects, and a natural community. Focal ROCs serve as indicators and representatives for other species and groups that may utilize similar habitats. As part of the ROC identification process, habitats were also prioritized for future management. Marsh and prairie/ grassland habitats are the two highest priority habitats because they help to meet the Refuge’s designated purpose for migratory waterfowl. This prioritization was also balanced with the Refuge’s overall strategy of implementing management on one quarter of the Refuge annually on a rotating basis.

The three most important issues that impact the ecological integrity of the Refuge and influence Refuge management are:

• Invasive plant species reduce native plant diversity and vegetative structure and threaten the federally-threatened prairie bush clover (Lespedeza leptostachya).

• Increased tile drainage in the agriculturally-dominated watersheds increases the frequency of flooding on the Refuge and reduces the ability to provide suitable habitats for some waterfowl and waterbirds.

• Sediments, nutrients and chemicals from surrounding agricultural land uses accumulate on the refuge to the detriment of refuge habitats and wildlife.

Union Slough National Wildlife Refuge Habitat Management Plan iii

Table of Contents

Executive Summary ...... iii Acronyms ...... vi Chapter 1...... 1 1.1 Scope and Rationale...... 2 1.2 Legal Mandates ...... 3 1.3 Relation to Service Policy ...... 4 1.4 Relation to Other Plans ...... 5 Chapter 2...... 11 2.1 Refuge Location and Description ...... 12 2.2 Management Units ...... 16 2.3 Physical/Geographic Setting and Historic Condition ...... 17 2.4 Current Natural and Anthropogenic Disturbances ...... 22 2.5 Current Refuge Conditions and Resources ...... 24 Chapter 3...... 30 3.1 Introduction ...... 31 3.2 Identification of Refuge Resources of Concern ...... 31 3.3 Biological Integrity, Diversity, and Environmental Health ...... 33 3.4 Priority Refuge Resources of Concern ...... 39 3.5 Priority Habitat Types and Associated Priority Species ...... 52 3.6 Conflicting Habitat Needs ...... 53 3.7 Adaptive Management ...... 53 Chapter 4...... 54 4.1 Background ...... 55 4.2 Habitat Goals and Objectives ...... 57 Chapter 5...... 67 5.1 Development of Management Strategies and Prescriptions ...... 68 5.2 Annual Management Decision Making and Prioritization ...... 68 5.3 Management Strategies by Habitat Objective ...... 69 References ...... 75 Appendix A ...... 83

Union Slough National Wildlife Refuge Habitat Management Plan iv Appendix B ...... 91 Appendix C ...... 92 Appendix D ...... 94

Figures

Figure 1-1 Union Slough NWR within BCR 11 and PIF 40

Figure 2-1 Location of Union Slough NWR

Figure 2-2 Union Slough NWR within major watersheds

Figure 2-3 Union Slough NWR and Nearby WPAs

Figure 2-4 Prairie Pothole Region of North America

Figure 2-5 Presettlement Vegetation in the Vicinity of Union Slough NWR

Figure 2-6 Union Slough NWR within the Plains and Prairie Potholes LCC

Figure 2-7 1992 Vegetation in the Vicinity of Union Slough NWR

Figure 4-1 Union Slough NWR Management Units/Subunits

Tables

Table 3-1 Summary of Habitats that Represent Existing BIDEH on Union Slough NWR

Table 3-2 Habitat Requirements for Union Slough Priority ROCs

Table 3-3 Priority ROCs and Other Benefitting Species on Union Slough NWR

Table 3-4 Priority Habitats and their Limiting Factors on Union Slough NWR

Table 4-1 Union Slough NWR Unit/Subunit Management Treatment Schedule

Table 5-1 Distribution of Refuge Habitats Across Management Units at Union Slough NWR

Appendices

Appendix A Potential Resources of Concern

Appendix B ROCSTAR Scoring Evaluations

Appendix C HMP Development Team

Appendix D Grazing/Haying Program Management Plan

Union Slough National Wildlife Refuge Habitat Management Plan v

Acronyms

AHWP Annual Habitat Work Plan BCR Bird Conservation Region BIDEH Biological Integrity, Diversity, and Environmental Health CCP Comprehensive Conservation Plan CFA Cooperative Farming Agreement CMP Comprehensive Management Plan DNR Department of Natural Resources GMGT Genetically-modified, Glyphosate-tolerant HMP Habitat Management Plan LCC Landscape Conservation Cooperative MSIM Multiple Species Inventory and Monitoring NAWMP North American Waterfowl Management Plan NEPA National Environmental Policy Act NVCS National Vegetation Classification System NWR National Wildlife Refuge NWRS National Wildlife Refuge System PIF Partners In Flight PPJV Prairie Pothole Joint Venture PPR Prairie Pothole Region PUP Pesticide Use Proposal ROC Resources of Concern SUP Special Use Permit USDA U.S. Department of Agriculture USFWS U.S. Fish and Wildlife Service USGS U.S. Geological Survey

Union Slough National Wildlife Refuge Habitat Management Plan vi Chapter 1. Introduction

Chapter 1. Introduction

Native prairie habitat at Union Slough NWR. Photo credit: USFWS Midwest Region

1.1 Scope and Rationale 1.2 Legal Mandates 1.3 Relation to Service Policy 1.4 Relation to Other Plans

Union Slough National Wildlife Refuge Habitat Management Plan 1 Chapter 1. Introduction

1.1 Scope and Rationale

In 1996, the U.S. Fish and Wildlife Service (FWS, Service) published the Final Comprehensive Management Plan (CMP) for Union Slough National Wildlife Refuge (NWR). As part of the planning and National Environmental Policy Act (NEPA) processes associated with the CMP, the FWS evaluated the effects of implementing a broad range of fish, wildlife, plant, and habitat management programs and techniques to achieve Union Slough NWR purposes, goals, and objectives, to address FWS trust resource responsibilities, to maintain and, where appropriate, restore biological integrity, diversity, and environmental health (BIDEH), and to support the National Wildlife Refuge System (NWRS, System) mission 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 of Americans.

In addition, while developing the CMP, Union Slough NWR created the following vision statement that ties together their watershed, partner, and wildlife goals:

Union Slough National Wildlife Refuge, located in Kossuth County, Iowa, will soon be transformed into a wildlife refuge for the 21st century. The Refuge watershed will become a model of sustainability showing how modern agriculture and natural areas can thrive side by side. Through new partnerships, the watershed will see widespread use of Best Management Practices, Precision Farming, Integrated Crop Management, and other conservation and environmental farming practices. The Refuge will expand to support and maintain a community of organisms having a species composition, diversity, and functional organization comparable to that of native habitats of this region. Wildlife abundance and educational opportunities will increase to attract students of all ages and abilities to learn about the Refuge watershed ecosystem. Local communities will promote the Refuge as a regional destination, which will contribute to the local economy.

The vision statement was developed in the 1990s. The partnerships and changes in farming best management practices in the watershed haven’t been either fully developed or haven’t been pursued due to economic and cultural factors that led to an intensification of agricultural practices over the past 20 years. Current management on the Refuge focuses on restoring and maintaining native habitats within the context of a watershed heavily influenced by agriculture.

The Union Slough NWR Habitat Management Plan (HMP) provides guidance for habitat management on the Refuge’s existing land base. It will help facilitate thoughtful and explicit planning for habitat objectives and management actions. Additionally, the HMP will inform the Refuge Inventory and Monitoring Plan (IMP) and Annual Habitat Management Plans.

This HMP was prepared in accordance with guidance for developing HMPs provided by the Service’s Habitat Management Plans policy (620 FW 1). It also complies with all applicable laws, regulations, and policies governing the management of units of the NWRS.

The HMP lifespan is 15 years and may be peer reviewed every 5 years as necessary. The Refuge Manager may modify the HMP at any time if new information suggests that the plan is inadequate or on-Refuge resources would benefit from changes to the plan.

Union Slough National Wildlife Refuge Habitat Management Plan 2 Chapter 1. Introduction

1.2 Legal Mandates

The FWS is the primary federal agency responsible for conserving, protecting, and enhancing fish and wildlife and their habitats for the continuing benefit of the American people. Specific responsibilities include enforcing federal wildlife laws, managing migratory bird populations, restoring nationally significant fisheries, administering the Endangered Species Act, and restoring wildlife habitat such as wetlands. The mission of the Service is to work with others to conserve, protect, and enhance fish, wildlife, and plants and their habitats for the continuing benefit of the American people.

The Service's role also includes managing the NWRS, the world's largest collection of lands specifically managed for fish and wildlife. The System is a network of more than 550 national wildlife refuges and other units plus 38 wetland management districts encompassing more than 150 million acres of public land and water.

Refuge Purpose Statements are primary to the management of each refuge within the System. The Purpose Statement is derived from the legislative authority used to acquire specific refuge lands and is, along with NWRS goals, the basis on which primary management activities are determined. Additionally, these statements are the foundation from which allowed uses of refuges are determined through a defined compatibility process.

Union Slough NWR was established by Franklin D. Roosevelt (Executive Order 7976, dated September 14, 1938) primarily to assist with the production and management of waterfowl in the Mississippi Flyway. The purpose of the Refuge is to provide "a refuge and breeding ground for migratory birds and other wildlife...” Union Slough NWR also administers the 25,000 acre Iowa Wetland Management District (WMD) and two tracts totaling 309 acres of the Northern Tallgrass Prairie NWR. All fee title, (with the exception of the seven Union Slough WPA tracts) and easement tracts associated with the Iowa WMD and Northern Tallgrass Prairie NWR will be addressed in the Habitat Management Plan for either the Iowa WMD or the Northern Tallgrass Prairie NWR, and are not covered by this HMP. Key provisions of applicable legal mandates for Union Slough NWR are described here:

“... as a refuge and breeding ground for migratory birds and other wildlife...” Executive Order 7976, dated Sept. 14, 1938.

"... for use as an inviolate sanctuary, or for any other management purpose, for migratory birds." 16 U.S.C. § 715d (Migratory Bird Conservation Act).

"... conservation, management, and ... restoration of the fish, wildlife, and plant resources and their habitats ... for the benefit of present and future generations of Americans..." 16 U.S.C. § 668dd(a)(2) (National Wildlife Refuge System Administration Act).

Other legislation that directs refuge management includes the National Wildlife Refuge System Administration Act (1966) as amended by the National Wildlife Refuge System Improvement Act (1997) 16 U.S.C. 668dd668ee (Refuge Improvement Act). This defines the NWRS and authorizes the Secretary of the Interior to permit any use of a refuge provided such use is compatible with the major purposes for which the refuge was established.

Union Slough National Wildlife Refuge Habitat Management Plan 3 Chapter 1. Introduction

The landmark Refuge Improvement Act prepared the way for a renewed vision for the future of the refuge system where:

• Wildlife comes first • Refuges are cornerstones for biodiversity and ecosystem-level conservation • Lands and waters of the System are biologically healthy • Refuge lands reflect national and international leadership in habitat management and wildlife conservation

Considered the "Organic Act” of the NWRS, the Refuge Improvement Act clearly defined a unifying mission for the System, established the legitimacy and appropriateness of the six priority public uses (hunting, fishing, wildlife observation, photography, environmental education, and interpretation), established a formal process for determining compatibility, established the responsibilities of the Secretary of Interior for managing and protecting the System; and required a Comprehensive Conservation Plan (CCP) for each refuge by the year 2012. The Refuge Improvement Act amended portions of the Refuge Recreation Act and National Wildlife Refuge System Administration Act of 1966.

1.3 Relation to Service Policy

Important guidance for habitat management on refuges has already been provided by several key policies outlined by the Service. These policies are included within the Service Manual, which documents re-delegation of the FWS Director's authority, prescribes the policies and procedures for administrative activities and program operations, and steps down compliance with other requirements, such as statutes, Executive Orders, Departmental directives, and regulations of other agencies (USFWS 2013). Several policies are pertinent to the development of HMPs:

Habitat Management Planning Policy - 620 FW 1 (USFWS 2002) This chapter of the Service Manual establishes Service policy for planning habitat management within the NWRS. The guidance in this chapter applies to the development of HMPs and Annual Habitat Work Plans (AHWP) and discusses their relationship to refuge CCPs. The policy and guidance in this chapter describe strategies and implementation schedules for meeting CCP goals and objectives. We utilized this policy to direct the content and considerations addressed in this HMP.

Biological Integrity, Diversity, and Environmental Health Policy - 601 FW 3 (USFWS 2003a) This chapter provides policy for maintaining and restoring, where appropriate, the biological integrity, diversity, and environmental health (BIDEH) of the NWRS. The policy is a System directive for refuge managers to follow while achieving refuge purpose(s) and System mission. It provides guidance for conservation and management of the broad spectrum of fish, wildlife, and habitat resources found on refuges and associated ecosystems. Further, it provides refuge managers with an evaluation process to analyze their refuge and recommend the best management direction to prevent further degradation of environmental conditions, and where appropriate and in concert with refuge purposes and System mission, restore lost or severely degraded components. We consider the role of BIDEH in our habitat management to the extent that it supports the Refuge purpose, goals, and objectives.

Draft Inventory and Monitoring Policy - 701 FW 2 (USFWS 2012) This updated chapter (currently in draft form) provides guidance for developing a Refuge Inventory and Monitoring Plan (IMP) for a station of the NWRS. It describes priorities for natural resource surveys, selection and design of survey protocols, data storage and analysis, and reporting results. It accommodates all levels of natural resource surveys, from the station level to participation in landscape, regional, national, and international inventory and monitoring programs, both internal and external to the Service. Overall, this policy promotes consistency in

Union Slough National Wildlife Refuge Habitat Management Plan 4 Chapter 1. Introduction the planning and implementation of inventory and monitoring throughout the System. We utilize its guidance to direct the development of inventory and monitoring strategies outlined within the IMP, which are guided by the goals and objectives of this HMP.

1.4 Relation to Other Plans

Important guidance for wildlife habitat management at the Refuge has already been provided by several important Refuge-specific, regional, national, and international plans.

Interagency Plans

U.S. Department of the Interior Adaptive Management Guide (Williams et. al 2009) The planning team used adaptive management principles in the development of this HMP, and the Refuge will use adaptive management to respond to changing conditions that impair the ability to measure and achieve habitat objectives. It should be noted that although aspects of the U.S. Department of the Interior’s (DOI) adaptive management guide were used throughout the entire process of developing this HMP, it is not a required aspect of completing an HMP. As such, the processes outlined below were strictly used as guidance. Service policy for HMP development (620 FW 1, 601 FW 3, 701 FW 2) was the overarching direction used to complete this HMP. As defined by the DOI (Williams et al. 2009), adaptive management is:

…a decision process that promotes flexible decision making that can be adjusted in the face of uncertainties as outcomes from management actions and other events become better understood. Careful monitoring of these outcomes both advances scientific understanding and helps adjust policies or operations as part of an iterative learning process. Adaptive management also recognizes the importance of natural variability in contributing to ecological resilience and productivity. It is not a ‘trial and error’ process, but rather emphasizes learning while doing. Adaptive management does not represent an end in itself, but rather a means to more effective decisions and enhanced benefits. Its true measure is in how well it helps meet environmental, social, and economic goals, increases scientific knowledge, and reduces tensions among stakeholders.

There are two phases in implementing the DOI’s adaptive management procedures: the “Set-up Phase” (Steps 1-5), where key components of the program are developed, and the “Iterative Phase” (Steps 6-9), where components of the program are put in practice and linked together in a data-driven, results-oriented sequential decision making process.

Step 1 – Stakeholder Involvement Engage with stakeholders to assess the problem(s) and reach agreement about scope, objectives, and potential management actions. Identify and engage all stakeholders to the extent feasible, and make all steps of the adaptive management process open and transparent.

Step 2 – Objectives Identify clear, measureable, and agreed-upon management objectives to guide decision making and evaluate management effectiveness over time. Objectives should address the resource issue and reflect the social, economic, and/or ecological values of the stakeholders. Objectives should be specific and unambiguous, measureable with the appropriate field data, achievable but challenging, results-oriented, and time fixed.

Step 3 – Management Actions Identify potential management actions for decision making. Potential actions should consist of activities that are under management control. Alternative actions should be explicit and documented.

Union Slough National Wildlife Refuge Habitat Management Plan 5 Chapter 1. Introduction

Step 4 – Models Identify models that characterize different ideas and hypotheses about how the system works. The models should: 1) be understood to change over time; 2) be focused on key components of interest; 3) describe resource changes directly influenced by management; 4) incorporate fluctuating environmental conditions; 5) apply a cost/benefit analysis; and 6) be calibrated with available data and knowledge.

Step 5 – Monitoring Plans Design and implement a monitoring plan to track resource status and other key resource attributes. The monitoring plan should include procedures to: 1) evaluate progress towards achieving objectives, 2) determine resource status in order to identify management actions, 3) increase the understanding of resource dynamics by comparing predictions and results, and 4) enhance and develop models of resource dynamics.

Step 6 – Decision Making Select management actions from a comprehensive list of all possible actions based on management objectives, resource conditions, and enhanced understanding of the ecological integrity of the refuge. Actions should be based on objectives, and both actions and objectives may need to be adjusted over time to account for changed resource conditions or updated understanding of resources and resource dynamics.

Step 7 – Follow-up Monitoring Use monitoring to track system responses to management actions. Monitoring should occur after management actions have taken place, but in certain situations (e.g. population monitoring) it may be necessary to monitor before the implementation of actions to establish baseline information.

Step 8 – Assessment Compare predicted versus observed change in resource status to improve understanding of resource dynamics. Using monitoring results, these assessments should include parameter estimation, comparative assessments, and prioritization of management alternatives. The results of these comparisons are used to update the understanding of management impacts, inform the selection of management actions, and evaluate the effectiveness of management actions.

Step 9 – Iteration Periodically re-visit the selected management actions (step 6) and amend them, if necessary, based upon the results of steps 7 and 8. Occasionally it may be necessary to return to step 1 and repeat the entire process.

Certain aspects of adaptive management as outlined in steps 1 to 9 were completed as part of the Refuge’s 1996 CMP; others were revisited or completed with the development of this HMP. Specifically, Step 1 was utilized to research the Refuge history (Chapter 2), select priority resources (Chapter 3), and to develop updated goals, objectives, and strategies (Chapters 4 and 5). In certain cases outside professionals (e.g. staff from the Iowa Department of Natural Resources or local universities) were consulted for their expertise on the wildlife and habitat of the Refuge. In other instances, stakeholder engagement involved non-direct interactions between the planning team and other experts within the Service as well as consulting peer- reviewed and published literature (e.g. state, regional, national and international plans listed below). While Step 2 was addressed in the 1996 CMP, it was revisited in the HMP with the modification of goals and objectives as outlined in Chapter 4; these modifications took into account aspects of Steps 3 and 4. Step 5 requires the Refuge to establish and maintain a monitoring program to ensure that changing conditions can be detected and responded to adequately and efficiently. The monitoring program will be created in accordance with 701 FW 2 and will be developed as a step down plan (the IMP). Step 6 has been achieved with the strategies as outlined in Chapter 5; these strategies will be revisited every 5 years with the

Union Slough National Wildlife Refuge Habitat Management Plan 6 Chapter 1. Introduction internal review and update of the HMP as mandated in Service policy (620 FW 1). Steps 7 to 9 will be achieved on an annual basis over the 15 year life of this HMP.

State, Regional, National, and International Plans

The habitat goals and objectives and habitat management strategies described in this HMP are consistent with many other local, regional, and national conservation plans. Many of the plans listed below were key resources used to develop the HMP.

North American Waterfowl Management Plan (NAWMP 2012) The North American Waterfowl Management Plan was first signed in 1986 and has been updated several times since that time. The focus of the plan has been on sustaining abundant waterfowl populations by conserving landscapes, through partnerships that are guided by sound science. To achieve the NAWMP vision in today’s environment, the most recent version of the Plan sets forth three overarching goals for waterfowl conservation:

Goal 1: Abundant and resilient waterfowl populations to support hunting and other uses without imperiling habitat.

Goal 2: Wetlands and related habitats sufficient to sustain waterfowl populations at desired levels, while providing places to recreate and ecological services that benefit society.

Goal 3: Growing numbers of waterfowl hunters, other conservationists and citizens who enjoy and actively support waterfowl and wetlands conservation.

U.S. Shorebird Conservation Plan (Brown et al. 2001) and Northern Plains and Prairie Potholes Regional Shorebird Conservation Plan (Skagen and Thompson 2000) The U.S. Shorebird Conservation Plan outlines shorebird conservation status, populations, and priorities. It also recommends monitoring programs and identifies regional conservation goals and strategies at a national level. The Prairie Potholes Regional Shorebird Conservation Plan provides similar information, but is focused on the Prairie Pothole Region (PPR).

North American Waterbird Conservation Plan (Kushlan et al. 2002), Northern Prairie and Parkland Waterbird Conservation Plan (Beyersbergen et al. 2004) The North American Waterbird Conservation Plan provides an international, landscape-scale framework and guide for conserving waterbirds. It focuses on colonial-nesting waterbirds and sea birds, a portion of which use the PPR. The Northern Prairie and Parkland Waterbird Conservation Plan is more directly applicable to Union Slough NWR, as it addresses species and conservation issues particular to the Refuge area.

Partners in Flight North American Landbird Conservation Plan (Rich et al. 2004) and Bird Conservation Plan for the Northern Tallgrass Prairie (Fitzgerald et al. 1998) The North American Landbird Conservation Plan was developed to provide priorities and objectives to guide landbird conservation at a continental scale. Partners in Flight (PIF) developed a regional plan for the Northern Tallgrass Prairie in 1998, and revised its species assessment scores by Bird Conservation Regions (BCRs) (Union Slough NWR is in BCR 11 – Prairie Potholes, Figure 1-1) in 2010. Those scores can be found by accessing the PIF Species Assessment Database at http://rmbo.org/pifdb/.

Union Slough National Wildlife Refuge Habitat Management Plan 7 Chapter 1. Introduction

Figure 1-1. Union Slough NWR within BCR 11 and PIF 40.

Union Slough National Wildlife Refuge Habitat Management Plan 8 Chapter 1. Introduction

Prairie Pothole Joint Venture Implementation Plan (Ringelman 2005) The Prairie Pothole Joint Venture (PPJV) was originally established in 1987 under the North American Waterfowl Management Plan. Since that time, it has expanded its focus from waterfowl to planning for the conservation of all bird guilds. This most recent implementation plan provides stepped-down objectives for waterfowl, shorebirds, waterbirds, and landbirds.

Securing a Future for Fish and Wildlife: A Conservation Legacy for Iowans (Zohrer et al. 2005) This statewide strategic plan guides habitat management for wildlife species of greatest conservation need. It is particularly helpful to the Refuge because it identifies conservation issues and strategies at a smaller, more local (i.e., statewide) scale than most other plans.

Refuge Plans

Union Slough NWR Comprehensive Management Plan The Union Slough NWR Comprehensive Management Plan (CMP) was developed in 1996 as a response to concerns regarding the decline of grassland and wetland habitat and their associated wildlife (USFWS 1996). The CMP identifies specific Refuge goals, objectives, and strategies that define what the Refuge must do to satisfy its purpose, legal mandates, and the needs of all interested parties in what and how the Refuge performs.

An HMP is normally a step-down plan from a previously completed CCP. The plan written for Union Slough in 1996 was one of the Refuge System’s first completed comprehensive plans and was called a CMP. The planning process evolved, and soon after the Union Slough NWR CMP was finished, the plans became known as CCPs. A CCP is a long-term, inclusive plan that guides all aspects of conservation on a refuge, including habitat management, public use, and refuge operations for a 15-year period. Because the Union Slough CMP is at the end of its 15- year term, it will be revised as a CCP in the future. In the interim, the CMP functions as Union Slough NWR’s CCP and this HMP will be used to guide the Refuge’s management activities. Because the wildlife and habitat goals and objectives in the CMP’s Chapter 3 were not specific enough for the purposes of the HMP, new goals and objectives have been written for this HMP and used to guide management until a new CCP is developed. The HMP will be used to inform the new CCP when it is developed. The goals and objectives contained within this HMP support and further achieve the purpose for which the Refuge was established.

Union Slough NWR Grassland Management Plan Union Slough NWR is located in the heart of the PPR and the Northern Tallgrass Prairie ecosystem. As stated in the CMP, the Habitat and Wildlife Management Goal for Union Slough is to restore and preserve a community of life typical of the tallgrass prairie ecosystem. The Grassland Management Plan includes goals to preserve all remnant tallgrass prairie, preserve and restore buffers around wetlands, and preserve and restore waterfowl and grassland bird breeding habitat. These goals, and the strategies needed to accomplish these goals, are included in this HMP.

Union Slough NWR/Iowa WMD/Northern Tallgrass Prairie NWR Wildland Fire Management Plan Service policy mandates that any refuge or wetland management district that has “vegetation capable of sustaining fire” must have a Fire Management Plan (FMP). The Union Slough NWR/Iowa WMD/Northern Tallgrass Prairie NWR Fire Management Plan (USFWS 2009a) was developed in response to this policy. The FMP addresses wildland fire events with guidelines on the level of protection needed to ensure personal and public safety, and to protect facilities and resources. The Fire Management Plan serves as a step-down plan for this HMP.

Union Slough NWR Grazing/Haying Program Management Plan Service guidance in Region 3 requires the development of a grazing/haying program management plan when either grazing or haying is used as a management tool. Appendix D provides the plan developed specifically for Union Slough NWR. Service guidance requires that grazing and haying must support the Refuge’s BIDEH and biological purpose(s). Grazing and

Union Slough National Wildlife Refuge Habitat Management Plan 9 Chapter 1. Introduction haying should be completed using best available science-based Best Management Practices and monitored for effectiveness in desired outcome.

Union Slough National Wildlife Refuge Habitat Management Plan 10 Chapter 2. Background

Chapter 2. Background

Prairie pothole landscape in the Iowa Wetland Management District. Photo Credit: USFWS Midwest Region

2.1 Refuge Location and Description 2.2 Management Units 2.3 Physical/Geographic Setting and Historic Condition 2.4 Current Natural and Anthropogenic Disturbances 2.5 Current Refuge Conditions and Resources

Union Slough National Wildlife Refuge Habitat Management Plan 11 Chapter 2. Background

2.1 Refuge Location and Description

Union Slough National Wildlife Refuge (NWR) is located in north-central Iowa’s Kossuth County, about 55 miles north of Fort Dodge, Iowa, 160 miles southwest of Minneapolis, Minnesota, and 130 miles north of Des Moines, Iowa (Figure 2-1). The Refuge encompasses approximately 2,845 acres along a 9-mile stretch of Union Slough, Buffalo Creek, and the East Fork of the Des Moines River (Figure 2-1).

Union Slough is a pre-glacial riverbed that forms the “union” between the watersheds of the Blue Earth River and the East Fork of the Des Moines River. The northern 75% of the Refuge is within the Blue Earth River watershed, while the southern quarter is within the Des Moines River Watershed (Figure 2-2).

An approved acquisition boundary was identified during the development of the Union Slough NWR Comprehensive Management Plan (CMP; Figure 2-3). Since that time, eight tracts within the approved acquisition boundary were purchased through the Small Wetlands Acquisition Program (SWAP). These tracts are Waterfowl Production Areas (WPAs) and are administered as part of the Iowa Wetland Management District. One of these tracts, Wapati WPA, is separated from Union Slough NWR by a county road. A second tract, Maynard Reece WPA, is separated from the Refuge by a distance of more than a mile. These two tracts are managed independently of Union Slough NWR. The remaining six tracts are immediately adjacent to the Refuge and are known as Union Slough WPA. For ease of management, they have been essentially adjoined with Union Slough NWR and are managed as part of the Refuge, and thus are included in this Habitat Management Plan (HMP; Figure 2-2). Henceforth in this HMP, all discussions of Union Slough NWR include these six WPA tracts, unless otherwise noted. The six tracts encompass approximately 489 acres, which together with the 2,845 acres of Union Slough NWR, increases the total area managed under this HMP to approximately 3,334 acres. Of this area, the Refuge contains roughly 1,200 acres of marsh, 1,590 acres of diverse uplands, 536 acres of river bottomlands, and 8 acres of old gravel pits under normal water conditions.

Union Slough National Wildlife Refuge Habitat Management Plan 12 Chapter 2. Background

Figure 2-1. Location of Union Slough NWR.

Union Slough National Wildlife Refuge Habitat Management Plan 13 Chapter 2. Background

Figure 2-2. Union Slough NWR within major watersheds.

Union Slough National Wildlife Refuge Habitat Management Plan 14 Chapter 2. Background

Figure 2-3. Union Slough NWR and Nearby WPAs.

Union Slough National Wildlife Refuge Habitat Management Plan 15 Chapter 2. Background

2.2 Management Units

Union Slough NWR is divided into seven management units, which are based primarily on the locations of county roads or dikes (Figure 2-3). Most management units are divided by county roads except for Units 2 and 3, which are separated by a dike with a water control structure. With the exception of the county road between Unit 1 and the Buffalo Creek Unit, a water control structure is located at all of the county roads separating management units. The water control structures are located in an old dredge ditch that was constructed in Union Slough to attempt to drain the area prior to the Refuge’s establishment. Units 1 to 5 comprise the original core of the Refuge. The other two units, the Schwob Marsh Unit and the Buffalo Creek Unit, became part of Union Slough NWR in the mid-1980s through a land trade with the State of Iowa.

A brief description of each management unit appears below.

Schwob Marsh Unit (265 Acres) The Schwob Marsh Unit contains approximately 140 acres of marsh and 125 acres of upland habitat. Unlike the other units on the Refuge, there is no water control structure on the main outlet ditch in this unit, because some of the bottom ground is privately owned cropland. To manage water, the marsh has been subdivided with dikes to create three separate pools. Because the dikes in this unit were constructed from inferior materials, they tend to be subject to regular seepage and frequent blow outs. While each pool is equipped with a water control structure, shallow water depths have led to suboptimal wetland vegetation conditions. As a result, dense, monotypic stands of reed canary grass (Phalaris arundinacea) have invaded the majority of the wetland areas of this unit. Vegetation types on the upland portions of this unit include remnant prairie, planted native grass, and introduced cool season grasses.

Unit 5 (244 Acres) Unit 5 contains a dike that divides the 144 acres of wetland in this unit into two separate pools: the western D2 Pool (83 acres) and the eastern Ruddy Pool (61 acres). The water control structure on the north end of this unit can control both pools. The Ruddy Pool has two additional water control structures, which allow the two pools to be managed separately, if desired. This unit has a mix of open water and emergent wetland vegetation. The vegetation within the 100 acres of upland in this unit is primarily characterized as remnant prairie. The west side of the unit is a high quality remnant prairie known as Vanishing Prairie, which contains a population of the federally-threatened prairie bush clover (Lespedeza leptostachya). Crown vetch (Coronilla varia) has invaded this unit and poses a serious threat to the prairie bush clover and other native prairie plants.

Unit 4 (298 Acres) Unit 4 contains the 167 acres of marsh referred to as the D1 Pool. The water control structure is located at the north end of Unit 4. The D1 Pool typically has a mix of open water to emergent wetland vegetation. The vegetation within the 131 upland acres in this unit includes degraded remnant prairie, planted native grasses, and grasslands dominated by smooth brome (Bromus inermis) and/or Kentucky bluegrass (Poa pratensis).

Unit 3 (535 Acres) Unit 3 contains 277 acres of wetland, 250 acres of upland, and 8 acres of old gravel pits. The marsh in this unit, known as the C Pool, is dominated by cattail (Typha spp.). There are water control structures at both ends of this pool. Upland vegetation in this unit consists of degraded remnant prairie, diverse reconstructed prairie, planted native grasses, and introduced cool- season grasses. The gravel pits found in this unit contain permanent open water. Crown vetch is a serious problem in some upland areas in this unit.

Unit 2 (867 Acres) With 366 acres of marsh and 501 acres of upland, Unit 2 is the largest habitat unit on the Refuge. The marsh in this unit, known as the B Pool, is primarily open water. This pool frequently

Union Slough National Wildlife Refuge Habitat Management Plan 16 Chapter 2. Background produces abundant stands of submergent vegetation that consist mainly of sago pondweed (Stuckenia pectinata). Water control structures are located at both ends of this pool, with the water control structure on the south end located on the Unit 1 side of the county road. The upland portion of this unit contains high quality remnant prairie, diverse reconstructed prairie, planted native grass, introduced cool-season grass, and a 10-acre grove of trees.

Unit 1 (576 Acres) The marsh in this unit is known as the A Pool and is 106 acres in size. It typically has a mix of open water and emergent wetland vegetation. Water control structures can be found at both ends of this pool. Within the 324 acres of upland in this unit, vegetation consists of remnant prairie, diverse reconstructed prairie, planted native grasses, grasslands dominated by smooth brome and/or Kentucky bluegrass, and scattered shrubs and trees. This unit also contains 146 acres of river bottomlands. Vegetation in the bottomlands is dominated by reed canary grass and trees, primarily green ash (Fraxinus pennsylvanica).

Buffalo Creek Unit (549 Acres) The Buffalo Creek Unit, comprised of approximately 390 acres of river bottomlands, provides different habitat from the other management units on the Refuge. The majority of this unit was added to the Refuge in 1986 through a land trade with the State of Iowa. At that time, there was a dam across Buffalo Creek that was used to create a 150-acre impoundment. Due to legal issues with upstream landowners, the dam was removed in August 2011. The annual flooding of the impoundment area when the dam was in place helped to limit tree establishment in that portion of the Buffalo Creek floodplain. Maintaining the treeless character of this area is more challenging now that the dam has been removed. The vegetation in these bottomlands consists mostly of reed canary grass, rice cutgrass (Leersia oryzoides), and trees. The most common tree species include green ash, silver maple (Acer saccharinum), willow (Salix spp.), and eastern cottonwood (Populus deltoides). There are also significant stands of smartweed (Persicaria spp.), river bulrush (Bolboschoenus fluviatilis), and other wetland plants in the oxbows and other lower portions of the floodplain. The Buffalo Creek unit also contains 159 acres of upland. Vegetation in these areas consists of degraded remnant prairie, diverse reconstructed prairie, grasslands dominated by smooth brome and/or Kentucky bluegrass, and scattered trees and shrubs, including green ash, bur oak (Quercus macrocarpa), and wild plum (Prunus americana).

2.3 Physical/Geographic Setting and Historic Condition

Union Slough NWR is on the southeastern edge of the Prairie Pothole Region (PPR), which extends from central Iowa through Alberta, Canada (Figure 2-4). The PPR is well known for its importance to breeding waterfowl, and the region is responsible for producing more than 50 percent of the continent’s waterfowl, earning it the nickname “the duck factory of North America.” This portion of the Great Plains, the Northern Tallgrass Prairie, is characterized by a prairie landscape dotted with prairie potholes, which are shallow, depressional wetlands that formed as the result of the Wisconsonian glaciation. The Des Moines Lobe of the Wisconsonian glaciation is the last ice sheet to have covered parts of Iowa. At its maximum extent, the Des Moines Lobe covered approximately 7.6 million acres in north central Iowa (Eilers and Roosa 1994). When the glacier receded, it left a poorly drained landscape that contained more than 3.4 million acres of wetlands (Miller et al. 2012). The glacier receded from the area of the Refuge about 12,000 years ago, making it the youngest landform in the state.

However, as part of a pre-glacial river channel that was not obliterated by the Wisconsonian glaciation, Union Slough is an unusual feature on the landscape. The landform that survived was a long narrow channel that was shut in by high banks and hills. The substrate of Union Slough is blue clay, which is characteristic of the much older Kansas glacial drift (MacBride 1902). Overflow water from Union Slough was able to exit out either the north end or the south end of the slough, and the direction of the flow was often determined by the direction of the wind. The north outlet flowed into the Blue Earth River and proceeded north to the Minnesota River. The south outlet flowed into Buffalo Creek before entering the East Fork of the Des Moines River on

Union Slough National Wildlife Refuge Habitat Management Plan 17 Chapter 2. Background its way south. While all water leaving Union Slough eventually ends up in the Mississippi River, it can take two very different paths to get there.

Prior to European settlement, the landscape around Union Slough was dominated by tallgrass prairie and numerous pothole wetlands (Figure 2-5). The only trees in the immediate area were primarily limited to small forested buffers along streams including the East Fork of the Des Moines River. According to the original surveyor’s notes, Ramsey Township (the north end of the Refuge) was described as treeless with a gently rolling surface with many swamps and marshes, ponds and sloughs. Portland Township (the south end of the Refuge) was described as a gently rolling prairie with numerous small marshes, several of considerable extent (Schiek 1996). The Kossuth County Soil Survey also provides evidence that the area was historically treeless. Soils that developed under some level of tree cover are found only in a few small areas along drainages in the watershed of the East Fork of the Des Moines River (USDA 1983). Disturbances such as fire and grazing prevented the establishment of trees. A rich abundance of wildlife including elk (Cervus canadensis), bison (Bison bison), greater prairie chicken (Tympanuchus cupido), whooping crane (Grus americana), waterfowl, and many grassland and wetland birds thrived under these habitat conditions.

Figure 2-4. Prairie Pothole Region of North America.

Union Slough National Wildlife Refuge Habitat Management Plan 18 Chapter 2. Background

Figure 2-5. Presettlement Vegetation in the Vicinity of Union Slough NWR.

Union Slough NWR is located within the Plains and Prairie Potholes Landscape Conservation Cooperative (LCC, Figure 2-6). LCCs are part of a national initiative to provide scientific and technical support for conservation at "landscape" scales. They support biological planning, conservation design, prioritizing and coordinating research, and designing species inventory and

Union Slough National Wildlife Refuge Habitat Management Plan 19 Chapter 2. Background monitoring programs. The Plains and Prairie Potholes LCC boundary transcends existing regional boundaries and the international border with Canada. The geography includes three main sub- units, the prairie pothole region, northern Great Plains, and the riparian corridors of several major river systems including the Missouri, Yellowstone, and the Red River of the North. Since its inception in 2010, the LCC has provided nearly $3.5 million in funding to bolster the conservation community’s scientific foundation for management of natural resources and the development of tools and frameworks to improve collaboration within the conservation community. As per the Plains and Prairie Potholes LCC’s Annual Report (2012), the key landscape level issues that exist within the LCC are energy development, conversion of native prairie, and wetland drainage. These issues impact the health and productivity of shared natural resources within the LCC landscape and accelerating climate change will only serve to magnify the impacts of these stressors. Unfortunately, both state and federal natural resource managers in Iowa have had little involvement with the Plains and Prairie Potholes LCC to date. Most of the focus has been on the portion of the LCC involving South Dakota and North Dakota. Hopefully in the future, additional LCC resources will be devoted to engaging and supporting natural resource managers in the portion of the LCC in Iowa.

Union Slough National Wildlife Refuge Habitat Management Plan 20 Chapter 2. Background

Figure 2-6. Union Slough NWR within the Plains and Prairie Potholes LCC.

Union Slough National Wildlife Refuge Habitat Management Plan 21 Chapter 2. Background

2.4 Current Natural and Anthropogenic Disturbances

The rich, organic soils found in the PPR of Iowa were formed over thousands of years by the matrix of tallgrass prairie and wetlands that covered the area. As well as creating ideal habitat conditions for a diverse array of grassland and wetland-dependent wildlife, it also produced some of the world’s best soil for agriculture. As European settlers began to understand the agricultural potential of Iowa’s soils, a broad-scale transformation of the prairie landscape was set in motion. Once settlers discovered how to break the prairie sod with the steel moldboard plow, it did not take long to convert most of Iowa’s land area into intensively-managed agricultural land. While the upland prairies were being plowed to make way for crops, the pothole wetlands were being ditched, tiled, and drained at an astonishing rate. Rivers were straightened, ditches were dug, and thousands of miles of drainage tile were installed in an effort to remove water from the land. Ultimately, the vast prairie and wetland complex that made up the PPR of Iowa was converted almost exclusively to an agricultural landscape in less than 100 years (Smith 1990). Today, within the PPR of Iowa, 96 percent of the historic wetlands and 99.9 percent of the historic prairies are gone (Figure 2-7). Lands in the immediate vicinity of the Refuge are no exception to these region-wide trends.

Not surprisingly, the dramatic changes in the landscape since the mid-1800s have led to significant impacts on the native wildlife of the area. Rapid and extensive habitat loss led to the quick extirpation of many species, such as bison, elk, gray wolf (Canis lupus), marbled godwit (Limosa fedoa), whooping crane, and long-billed curlew (Numenius americanus). Other species, such as the greater prairie chicken, actually increased for a short time after settlement. Eventually, as habitat loss continued, the greater prairie chicken also disappeared. Many grassland birds were able to maintain viable populations by their ability to colonize agricultural grasslands that had been converted into haylands or pastures. However, since 1950, the acreage of agricultural grasslands has significantly declined. When the Refuge was established, numerous grasslands were scattered throughout the agricultural landscape surrounding the Refuge. Today, there are a few grasslands located near the Refuge, and most of the Blue Earth River and Des Moines River watersheds are intensively farmed. Ultimately, the Refuge has become an island of habitat in an intensively farmed landscape.

The removal of fire and large herbivores from the landscape combined with the introduction and proliferation of tree groves and shelterbelts has greatly increased the prevalence of woody vegetation in the Iowa PPR. As homesteads and other building sites were added to the landscape, trees were strategically planted for relief from the wind and sun. Although the total area covered by woody vegetation does not amount to a large percentage of the landscape, the high frequency of groves and shelterbelts across the area provides a source of tree seed that can reach nearly all areas of the landscape. The result is that trees are able to quickly become established in areas that were historically treeless.

The alteration of prairie and wetland habitat, including the increased prevalence of trees, has directly impacted habitats within the Refuge. For example, the area near Buffalo Creek and the East fork of the Des Moines River at the south end of the Refuge has changed from grassland to a scrubby forest since the area was settled by Europeans. Since the establishment of the Refuge, staff worked to restore certain elements of ecological integrity that were degraded by the removal and alteration of native plant communities. During years immediately following the Refuge’s establishment, Refuge staff was focused on returning grass to the landscape. Early grassland restoration efforts utilized readily-available species including smooth brome and Kentucky bluegrass, both are cool-season, sod-forming perennial grasses native to Europe. More recently, Refuge staff has focused on restoring the original native tallgrass prairie plant community. Invasive plants such as crown vetch and reed canary grass continue to present challenges to the restoration of the ecological integrity of the Refuge. Management actions such

Union Slough National Wildlife Refuge Habitat Management Plan 22 Chapter 2. Background as properly-timed prescribed fire, prescribed grazing, mowing, haying, tree removal, disking, chemical treatment and reseeding will continue to be used to promote the establishment and long-term sustainability of tallgrass prairie and other native plant communities on the Refuge.

Figure 2-7. 1992 Vegetation in the Vicinity of Union Slough NWR.

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2.5 Current Refuge Conditions and Resources

Soils

According to the Soil Survey of Kossuth County Iowa (USDA 1983), Union Slough NWR is located on a general soil association of Clarion, Storden and Colo soil types. Clarion soils consist of well drained, moderately permeable soils on convex upland knolls, ridges and side slopes. These soils formed in glacial till under a native vegetation of grasses. Slopes range from 2 to 14 percent. Storden soils consist of well drained, moderately permeable soils on convex upland knobs and side slopes. These soils formed in glacial till under a native grassland plant community. Slopes range from 5 to 40 percent. Colo soils consist of poorly drained, moderately permeable soils on bottom land and upland drainage ways. These soils formed in silty alluvium under a native vegetation of water tolerant grasses. Slopes range from 0 to 5 percent.

Topography

Union Slough is a pre-glacial riverbed that forms a connection between the watersheds of the Blue Earth River and the East Fork of the Des Moines River. The many prairie potholes and the poorly developed natural drainage ways in the local landscape are clear indications that Union Slough NWR is located within a geologically young landscape that was created by the Wisconsin glaciation. Mean sea level (MSL) elevations range from approximately 1120 MSL to 1180 MSL in the local vicinity. Refuge topography ranges from large, flat marshy areas to steep side slopes and flat hilltops in refuge uplands.

Hydrology and Water Quality

Extensive agricultural drainage has contributed to increased flow and more frequent flooding in areas adjacent to rivers and streams, which in turn has a strong influence on Refuge water management. The water control structures on Union Slough NWR can only offer limited control of water depth on the Refuge; each of the Refuge Units do not have independent water control. To lower the water in one of the middle units, the water must be lowered in every unit from the target unit to the outlet at either the north or south end of the Refuge. This arrangement makes water level management particularly difficult during extreme wet weather periods. The southern outlet of the Refuge drains into Buffalo Creek, which has a large watershed and is prone to flooding. This situation leads to many occasions where the water in Buffalo Creek is higher than the water in Refuge pools. In these instances, all Refuge pools must drain to the north outlet. Water levels in Units 5, 4, and most of 3 can be managed efficiently with the outlet on the north end of Unit 5. Removing water from Units 1 and 2 is much more efficient when the water can drain to the south outlet at the south end of the A Pool in Unit 1. Units 1 and 2 can also drain to the north, but only after the water depth in these two units gets higher than desired.

The wetlands on Union Slough NWR are greatly influenced by the surrounding watershed. Water quality in Refuge wetlands has deteriorated due to sedimentation and eutrophication caused by runoff from neighboring farm fields. According to an unpublished 1995-1996 U.S. Geological Survey (USGS) study, the mean sediment increase in Refuge pools from 1938 to 1995 was 2.62 feet, or more than 0.5 inches per year. In addition to sedimentation problems, several contaminant studies conducted since the 1990’s have found numerous wetland quality issues including nitrate loading, elevated levels of ammonia, low dissolved oxygen levels, limited benthic macroinvertebrate diversity, limited wetland plant diversity, massive phytoplankton blooms, and elevated selenium levels (Coffey 2000). The source of many of these problems is the effluent of the approximately 70 known drainage tiles that dump into the Refuge. The tile introduces a pathway for excess sediment, nutrients and pesticides to enter the Refuge wetlands. In addition, drainage tile has effectively increased the watershed of Union Slough NWR. The resulting increase in water entering the Refuge has disrupted the natural wet-dry cycles that occurred

Union Slough National Wildlife Refuge Habitat Management Plan 24 Chapter 2. Background historically. The combination of more stable water conditions and the introduction of more sediment, nutrients and pesticides have contributed to dense cattail stands in shallow water areas and wet meadow zones that are dominated by reed canary grass.

Habitat Types

Union Slough NWR contains three broad habitat types: prairie/grassland, wetland, and river bottomland. All of these communities have been significantly altered by the changes in the regional and local landscape since the area was settled in the mid-1800s.

Prairie/Grassland

There are approximately 1,590 acres of prairies and grasslands on Union Slough NWR, not including grass-dominated areas found in the river bottomlands as discussed below. Prairies include high-quality and degraded tallgrass prairie remnants, low-diversity native grass plantings, and higher-diversity planted prairie restoration areas. Grassland refers to areas that were historically planted with or have been invaded by introduced cool-season grasses, primarily smooth brome and Kentucky bluegrass. Many Refuge prairies and grasslands contain a mix of species that form a continuum from mostly native prairie species to mostly introduced species, including smooth brome and Kentucky bluegrass. The categorization and mapping of these different grassland types has not been completed, primarily because many areas contain a mix of native and introduced species, which makes determining the boundaries between different prairie/grassland types very difficult.

Prairies and grasslands on the Refuge grasslands have undergone significant change from their pre-settlement condition. Many prairies were plowed and converted to cropland before the establishment of the Refuge. Remaining tallgrass prairie remnants are extremely rare, and most in the PPR and in the immediate vicinity of the Refuge are small, isolated, and greatly influenced by fragmentation and disturbances associated with the surrounding cropland. Specifically, the movement of sediment, nutrients, and agricultural chemicals from adjacent crop fields to Refuge lands has reduced plant diversity and has lowered the overall ecological integrity of prairies and grasslands on the Refuge. These alterations have also provided openings for invasive plants like Canada thistle (Cirsium arvense), smooth brome, yellow and white sweet clover (Melilotus officinalis and M. alba.), crown vetch, wild parsnip (Pastinaca sativa), and reed canary grass to gain a foothold. Indeed, these invasive plants have proven to be strong competitors in Refuge prairies and grasslands.

Wetland

There are approximately 1,208 acres of wetland located on Union Slough NWR, comprised of 1,200 acres of marsh (including main Refuge pools, several small potholes, and numerous created sediment catch basins) and eight acres of flooded gravel pits. For the purposes of this HMP, wetlands do not refer to any stream or floodplain wetland areas that are included in the river bottomland classification as described below.

Past efforts to drain Union Slough and the surrounding landscape have permanently altered the original character of wetlands within the Refuge. The ditch dug to drain Union Slough in the early 1900s is still visible today in many parts of the Refuge, and the spoil piles that were created are prominent features in several marsh areas. Close to 70 known agricultural drainage tiles convey water from neighboring cropland into the Refuge. In addition to the extra water received on the Refuge, these tile lines also add unwanted sediment, nutrients, and pesticides to the marsh (Coffey 2000). Willows (Salix spp.), cottonwoods (Populus spp.) and reed canary grass have taken advantage of the hydrological and physical disturbances to gain a foothold in marshes throughout the Refuge.

Union Slough National Wildlife Refuge Habitat Management Plan 25 Chapter 2. Background

River Bottomland

There are approximately 536 acres of river bottomland found on Union Slough NWR. For the purposes of this HMP, river bottomland includes the stream channels of Buffalo Creek and the East Fork of the Des Moines River, as well as many old oxbows and other low spots that frequently flood. In addition, the historic grasslands of the non-depressional areas of the floodplain are also included in this community type.

Historically, these river bottomlands and floodplains were primarily covered with prairie/grassland, according to historical data including the original land surveyor notes, old aerial photos, and soil survey data (Schiek 1996). However, large portions of the floodplain of Buffalo Creek and the East Fork of the Des Moines River have recently undergone significant tree invasion, primarily by green ash and silver maple. The spread of trees into this area began as part of landscape alterations caused by the conversion of surrounding areas to agriculture, but the rate of invasion has increased since the 1970s. Trees compete with herbaceous prairie/grassland vegetation for light, nutrients, and water, although some stands of rice cutgrass, river bulrush, smartweed, and other native herbaceous vegetation still persist under the tree canopy as evidence of historical species composition. In addition to habitat encroachment, the spread of woody species has effectively fragmented grasslands in some areas, which has made those areas less attractive to birds that require large tracts of uninterrupted grasslands for nesting. Trees also attract predators and nest parasites like the brown-headed cowbird (Molothrus ater) (Johnson and Temple 1990).

Rare Plant Species and Exemplary Natural Communities

Prairie bush clover is a federally threatened prairie legume found only in the tallgrass prairie region of Iowa, Minnesota, Illinois, and Wisconsin. In addition to its federal status, prairie bush clover is listed as threatened in Iowa, and as endangered or threatened in each of the three other states where it occurs. The preferred habitat of prairie bush clover is gentle, usually north-facing slopes comprised of fine silty loam, fine sandy loam, or clay loam soils. Prairie bush clover was found on one of the high quality prairie remnants that exist on Union Slough NWR in the late summer of 2000. It is quite possible that additional colonies of prairie bush clover may exist on other high-quality prairie remnants on the Refuge, but exhaustive botanical surveys have not been conducted of all these areas. In addition to prairie bush clover, the prairie remnants on the Refuge are home to a high diversity of tallgrass prairie species that have virtually vanished from the national and regional landscape.

Current Wildlife

Birds

Migratory birds are the primary focus of the management at Union Slough NWR. More than 240 species of birds, including 27 waterfowl species, have been documented on the Refuge. Common nesting waterfowl species include mallard (Anas platyrhynchos), blue-winged teal (Anas discors), Canada goose (Branta canadensis), trumpeter swan (Cygnus buccinator), and wood duck (Aix sponsa). During migration, shorebird numbers can exceed 10,000 birds. Common shorebird species include killdeer (Charadrius vociferus), lesser yellowlegs (Tringa flavipes), greater yellowlegs (Tringa melanoleuca), pectoral sandpiper (Calidris melanotos), and least sandpiper (Calidris minutilla). Other birds commonly seen on the Refuge include pied-billed grebe (Podilymbus podiceps), great blue heron (Ardea herodias), yellow-headed blackbird (Xanthocephalus xanthocephalus), red-winged blackbird (Agelaius phoeniceus), common yellowthroat (Geothlypis trichas), bobolink (Dolichonyx oryzivorus), dickcissel (Spiza americana), song sparrow (Melospiza melodia), sedge wren (Cistothorus platensis), red-tailed hawk (Buteo jamaicensis), and bald eagle (Haliaeetus leucocephalus).

Union Slough National Wildlife Refuge Habitat Management Plan 26 Chapter 2. Background

Mammals

The Refuge is home to many mammal species. Common species include white-tailed deer (Odocoileus virginianus), mink (Mustela vision), muskrat (Ondatra zibethicus), raccoon (Procyon lotor), opossum (Didelphis virginiana), striped skunk (Mephitis mephitis), red fox (Vulpes vulpes), coyote (Canis latrans), plains pocket gopher (Geomys bursarius), eastern cottontail (Sylvilagus floridanus), meadow vole (Microtus pennsylvanicus), meadow jumping mouse (Zapus hudsonius), and thirteen-lined ground squirrel (Ictidomys tridecemlineatus). Many of these species are bird nest predators and have great influence on the level of nesting success on the Refuge. Although comprehensive mammal surveys on the Refuge have not been completed, there is anecdotal evidence that red fox numbers have been reduced while coyote numbers have increased over the last 25 years.

Reptiles and Amphibians

Reptile and amphibian species known to occur on Union Slough NWR include painted turtle (Chrysemys picta picta), snapping turtle (Chelydra serpentina), Blanding’s turtle (Emydoidea blandingii), Northern prairie skink (Plestiodon septentrionalis), eastern garter snake (Thamnophis sirtalis sirtalis), smooth green snake (Opheodrys vernalis), tiger salamander (Ambystoma tigrinum), northern leopard frog (Lithobates pipiens) , and American toad (Bufo americanus). The Blanding’s turtle is listed as threatened in Iowa. Overall, reptile and amphibian species and populations have not been thoroughly inventoried on the Refuge.

Invertebrates

Invertebrates have not been well inventoried on the Refuge, and very little information exists regarding historical or current invertebrate taxa on the Refuge or in the surrounding area. The Iowa Multiple Species Inventory and Monitoring (MSIM) Plan is a standardized statewide survey of Iowa’s wildlife with a goal of providing basic inventory of wildlife species in Iowa. The Iowa Department of Natural Resources (IDNR) conducts the MSIM Plan in selected locations across the state each year. In 2012, one of the properties surveyed was Union Slough NWR. The result of that survey effort was a list of dragonflies, damselflies, and butterflies observed on the Refuge. The draft list included 22 species of dragonflies and damselflies and 25 species of butterflies, including the regal fritillary (Speyeria idalia), which is a species of special concern in Iowa.

Invasive Fish

The introduction of non-native invasive fish, particularly the common carp (Cyprinus carpio), has negatively influenced water quality in Refuge wetlands. Common carp frequently enter Refuge pools, uprooting vegetation and stirring up sediment. The end result is lower water quality and reduced wetland plant production and associated invertebrate production.

Invasive Plants

Invasive plant species alter a landscape by outcompeting native species, altering the physical structure of a community, and/or by altering the nutrient and chemical cycling of a system. Invasive species often can form dense monocultures, reducing both botanical diversity and the quality of wildlife habitat. Though most invasive species are introduced from another area, native species can also be considered to be invasive when their presence in new landscape positions results in similar negative effects. The species described below are the most problematic for management at Union Slough NWR.

Crown vetch is an exotic perennial legume that is highly invasive in prairies and grasslands. It spreads rapidly both by seed and vegetatively through its multi-branched creeping root system. Crown vetch can develop dense stands that crowd out native plants. Crown vetch has invaded large portions of the Refuge, including many of the remnant prairie areas. It poses a legitimate

Union Slough National Wildlife Refuge Habitat Management Plan 27 Chapter 2. Background threat to the known colonies of the federally-threatened prairie bush clover that occur on the Refuge.

Reed canary grass is an aggressive, cool-season perennial grass that invades and dominates a variety of wetland types, including the marshes on the Refuge. Disturbances such as erosion, sedimentation, nutrient enrichment, and any activity that exposes bare ground tend to facilitate the spread of reed canary grass. Streams, wetlands, and ditch networks facilitate the dispersal of this species, particularly during periods of flooding when seeds and vegetative fragments float in the water and can be transported great distances. Reed canary grass has formed thick stands that ring most of the wetlands on the Refuge. It is also a dominant plant in the river bottomlands and floodplains of the streams and ditches, as well as in some upland areas. Mechanical and chemical management options are limited on the Refuge by standing water and/or wet ground conditions.

Two very similar species, white sweet clover and yellow sweet clover, are exotic, biennial legumes that compete for resources with native plants. The early growth of sweet clover enables it to overtop and stunt many native prairie species, thus reducing plant species diversity. Many upland sites on Union Slough NWR are heavily invaded by white and yellow sweet clover. Prescribed fire, an important prairie/grassland management tool, can increase sweet clover populations on the Refuge, if not properly used. It is possible to achieve some reduction in sweet clover by burning the same area in consecutive years. The timing of the fire in the second year is critical in reducing sweet clover. The second year fire must be late enough in the spring so that second year sweet clover plants have emerged and are at a susceptible stage, but early enough that the fire intensity is sufficient to kill the sweet clover. Achieving this balance has proven difficult because of annual variability in vegetation and weather conditions.

Wild parsnip is an exotic plant that belongs to the Apiaceae or carrot family. Flowering occurs after two, three, or more years, after which the plant dies (a monocarpic perennial). It can cause severe skin irritation to people that have contacted sap from broken leaves or stems. Wild parsnip invades ditches, grasslands, and other open areas, and occurs as scattered plants in several areas of the Refuge. It can be controlled with well-timed mowing or herbicide applications.

Smooth brome and Kentucky bluegrass are exotic, perennial, cool season sod-forming grasses introduced from Europe. They frequently invade native grassland, where they compete with warm season species because of their early-season growth and aggressive spread. Smooth brome and Kentucky bluegrass occur throughout the upland areas of the Refuge. Burning in the late spring or chemical application before the emergence of warm season plants in the early spring can help push the competitive advantage back in favor of native vegetation.

Canada thistle is an exotic, creeping perennial plant that can spread quickly and form monotypic stands. This plant is considered a noxious weed in Iowa and usually requires some type of control effort to keep populations from spreading. Appropriate herbicide applications are often effective. On the Refuge, mowing has also proved effective in areas with newly planted native seedings. Following mowing, competition provided by the growing native plant seedlings will often suppress the Canada thistle after 3-5 years.

Cattail, including broad-leaf cattail (Typha latifolia), narrow-leaf cattail (T. angustifolia) and hybrid cattail (T. x glauca) are perennial, grass-like wetland plants that are an important component of the wetland habitats at Union Slough NWR. Although broad-leaf cattail is native to the area and seldom becomes invasive, narrow-leaf and hybrid cattails are exotic and often form large, dense, monotypic stands that prevent the growth of other plants. Large stands of cattail occur in the Refuge’s C Pool. Chemical treatment and prescribed fire can be used to open up cattail- dominated areas and allow other plant species to persist.

Union Slough National Wildlife Refuge Habitat Management Plan 28 Chapter 2. Background

Common reed (Phragmites australis) is a tall, perennial grass that can reach heights of 15 feet. There are two subspecies of common reed that are morphologically very similar, but have somewhat different growth forms. The native subspecies (P. australis subsp. americanus) typically occurs in loose patches in higher-quality plant communities. The invasive, exotic subspecies (P. australis subsp. australis) tends to form dense, monotypic stands that crowd out native plants. Union Slough NWR has several scattered patches of common reed, but it is unclear whether these are of the native or exotic subspecies. At least one of these patches occurs in the marsh near the Refuge office and appears to be a dense monotypic stand that has expanded over recent years. The populations of common reed on the Refuge need to be evaluated more closely and treated if appropriate.

Woody vegetation, both native and exotic, can be considered invasive when it enters into prairie/grassland areas. Many prairie areas of the Refuge have been invaded by woody vegetation. The south portion of the Refuge near Buffalo Creek and the East Fork of the Des Moines River contains the Refuge’s most dramatic change from the historic condition in terms of woody plants. Successional invasion by species such as green ash, silver maple, and various willows have caused this area to be transformed from floodplain grassland to a plant community similar to a bottomland forest. Returning this area to grassland will require many years of sustained management.

Research and Monitoring

Staff at Union Slough NWR currently conducts waterfowl surveys from ice-out to June 1 and from September 1 to ice-up. Biweekly counts are conducted form June 1 through August 31. These surveys allow Refuge staff to track waterfowl use of the Refuge throughout the year as well as to help determine the impact of habitat management actions on bird populations and habitat use. Raptors, shorebirds, marshbirds, and waterbirds are also counted during these surveys.

Refuge staff also conducts a waterfowl breeding pair survey and a waterfowl brood survey each year. These surveys are conducted to obtain a rough estimate of waterfowl production on the Refuge.

Refuge staff are currently working to design a vegetation monitoring protocol for both upland and wetland areas of Union Slough NWR. In 2013, all Refuge pools were surveyed using a random meander method in order to begin generating a list of wetland plants that occur on the Refuge.

Union Slough National Wildlife Refuge Habitat Management Plan 29 Chapter 3. Resources of Concern

Chapter 3. Resources of Concern

Bobolink, a priority resource of concern at Union Slough NWR. Photo Credit: USFWS Midwest Region

3.1 Introduction 3.2 Identification of Refuge Resources of Concern 3.3 Biological Integrity, Diversity, and Environmental Health 3.4 Priority Refuge Resources of Concern 3.5 Priority Habitat Types and Associated Priority Species 3.6 Conflicting Habitat Needs 3.7 Adaptive Management

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3.1 Introduction

Defining Resources of Concern

Resources of Concern (ROCs) are the focal point of a Habitat Management Plan (HMP). The HMP policy (620 FW 1) defines ROCs as

All plant and/or animal species, species groups, or communities specifically identified in refuge purpose(s), System mission, or international, national, regional, state, or ecosystem conservation plans or acts. For example, waterfowl and shorebirds are a resource of concern on a refuge whose purpose is to protect "migrating waterfowl and shorebirds.” Federal or State threatened and endangered species on that same refuge are also a resource of concern under terms of the respective endangered species acts.

The U.S. Fish and Wildlife Service (USFWS) is entrusted by Congress to conserve and protect migratory birds, federally-listed threatened and endangered species, inter-jurisdictional fish, and certain marine mammals (trust species) for the benefit of the American people. Each refuge also has its own specified purpose(s) for which it was created that guides its management goals and objectives. Within these purposes, refuges support other elements of biological diversity such as locally rare plant, invertebrate, and vertebrate species, natural communities, and the ecological processes that contribute to the biological integrity and environmental health at the refuge, ecosystem, and broader scales (601 FW 3).

Importance of ROCs to Refuge Activities

Identifying ROCs allows us to identify refuge-scale management objectives aimed at maintaining, increasing, and/or improving the habitats required by trust resources and populations identified in the Refuge purpose. The Resources of Concern (ROC) identification process facilitates a targeted approach to identifying priority areas and/or gaps in management that may require additional resources, such as information (data collection and monitoring) or staff and equipment. Species respond to habitat management differently and therefore identifying ROCs allows us to focus management activities at an appropriate level that yields the greatest benefit to trust resources, complimenting biological integrity, diversity and environmental health (BIDEH) and the Refuge purpose.

The first step of developing a focused habitat management strategy is to define a refuge’s comprehensive list of ROCs within the context of the mandates, purposes, policies, and regional and national plans that apply to that refuge.

3.2 Identification of Refuge Resources of Concern

International, national, and regional conservation plans relevant to Union Slough National Wildlife Refuge (NWR) were identified and used in ROC selection. A comprehensive list of species known to use the Refuge was compiled by season and relative abundance (Appendix A). Each species’ conservation significance was then quantified as the number of conservation plans that included that species. Significant natural communities were also considered as potential priority ROCs. The comprehensive list of ROCs was narrowed down further by selecting resources most likely to represent a suite of habitat needs for other species (i.e., surrogate species) using the process is later defined in section 3.4.1. We refer to this subset of ROCs as priority ROCs.

Refuge Purpose and Resources of Concern

As discussed in Chapter 1, the Refuge was established in 1938 primarily to assist with the production and management of waterfowl in the Mississippi Flyway. This HMP covers 3,334 acres of fee title land distributed across three major habitat types: approximately 1,208 acres of wetland (comprised of 1200

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acres of marsh and 8 acres of inundated gravel pits), 1,590 acres of prairies and grasslands, and 536 acres of river bottomlands. The stated purpose for the Refuge is to be “… a refuge and breeding ground for migratory birds and other wildlife” (Executive Order 7976, Sept. 14, 1938). The mission of the Refuge is to preserve, restore, and manage lands and waters sufficient in size and character to meet the needs of migratory birds and other wildlife for the continued benefit of the American people (USFWS 1996).

Refuge System and USFWS Resources of Concern

USFWS Trust Resources

While the designated purpose is the foremost determinant of a particular refuge’s management, managing trust resources also is a priority for all Service lands. Trust resources relevant to Union Slough NWR include migratory birds and threatened and endangered species, which are discussed below.

Migratory Birds

A list of all species of migratory birds protected by the Migratory Bird Treaty Act (16 U.S.C. 703–711) and subject to the regulations on migratory birds is contained in subchapter B of title 50 CFR §10.13. The USFWS Division of Migratory Bird Management also maintains lists of priority bird species of concern at national, regional, and eco-regional (Bird Conservation Region) scales. The primary sources of information the Refuge used to identify potential migratory bird species of concern include:

• State and Federal Listed Species • USFWS Birds of Management Concern, Region 3 (USFWS 2011b) • USFWS Birds of Conservation Concern, Bird Conservation Region (BCR) 11 (USFWS 2008) • USFWS Migratory Bird Program Strategic Plan (USFWS 2004a) • USFWS North American Waterfowl Management Plan (USFWS 2004b) • Prairie Pothole Joint Venture Implementation Plan (Ringleman 2005) • Partners in Flight Northern Tallgrass Prairie Conservation Plan (Fitzgerald et al. 1998) • Iowa State Wildlife Action Plan (Zohrer et al. 2005) • Natureserve Global and State Conservation Rankings • Status and Trend Information for Refuge bird surveys and regional assessments

Threatened and Endangered Species

The Endangered Species Act (16 U.S.C. 1531–1544, December 28, 1973, as amended 1976-1982, 1984 and 1988) states in Sec. 8A.(a) that:

“The Secretary of the Interior… is designated as the Management Authority and the Scientific Authority for purposes of the Convention and the respective functions of each such Authority shall be carried out through the United States Fish and Wildlife Service.”

The act also requires all Federal departments and agencies to conserve threatened and endangered species and to utilize their authorities in furtherance of the purposes of this Act.

Federal threatened or endangered species were identified for inclusion in this HMP by reviewing the Federal threatened and endangered species list and relevant recovery plans for listed species (see http://ecos.fws.gov/ecos/indexPublic.do).

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3.3 Biological Integrity, Diversity, and Environmental Health

Defining BIDEH

The Refuge Improvement Act states that, in administering the System, the Service shall “ensure that the biological integrity, diversity, and environmental health of the System are maintained…” The Service’s policy (USFWS 2003a) discusses the role of biological diversity, integrity, and environmental health (commonly referred to by its acronym BIDEH). It also provides managers with an evaluation process to analyze their refuge and recommend the best management direction to prevent further degradation of environmental conditions, and where appropriate and in concert with refuge purposes and System mission, restore lost or severely degraded components (601 FW 3). The Service defines BIDEH as follows:

• Biological Diversity - The variety of life and its processes, including the variety of living organisms, the genetic differences between them, and the communities and ecosystems in which they occur.

• Biological Integrity - Biotic composition, structure, and functioning at genetic, organism, and community levels comparable with historic conditions, including the natural biological processes that shape genomes, organisms, and communities.

• Environmental Health - Composition, structure, and functioning of soil, water, air, and other abiotic features comparable with historic conditions, including the natural abiotic processes that shape the environment.

Identifying BIDEH within the Refuge

The Service manages for priority species with habitat needs that exist along a continuum of vegetation structures and hydrologic regimes within habitat types present on the Refuge. The Service has reviewed historic information of the area in and around the Refuge, taken an inventory of its current conditions and management strategies, assessed the restoration potential of habitats, established priority resources, and reviewed the overall purpose of Union Slough NWR. To assess historic, current, and future potential conservation status for the Refuge, the Service also reviewed relevant literature describing requirements of selected priority species and ecosystem processes that regulate natural communities. The following information sources were used to describe baseline environmental, abiotic, and biotic conditions within the Refuge:

• Reports and associated data on site history and capabilities (e.g., Refuge surveys and research reports) • Maps of existing landscape conditions displaying watershed boundaries, habitat connectivity or isolation, and land use conditions and ownership surrounding the Refuge • Maps and/or information about the existing and pre-Refuge (1938) vegetation types • Soil Surveys of Kossuth County (USDA 1983) • Global/regional trends in climate change and water quality • Iowa Department of Natural Resources information on rare, declining, threatened, or endangered species • Iowa State Wildlife Action Plan (Zohrer et al. 2005) • Status and trend information for potential species of concern as documented in regional/state assessments and reports • Previous habitat classifications and designations developed by Refuge staff and the Comprehensive Management Plan (CMP) (USFWS 1996) • Minnesota’s Native Plant Community Classification (Aaseng et al. 2011)

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Based on a review of the existing and historical data, the HMP planning team developed a list of habitat types that contain elements of BIDEH to evaluate processes that influence the ecological and biological integrity of habitat types within the Refuge (see Table 3-1). For the purposes of this HMP, three broad habitat types were determined to be present on the Refuge: prairie/grassland, wetland, and river bottomland. Table 3-1 also provides a crosswalk between these three broad habitat types and both National Vegetation Classification System (NVCS) associations and Minnesota Native Plant Community classification schemes. Both the river bottomland and the existing gravel pits on the Refuge represent habitats that provide some ecological and/or wildlife value, although, they are not representative of the desired condition or completely representative of BIDEH on the Refuge. Limitations to BIDEH for both those habitats are discussed in chapter 4.

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Table 3-1. Summary of Habitats that Represent Existing BIDEH on Union Slough NWR

Broad MN Native NVCS Alliance Natural Limiting Habitat Plant 2 Populations and Habitat Attributes 1 Classification Processes Factors/Stressors Type Community Grass-dominated herbaceous communities on level to steeply sloping sites with droughty soils. Patchy to Fire suppression. continuous mid-height and shortgrass species are Smooth sumac prominent; little bluestem (Schizachyrium scoparium) Little Bluestem- (Rhus glabra) and may dominate. Also side-oats grama (Bouteloua Dry conditions, Southern Dry Porcupine eastern red cedar curtipendula), prairie dropseed (Sporobolus spp.), lower soil fertility, Prairie Grass Dry- (Juniperus porcupine grass (Stipa spartea), big bluestem recurring fire. mesic Prairie virginiana) (Andropogon gerardii), and Canada wild rye (Elymus invasion. Heavy canadensis). Graminoid cover is patchy to continuous grazing. (50–100% cover). Sparse (5–50%) variable forbs. Sparse (< 5%) shrubs; trees absent or occasional. Grass-dominated but forb-rich herbaceous communities Conversion to row on loam soils on level to gently rolling sites. Uniform, crops. Fire Prairie/Grassland predominantly tallgrass with some mid-height grass. suppression. Northern Mesic Graminoid cover is usually continuous, dominated by big Loam soils allow Kentucky bluegrass Southern Tallgrass bluestem, prairie dropseed, and Indian grass moisture retention; and smooth brome Mesic Prairie Prairie (Sorghastrum nutans). Forbs include goldenrods recurring fire. invasion. Heavy (Solidago spp.), asters (Symphyotrichum spp.), grazing. Pocket coneflower (Echinacea spp.) and lead plant (Amorpha gophers promote canescens). brome.

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Broad MN Native NVCS Alliance Natural Limiting Habitat Plant 2 Populations and Habitat Attributes 1 Classification Processes Factors/Stressors Type Community Grass-dominated, forb-rich herbaceous community on Flooded for brief poorly drained loam soils formed in lacustrine periods at most; sediments, unsorted glacial till, or outwash deposits. upper part of Graminoid cover is usually continuous (75–100%). Tall rooting zone is not Fire suppression, grasses with some low grasses and sedges (Carex saturated for most Northern heavy grazing. Southern Wet spp.), including cordgrass (Spartina spp.), switchgrass of growing Cordgrass Wet Ditching, tiling, Prairie (Panicum virgatum), and narrow reedgrass season, but Prairie draining for (Calamagrostis stricta). Sparse to patchy forbs (5–50% saturation persists agriculture. cover) include Canada goldenrod (Solidago in lower zone for canadensis), sunflowers (Helianthus spp.), blazing star much of season. (Liatris spp.), asters, and dogbane (Apocynum spp.). Episodic grazing Shrubs absent or sparse (5–25% cover); trees absent. or recurring fire. A shallow depression with surface water present for a few weeks in the spring and after heavy rain events. Isolation from Occupies the central portion of shallow basins and a groundwater flow; band around deeper basins. Open wetlands dominated Non-native species runoff and rain

by dense cover of sedges in small, closed, shallow invasion, Southern inundations then basins isolated from groundwater inputs. Continuous particularly reed Basin Wet Awned Sedge evaporation graminoid cover (75–100%) includes sedges, cordgrass, canary grass Meadow/ Wet Meadow causes increased spikerush (Eleocharis spp.). Absent to sparse forbs following alteration Wetland Carr salinity; frequent (<25%) including smartweed, cattail, bugleweed of hydrology. Fire fire causes (Lycopus spp.), swamp milkweed (Asclepias incarnata). suppression. reduction of Shrub cover is typically sparse (< 5%) and includes shrubs. slender willow (Salix petiolaris) and pussy willow (S. discolor).

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Broad MN Native NVCS Alliance Natural Limiting Habitat Plant 2 Populations and Habitat Attributes 1 Classification Processes Factors/Stressors Type Community Found in the portions of shallow basins where surface water persists in the spring through early summer before Spring inundation Ditching, draining, drying out in the late summer and fall. Mineral or by snowmelt and tiling, grazing, shallow muck soils on calcareous drift. Open wetlands rains is short-lived agricultural nutrient Prairie Wet Bluejoint - dominated by a dense cover of graminoids (50–100% with shallow inputs. Alterations Meadow/ Woolly Sedge cover) in shallow swales. Continuous graminoid cover depths, down- in hydrology Carr Wet Meadow of narrow reedgrass, prairie cordgrass, woolly sedge gradient drainage; resulting in invasion (Carex pellita). Forb cover (< 50%) of panicled aster frequent fire by reed canary (Symphyotrichum laeve), water smartweed (Polygonum causes reduction grass. amphibium), sunflowers, mint (Mentha arvensis), and of shrubs. Joe-pye weed (Eupatorium spp.). Sparse shrubs. Sometimes classified as semi-permanent ponds or Alteration of water lakes. Present in ponds, along lakeshores and stream table due to human borders. Surface water is present throughout most of the activity; Standing water Prairie Bulrush - growing season. Emergent marsh communities typically succession. present most of Bulrush- Cattail - dominated by bulrush (Scirpus spp.), bur-reed Siltation and year; stable water Arrowhead Burreed (Sparganium spp.), arrowhead (Sagittaria spp.), or sedimentation of table; protected Marsh Shallow Marsh spikerush. Submergent aquatic vegetation includes wet areas. from wave action. water smartweed, coontail (Ceratophyllum demersum), Invasion by narrow- pondweeds (Stuckenia spp.), milfoil (Myriophyllum spp.), leaved or hybrid naiad (Najas spp.). cattails. Surface water is permanently present with fairly stable Water table water levels. Emergent marsh dominated by dense alteration (human clonal single-species patches interspersed with open

Standing water or beaver activity; water. Substrate covered with plant litter. Floating and Midwest Mixed present most of succession). Prairie Mixed submerged vegetation includes water smartweed, Emergent Deep year; stable water Siltation and Cattail Marsh duckweed (Lemna spp.), bladderwort (Utricularia spp.) Marsh table; protected sediment filling of Wetland and water lily (Nymphaea spp.). Graminoids includes from wave action. wet areas, narrow- bulrush and sedges. Dominated by cattail; other forbs leaved or hybrid may be tufted loosestrife (Lysimachia thyrsiflora), cattails. horsetail (Equisetum spp.). Shrubs absent.

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Broad MN Native NVCS Alliance Natural Limiting Habitat Plant 2 Populations and Habitat Attributes 1 Classification Processes Factors/Stressors Type Community Dynamic equilibrium of many factors: variation in water Loss of dynamic depths, water equilibrium and Interdependent features that indicate health of a stream velocities, degradation due to are grouped into the following five components: shape, streambed urbanization and flow, connectivity, biology, and water quality. Streams substrates, and changes in land are complex networks of terrestrial and aquatic types of cover; use; dams, ditching communities and their floodplains provide diverse connectivity to and drainage for n/a n/a habitats including uplands, riparian zones

Bottomland other water agriculture. Loss (streambanks), floodplain forests, marshes, fens, oxbow bodies. Healthy of vegetation along lakes, riffles, and pools. The diverse habitats and their floodplains streambanks; River plant and animal species are important to maintaining combine to create stream bank healthy ecosystems. Species include terrestrial and 3 diverse habitats, erosion, sediment aquatic plants, fish, mussels, and aquatic invertebrates. which encourage loads and excess diverse wildlife nutrients. 3 and plant communities to thrive. 3

1 Aaseng et al. 2011 2 NatureServe 2014 3 MN DNR 2014a

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Maintaining and Restoring BIDEH

As discussed in Chapter 2, Union Slough NWR’s BIDEH is significantly influenced by the intensive agriculture that exists in the landscape surrounding the Refuge. Most of these external influences are outside the direct control of the Refuge staff. At the core, intensive agriculture has impacted the natural hydrology of the watershed surrounding the Refuge and has often made the management of water levels within the Refuge difficult. Additionally, sediments, nutrients, and contaminants associated with the surrounding agriculture, and disturbed hydrology has impacted BIDEH on the Refuge. Other impacts to the Refuge’s BIDEH include invasive species that have degraded native plant and wildlife communities. Also, altered hydrology and the cultural practices of promoting tree establishment have increased the abundance of trees and shrubs in some areas of the Refuge, reducing the quality of natural communities that were historically treeless.

Management objectives and strategies to maintain and restore BIDEH will be discussed in detail in Chapters 4 and 5. In general, management actions will continue to improve degraded natural communities toward a state where native species are more dominant. The area with heavy tree cover at the south end of the Refuge is perhaps the most degraded area on the Refuge. It is highly unlikely that this area can be returned to its native grassland condition during the 15 year life of this plan. The desired outcome to maintain and enhance BIDEH for this area would be, at a minimum, to prevent the expansion of woody vegetation. Ideally, the amount of native grassland habitat would be expanded in the south end of the Refuge during the life of this HMP.

This HMP has amended the original goals and refined some of the objectives contained in the CMP in order to be in compliance with BIDEH policy (610 FW 3) and to encourage the effective protection and restoration of BIDEH on the Refuge. By maintaining existing BIDEH and sustainably managing it over the life of this HMP, we will support the Refuge purpose and habitat needs of priority resources and other benefitting species. These changes and the rationale behind them are outlined in Chapter 4.

3.4 Priority Refuge Resources of Concern

The potential ROC table (Appendix A) contains a comprehensive list of species that occur on or near the Refuge. The Service selected priority species using the Service’s Identifying Refuge Resources of Concern Handbook (the Handbook; Paveglio and Taylor 2010), as well as aspects of Strategic Habitat Conservation (SHC), which is an iterative process developed by the Service to support strategic decisions on habitat conservation for species on landscape-level scales (USFWS 2008).

To assist refuge managers and planners with identifying priority ROCs for management and monitoring and completing the selection process outlined in the Handbook, Cardno JFNew developed the Resources of Concern Selection Tool for America’s Refuges (ROCSTAR). The ROCSTAR tool allows refuge staff to review the applicable filters required when considering priority ROC selection. It also provides a decision support framework that allows users to compare various resources and their ability to address the selection considerations outlined in the Handbook (Paveglio and Taylor 2010). The tool results in a series of resource scorings sorted by habitat type. Based on the scoring results, the planning team can then make an informed decision on the number and type of priority ROCs to select for each habitat type managed on the Refuge. The results of the ROCSTAR scoring evaluation are included in Appendix B.

The goal of this process is to select refuge-specific priority ROCs that can be used as indicators of the success of overall habitat management and whether benefits are being afforded to other species utilizing the same habitat types. The Handbook guides the selection of priority ROCs by considering which resources best address the following considerations:

• Relevance to Legal Mandates

• Management Significance

• Ecological Significance

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Relevant Legal Mandates

Candidate priority resources were evaluated for their ability to be managed in order to fulfill the Refuge purpose and associated Service policies and mandates.

• Contribution to Refuge purpose – Achieving Refuge purposes and managing for trust resources as well as BIDEH can be addressed through habitat requirements of focal species, i.e., species that may represent guilds that are associated with important attributes or conditions within habitat types. The use of focal species is particularly valuable in addressing Service trust resources such as migratory birds. By selecting focal species, the Refuge can document our Refuge-specific contribution to migratory bird conservation.

• Contribution to listed species – One federally-listed species, prairie bush clover, is known to occur on Union Slough NWR. Prairie bush clover is a federally threatened prairie plant found only in the tallgrass prairie region of four Midwestern states: Iowa, Illinois, Minnesota, and Wisconsin. Prior to 2000, the plant had not been documented on the Refuge, and it may occur in other prairie remnants on the Refuge that have not been thoroughly surveyed. The presence of prairie bush clover indicates that the Refuge contains tallgrass prairie habitat of relatively high quality. Thus, addressing prairie bush clover in this HMP is one way that the Refuge can address the important Service mandate to protect listed species.

• Contribution to Refuge System – The conservation of priority species within the Refuge plays an important role in supporting the mission of the National Wildlife Refuge System (NWRS). Certain priority species can be used as a measure of management progress. Those species can be used to develop an inventory and monitoring plan (IMP) in order to evaluate management and communicate the success and challenges of management with others. In doing so, the Refuge will aid in providing long-term support for the NWRS.

Management Significance

Candidate priority resources were evaluated for their management significance to the Refuge. A species was considered significant to management on the Refuge if it had the following characteristics: 1) species have a direct application to key management decisions or effectiveness of past management activities, 2) species are reliant on habitat management to provide suitable or improved conditions, 3) management and protection of the species or its habitat is recognized as important (i.e. presence in regional conservation plans and lists noted previously) by managers, researchers, policy makers and the public. Evaluating management significance is important because data on the species and its habitats can help inform management decisions and progress toward Refuge goals. Specifically,

• Habitat requirements of priority species – Habitat suitability and availability may limit the capability of the Refuge to support or manage for a priority species of concern. The following species- specific factors were evaluated:

• Historic habitat use and abundance on the Refuge • Connectedness and species utilization of habitat types • Environmental conditions including soils, hydrology, disturbance patterns, contaminants, predation, and invasive species • Specific life history needs, such as habitat needs for breeding, migrating, and overwintering stages of avian species.

• Habitat management for selected priority species – Observations and institutional knowledge of the Refuge personnel and other Service staff were used to determine the feasibility for the Refuge to support a particular species throughout specific seasons (e.g., breeding, migration, overwintering).

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• The need for management and protection of the priority species is recognized – Chapter 1 highlighted various national, regional, and state conservation plans used to identify conservation priorities for the Refuge. Species on the comprehensive ROC list were initially ranked based on the sum of conservation plans in which they were found. Ranked species were then filtered by relative seasonal abundance on the Refuge, where applicable. In doing so, some species that ranked high on conservation plans, but were only incidental on the Refuge, were not included in the priority species selection since they presumably could not be effectively managed for.

• Contribution to inventory and monitoring – Candidate priority species were evaluated for their potential contribution to the future development of the Refuge’s inventory and monitoring program. Priority species must be able to provide indicators of habitat management by responding to our management actions through increased use, improved breeding, presence/absence, or by another measure. We reviewed each candidate for its ability to be monitored, amount of existing data specific to the station, and the likelihood of it being affected through management.

Ecological Significance

Candidate priority resources were evaluated through a series of planning team meetings, literature reviews, and an interagency partner review for their ecological significance to the Refuge. Ecological significance was defined as a species 1) having a strong, defensible link to overall ecological function of the landscape or be strongly associated with a critical resource of the Refuge, 2) sensitive to larger landscape or habitat changes so that it can act as an indicator of potential change, and 3) status of the species or its habitat is representative of other priority species, ecological processes or biological organizations. Evaluating the ecological significance of candidate priority species helps ensure that management and monitoring activities associated with priority species and their habitats contribute to the BIDEH of the Refuge. Priority resources can be used as an indicator of BIDEH based on their presence, absence, abundance, or relative well-being in a given habitat niche. In doing so, it serves as a marker of overall health of its required habitat type.

Using these criteria, Refuge staff refined the list of potential ROCs during HMP development based on continued review of the criteria previously described. From the process, ten priority species, one guild, and one priority habitat were selected for Union Slough NWR. In doing so, we removed some candidate priority species that duplicated the habitat requirements and potential management response. These species were removed because the selected priority species had some measure of preference for management and monitoring purposes. This preference was sometimes the result of available datasets for the Refuge and range or specificity of habitat requirements. In addition, the monarch butterfly was added as a priority species due to its recent, significant population decline. This brings the total to eleven priority species, one guild, and one priority habitat that were selected for Union Slough NWR. A list of these species and their general habitat requirements can be found in Table 3-2. Discussion of the selection considerations for each priority ROC can be found following the table.

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Table 3-2. Habitat Requirements for Union Slough NWR Priority ROCs.

Key Habitat Relationships Priority Resource Vegetative Composition Vegetative Structure Patch Size Special Considerations Habitat Patches of >100 ha <1 Dry grasslands with low to moderate A mosaic of adjacent grasslands of km apart or large forb cover, low woody cover, Benefits from preventing different heights, undisturbed (>1000 ha) contiguous Upland sandpiper moderate grass cover, moderate to the invasion of woody grassland, grazed lands, and grassland with a mosaic high litter cover, and little bare species. hayed fields. of burn frequencies in ground (Houston et al. 2011). blocks of >60 ha. Tallgrass and shortgrass Grasshopper Open grassland with patchy bare prairie/grassland species (Vickery 30 to 100 ha. sparrow ground; minimal shrub component. 1996).

Tallgrass or mixed-grass prairie, or Fields comprised of a mixture of Low tolerance for woody old fields >8 years and converted grasses and forbs with little woody Bobolink Fields ≥ 30 ha. species in or surrounding from cropland to perennial grassland vegetation. Tolerates some shrubs grassland. cover (Martin and Gavin 1995). up to 1m tall.

Nesting habitat highly Graminoids with medium shrub susceptible to drying or Upright sedges and fine grasses Sedge wren density; avoids sparse, flooded, Not available. flooding and transitory; (Herkert et al. 2001). open, and cattail vegetation. low site tenacity and fidelity.

Prairie/Grassland Federally threatened; Persists on lightly grazed prairie Loss of habitat due to Tallgrass prairie species; moderately Prairie bush clover pastures, haylands, and prairie Not applicable. development, invasion of damp to dry soils (USFWS 2009b). remnants. woody and invasive species. Grasslands containing critical milkweed plants for larval food and Open fields and meadows that Available milkweed Monarch egg-laying, as well as abundant include milkweed, various nectar Not applicable plants for larval food and nectar producing forbs for adult food producing forbs and grasses egg laying is critical sources. Native upland and wet prairie; larvae feed only on violets (Viola spp.), Protection of prairie Regal fritillary especially prairie violet (V. Restricted to native prairie habitats. Not available. remnants critical. pedatifida) and bird's-foot violet (V. pedata) (MN DNR 2014b).

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Key Habitat Relationships Priority Resource Vegetative Composition Vegetative Structure Patch Size Special Considerations Habitat

Native herbaceous vegetation Native prairie Native upland and wet prairie Contains rare and unique made up of varying heights and Not applicable. remnants remnants. plant and animal species. densities.

Waterfowl - shallow water breeders:

Mallard Blue-winged teal Northern pintail High density stands of short to Northern shoveler moderate grasses within 150m of Not available. None. Shallow water Seasonal and semi-permanent water for nest sites; shallow water, migrants and shallow wetlands with much farm fields used for foraging. occasional breeders: emergent and submergent vegetation; farm fields and cropland Gadwall for foraging (Lokemon et al. 1990, American wigeon Austin and Miller 1995, Johnson Green-winged teal 1995, Ryder and Alisauskas 1995,

Wetland Dubowy 1996, Leschack et al. 1997, Austin et al. 1998, Mowbray 1999, Mowbray et al. 2000, Drilling and McKinney 2002, Rohwer et al. 2002, Roy et al. 2012). Waterfowl - shallow water migrants:

Emergent wetlands, shallow water Ross’s goose Not available. None. and farm fields used for foraging. Snow goose Lesser scaup Ring-necked duck

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Key Habitat Relationships Priority Resource Vegetative Composition Vegetative Structure Patch Size Special Considerations Habitat

Waterfowl - open Marshes with muskrat houses or Marshes with hardstem bulrush water and marsh other elevated nesting sites; easy Semi-permanent or (Schoenoplectus acutus) or cattail; breeders: access to water in proximity to permanent agricultural fields and cropland for None. abundant food source such as low impoundments of 1 to foraging (Mowbray et al. 2002, Canada goose grasses, sedges, and adjacent 1,500 ha. Mitchell and Eichholz 2010). Trumpeter swan farm fields.

Waterfowl - open Shallow ponds, lakes, and riverine water and marsh marshes; abundance of sago migrants: Areas of open water or open marsh pondweed rhizomes and tubers for resting in proximity to shallow Not available. None. preferred; also harvested agricultural Tundra swan water margins for foraging. fields of cereal grain (Ely and Dzubin Greater white- 1994, Limpert and Earnst 1994) fronted goose

Waterfowl - migrant and occasional breeders:

Redhead Ruddy duck Large slow-moving rivers, lakes, Canvasback open marshes; dense beds of vegetation of all kinds (Gauthier Large water bodies with shallower

Waterfowl - deep 1993, Eadie et al. 1995, Mallory and Not available. None. water feeding areas. water and marsh Metz 1999, Titman 1999, Brua 2002, migrants: Mowbray 2002, Woodin and Michot 2002) Common merganser Wetland Bufflehead Common goldeneye Red-breasted merganser

Marshes with dense cattail, sedges, Interspersion of fine and robust flatsedges (Cyperus spp.), bur-reed, emergent vegetation and water; Occurs more commonly Sora None. and bulrushes (Melvin and Gibbs wetland edges, adjacent upland in wetlands of > 5 ha. 2012). fields.

Union Slough National Wildlife Refuge Habitat Management Plan 44 Chapter 3. Resources of Concern

Key Habitat Relationships Priority Resource Vegetative Composition Vegetative Structure Patch Size Special Considerations Habitat

Vegetation/water Shallow wetlands with tall, interspersion in spatially emergent vegetation and water complex pattern Marshes with dense cattail, sedges American bittern depths <10 cm; complex Wetlands > 10 ha. increases breeding (Lowther et al. 2009). interspersion of vegetation and diversity and density of water (Lowther et al. 2009). marshbirds including bitterns.

Shallow flooded habitat with Mudflats, pools, shores, fields and adjacent open mudflats or Lesser yellowlegs seasonal wetlands (Tibbits and Not applicable. None. seasonally flooded farm fields; soft Moskoff 2014). substrates.

Open woodlands with grassland Forest edges, open woods with Red-headed understory in upland or lowland savanna-like grasslands, especially Not available. None. woodpecker including river bottoms (Smith et al. areas with large dead or dying 2000). trees.

Flooded shrubland, water-tolerant

Waterfowl - wooded Bottomland trees, small areas of open water, Living or dead deciduous trees with wetland breeders: emergent plants such as bur-reed, cavities; scrub/shrub wetland with Promote and maintain arrow arum (Peltandra virginica), overhead cover of downed timber; River Not available. trees with natural cavities Wood duck arrowhead, and smartweed, (Dugger dense stands of emergent plants; where appropriate. Hooded merganser et al. 2009, Hepp and Bellrose mixture of shallow freshwater 2013). wetland types in close proximity.

Union Slough National Wildlife Refuge Habitat Management Plan 45 Chapter 3. Resources of Concern

Prairie/Grassland

Grasshopper sparrow (Ammodramus savannarum), upland sandpiper (Bartramia longicauda), bobolink (Dolichonyx oryzivorus) and sedge wren (Cistothorus platensis) are priority resources representing the guild of grassland birds. There are sufficient populations of these species on the Refuge to warrant management, and their habitat requirements cover a wide range of grassland conditions.

The monarch (Danaus plexippus) has experienced severe, recent population declines. As a result, it is the current focus of much scientific investigation. Monarchs are commonly seen at Union Slough NWR as the Refuge lies within the heart of their breeding range.

The regal fritillary (Speyeria idalia) is listed as a species of special concern in Iowa. This butterfly relies on tallgrass prairie that contains various species of violets as larval food plants. The regal fritillary is known to occur on Union Slough NWR and may be an indicator that the Refuge contains prairie remnants that are of high ecological quality and provide adequate habitat for prairie-dependent invertebrates.

Prairie bush clover (Lespedeza leptostachya) is a federally-threatened plant found only in the tallgrass prairie region of Iowa, Minnesota, Illinois, and Wisconsin. In addition to its federal status, prairie bush clover is listed as endangered or threatened in each of the four states where it occurs (threatened in Iowa). A population of this plant is found on one of the high quality prairie remnants that exist on Union Slough NWR.

Native prairie remnants are rare in the Prairie Pothole Region (PPR), which has lost more than 99.9 percent of the historic tallgrass prairie. These remnants provide critical habitat for a diverse assemblage of plants and animals, and are also important as living examples of the historic vegetation.

Wetland

Waterfowl are a high priority resource for Union Slough NWR. Important species of waterfowl on the Refuge include mallard (Anas platyrhynchos), wood duck (Aix sponsa), blue-winged teal (Anas discors), northern pintail (Anas acuta), green-winged teal (Anas crecca), northern shoveler (Anas clypeata), gadwall (Anas strepera), American widgeon (Anas americana), lesser scaup (Aythya affinis), ring-necked duck (Aythya collaris), redhead (Aythya americana), ruddy duck (Oxyura jamaicensis), canvasback (Aythya valisineria), bufflehead (Bucephala albeola), common goldeneye (Bucephala clangula), hooded merganser (Lophodytes cucullatus), common merganser (Mergus merganser), red-breasted merganser (Mergus serrator), Ross’s goose (Chen rossii), snow goose (Chen caerulescens), Canada goose (Branta canadensis), greater white-fronted goose (Anser albifrons), trumpeter swan (Cygnus buccinator), and tundra swan (Cygnus columbianus). The executive order that established Union Slough NWR states that the Refuge purpose is primarily to assist with the production and management of waterfowl in the Mississippi Flyway. In addition to wetland habitats, many species of waterfowl also use grasslands, streams, and riparian zones. The range of habitat needs of waterfowl also cover the habitat needs for a wide variety of other species.

The sora (Porzana carolina) is a secretive waterbird of freshwater marshes that often remains hidden in dense wetland vegetation. This species is listed as a priority species for Partners in Flight Bird Conservation Plan for the Northern Tallgrass Prairie. It commonly occurs at Union Slough NWR during the breeding season.

The American bittern (Botaurus lentiginosus) prefers large wetlands with tall, dense vegetation that are surrounded by upland grassland habitat. This species is listed as a bird of conservation concern in BCR 11 and is a Resource Conservation Priority in the Mississippi headwaters/tallgrass prairie portion of USFWS Region 3. This species has been documented nesting at Union Slough NWR.

The lesser yellowlegs (Tringa flavipes) commonly utilizes Union Slough NWR during spring and fall migration periods. Annual flights of several thousand birds are common. Significantly higher numbers can be seen during some years. The lesser yellowlegs is listed as a species of greatest conservation need in

Union Slough National Wildlife Refuge Habitat Management Plan 46 Chapter 3. Resources of Concern

Iowa. Providing for the migratory habitat needs of lesser yellowlegs also benefits many other species of shorebirds and waterbirds.

River Bottomland

The red-headed woodpecker (Melanerpes erythrocephalus) inhabits areas with relatively low tree stem density, preferring scattered trees and forest edges with grasslands. This habitat condition exists on the southern end of the Refuge, and will continue to be enhanced as trees are removed during the transition to more open grassland conditions. The red-headed woodpecker is listed as a species of greatest conservation need in Iowa’s State Wildlife Action Plan. It is also identified in several other regional plans as a species of concern. The red-headed woodpecker is a confirmed nester on Union Slough NWR.

Some waterfowl species, particularly wood duck and hooded merganser, rely on cavities in mature trees for nesting. They utilize herbaceous marsh habitats for foraging, but prefer marshes with woody vegetation nearby. As such, they indicate the presence of a matrix of forested and emergent wetlands on the Refuge.

Priority Resources and Refuge BIDEH

Table 3-3 summarizes how priority resources, where applicable, likely use habitats within the Refuge and the surrounding landscape based on a literature review, professional judgment, and management experience. Several priority species use more than one habitat type at one or more times of the year, thus emphasizing the importance of integrated habitat management. Certain priority species use the Refuge for breeding, foraging, and/or migratory stopover purposes, thus their populations may fluctuate depending on the time of year.

Management activities associated with a given priority resource or species has direct and indirect benefits for other species that have similar habitat requirements. Table 3-3 lists the group or guild of species each priority resource represents. In many cases, activities to benefit the priority species will likely result in benefits for other species that are conservation priorities. The species listed in the “Other Benefitting Resources” column in Table 3-3 is not an all-inclusive list. The species listed were derived from reviewing the previously mentioned regional plans, Refuge staff and researcher observations, and selecting species of conservation concern that are rated as relatively high priority species across the region.

Union Slough National Wildlife Refuge Habitat Management Plan 47 Chapter 3. Resources of Concern

Table 3-3. Priority ROCs and Other Benefiting Species at Union Slough NWR.

Life History Other Benefitting Priority Resource Habitat Structure Requirement Resources Habitat

Mosaic of adjacent undisturbed grasslands of different Migration, nesting, brood Upland sandpiper heights. rearing, foraging

Open grassland with patchy bare ground; minimal shrub Migration, nesting, brood Grasshopper sparrow component. rearing, foraging

Migration, nesting, brood Bobolink Mixture of grasses and forbs with little woody vegetation. rearing, foraging Common nighthawk Dickcissel

Migration, nesting, brood Henslow’s sparrow Sedge wren Dense upright sedges or sedges and other fine grasses. rearing, foraging Le Conte’s sparrow Nelson’s sharp-tailed sparrow Vesper sparrow Lightly grazed prairie pastures, haylands, and prairie Clay-colored sparrow Prairie bush-clover Whole life remnants. Field sparrow Eastern meadowlark Northern harrier Migration, egg-laying, larval Open fields and meadows that include milkweed, various Swainson’s hawkArogos Monarch foraging, pupa development,

Prairies and Grasslands nectar producing forbs and grasses. Skipper adult foraging Poweshiek skipperling Short-eared Owl

Regal fritillary Native prairie habitats. Annual life cycle

Native prairie remnant Diverse mixture of forbs and grasses. Not applicable

Union Slough National Wildlife Refuge Habitat Management Plan 48 Chapter 3. Resources of Concern

Life History Other Benefitting Priority Resource Habitat Structure Requirement Resources Habitat Waterfowl - shallow water breeders:

Mallard Blue-winged teal Northern pintail Northern shoveler Migration, nesting, brood Shallow water and wetlands with adjacent grasslands. Le Conte’s sparrow rearing, foraging Shallow water migrants Nelson’s sharp-tailed and occasional breeders: Yellow rail Northern harrier Gadwall Wilson’s phalarope American widgeon Buff-breasted sandpiper Green-winged teal Mulberry Wing Broad-winged Skipper Waterfowl - shallow water Short-eared Owl migrants:

Ross’s goose Shallow water and wetlands. Migration, foraging Snow goose Wetlands Lesser scaup Ring-necked duck

Waterfowl - open water and marsh breeders: Migration, nesting, brood Open water, marsh and elevated nesting sites. Canada goose rearing, foraging Black tern Trumpeter swan Forster’s tern Common moorhen Waterfowl - open water American white pelican and marsh migrants: Bald eagle Osprey Tundra swan Open marsh with proximity to shallow feeding areas. Migration, foraging Greater white-fronted goose

Union Slough National Wildlife Refuge Habitat Management Plan 49 Chapter 3. Resources of Concern

Life History Other Benefitting Priority Resource Habitat Structure Requirement Resources Habitat Waterfowl - migrant and occasional breeders:

Redhead Ruddy duck Black tern Canvasback Forster’s tern Common moorhen Waterfowl - deep water Large water bodies with shallower water feeding areas. Migration American white pelican and marsh migrants: Bald eagle Osprey Common merganser Bufflehead Common goldeneye Red-breasted merganser

Migration, nesting, brood

Sora Shallow water, dense vegetation. Least bittern rearing, foraging Yellow-crowned night heron Black-crowned night heron King rail Wetlands Migration, nesting, brood Yellow rail American bittern Shallow water, dense vegetation. rearing, foraging Whooping crane Sandhill crane

Greater yellowlegs Solitary sandpiper Buff-breasted sandpiper American avocet Lesser yellowlegs Sparse vegetation, soft substrate for probing. Migration, foraging Short-billed dowitcher Hudsonian godwit Marbled godwit Piping plover

Union Slough National Wildlife Refuge Habitat Management Plan 50 Chapter 3. Resources of Concern

Life History Other Benefitting Priority Resource Habitat Structure Requirement Resources Habitat

Orchard oriole Red-headed woodpecker Migration, nesting, brood Open forests or forest edges with savanna-like grasslands. Loggerhead shrike rearing, foraging

Northern flicker

Red-shouldered hawk Waterfowl - wooded Rusty blackbird wetland breeders: Peregrine falcon

River Bottomlands Dense emergent wetland and flooded woodland with Migration, nesting, brood Prothonotary warbler Wood duck dead/dying trees with cavities. rearing, foraging Brown creeper Hooded merganser Louisiana waterthrush Osprey Bald eagle

Union Slough National Wildlife Refuge Habitat Management Plan 51 Chapter 3. Resources of Concern

3.5 Priority Habitat Types and Associated Priority Species

Management activities on the Refuge often focus on restoring, managing, or maintaining habitats or habitat conditions to benefit a suite of priority species, plants, or animals associated with a particular habitat. The priority habitat types of the Refuge were identified based on information compiled including historic conditions, current vegetation, site capability, and conservation needs of other benefitting species (Table 3-4).

Because all potential management activities cannot be concurrently implemented every year, the Refuge has adopted a strategy of focusing management efforts on one quarter of the Refuge each year on a rotating basis, as described in Chapters 4 and 5. However, because different habitats on the Refuge require different management strategies and/or levels of effort, habitat types within the lands managed in any given year have been prioritized based on the following ranking factors:

• Where management actions would provide the greatest conservation benefit to identified priority species,

• Current habitat conditions and the urgency of needs for active management, and

• The ability of a habitat type to be positively affected through management.

Although some habitats are ranked as Priority 2, this should not be interpreted as meaning that they do not provide valuable habitat to a variety of species or contribute to Refuge BIDEH. These habitats may not require active management, may represent areas where there are limited management capabilities, or under current conditions, may exhibit a limited response to habitat management. If conditions change in the future, Priority 2 habitats may be elevated to Priority 1 status or vice versa during the scheduled HMP review. Table 3-4 lists the Refuge’s priority habitats and the limiting factors/threats for each.

Table 3-4. Priority Habitats and Their Potential Limiting Factors on Union Slough NWR.

Habitat Rationale for Designation Limiting Factors/Threats

Priority 1 Habitats

Invasive plants and fish. Increased water inputs from Supports the Refuge purpose. Provides Wetland (Marsh) watershed. Eutrophication, migratory and breeding habitat for waterfowl. sedimentation, and contamination from watershed. Supports the Refuge purpose. Provides migratory and breeding habitat for waterfowl Invasive plant species; loss of fire Prairie/Grassland and grassland birds. Important to supporting to reduce woody vegetation. and maintaining the BIDEH of the Refuge.

Priority 2 Habitats

Woody vegetation is more prevalent today Modified hydrology; loss of fire to than prior to Service ownership. reduce woody vegetation. River Bottomland Removal/thinning of trees will require long- Invasive plant species; term, sustained effort. lack of tree species diversity. Artificial habitat on the Refuge left over from activities prior to Service ownership. Invasive plants and fish. Wetland (Gravel Pit) Seasonally important to migrating waterfowl

late in the fall/early winter season. No water management capacity.

Union Slough National Wildlife Refuge Habitat Management Plan 52 Chapter 3. Resources of Concern

3.6 Conflicting Habitat Needs

Given the diversity of goals, purposes, mandates, and conservation priorities for the NWRS, it is not uncommon to have conflicting management priorities at a refuge. Balancing the types and proportion of habitats (and their management) requires special consideration and a process for determining the best course of action. Union Slough NWR contains habitat and management decisions that require such consideration. For example, some waterfowl and grassland bird species prefer different vegetation structure and composition from each other. Annually treating approximately one quarter of the upland acres on the Refuge with one or more management techniques will help to provide the diversity of habitat structure different wildlife species require.

3.7 Adaptive Management

Priority species and their respective habitat attributes were used to develop habitat objectives (Chapter 4). Habitat management objectives must be achievable, and factors may reduce or eliminate the ability of the Service to achieve objectives. Although these factors were considered during the development of management objectives, conditions may change over the next 15 years and beyond, requiring the use of adaptive management principles as outlined in Chapter 1.

The planning team identified specific management areas where we anticipate an ongoing need for adaptive management to maximize the Refuge’s biological benefits. These considerations may require an accelerated iteration and alteration of management actions (Steps 9 and 6, respectively, of the adaptive management guidance, Chapter 1) outside of the anticipated 5-year HMP review. These include, but are not limited to:

• Increased amount of water entering the Refuge from drain tiles throughout the watershed and impacts to the Refuge habitats due to water quality (sedimentation and chemicals transported from agricultural land uses).

• Significant changes in the abundance of crown vetch, reed canary grass, or other invasive species

• Implementation of treating all Refuge acres at least once every four years with one of the following management actions: haying, grazing, prescribed fire, mowing, tree removal, or invasive species control as identified in Chapters 4 and 5.

Union Slough National Wildlife Refuge Habitat Management Plan 53 Chapter 4. Habitat Goals and Objectives

Chapter 4. Habitat Goals and Objectives

Blue-winged teal. Photo credit: USFWS Midwest Region

4.1 Background 4.2 Habitat Goals and Objectives

Union Slough National Wildlife Refuge Habitat Management Plan 54 Chapter 4. Habitat Goals and Objectives

4.1 Background

The goals in the Comprehensive Management Plan (CMP) represent broad statements of the desired future conditions of the Refuge (602 FW 1.6). The objectives are concise ideas that specify what needs to be achieved, how much needs to be achieved, when and where it needs to be achieved, and who is responsible for the work. Strategies, which are specific actions, tools, or techniques required to achieve objectives, are discussed in chapter 5.

During the development of this Habitat Management Plan (HMP), Refuge staff reviewed the existing goals and objectives of the CMP to determine if they were still representative of existing refuge conditions and desired future management. After detailed review and discussion, staff determined that the objectives outlined in the CMP could be restructured to make them conform to the Service’s Specific, Measureable, Achievable, Results-oriented, Time fixed (SMART) criteria and benefit more plant and wildlife species. The objectives developed during the HMP process will provide a framework for Refuge habitat management until a new CCP is developed. For each habitat objective, rationale is provided in order to summarize the scientific information and professional judgment used to formulate each objective.

One habitat objective was developed for each of the main habitat types on the Refuge: prairie/grassland, marsh, river bottomland, and gravel pits. As discussed in Chapter 2, “wetlands” is used as a general term to encompass both marshes and gravel pits on the Refuge. However, gravel pits are an artificial habitat, present limited opportunities for active management, and therefore are distinctive from marshes in terms of management needs and capacity. Therefore, for the purposes of Chapters 4 and 5 of this HMP, we consider marsh and gravel pits to be separate habitat types within the broader classification of wetlands, which was used as a more inclusive term in Chapters 1 – 3.

Objectives and strategies were developed from the approach that Refuge management will focus management efforts on one quarter of the Refuge (approximately 833 acres) each year on a rotating basis. Figure 4-1 illustrates the locations of all the Refuge subunits. Table 4-1 shows the proposed four year cycle for management treatments on all subunits of Union Slough NWR. This approach allows for all land on the Refuge to receive some aspect of management at least once every four years, reducing the potential for any one area of the Refuge to become severely degraded. This approach also reflects the Refuge’s emphasis that all habitat types on the Refuge are worthy of at least some management, including both high quality and severely degraded areas. It should be noted that all marsh pools are managed annually with water level manipulations. The proposed water levels are set each year in the annual water management plan.

Union Slough National Wildlife Refuge Habitat Management Plan 55

Chapter 4. Habitat Goals and Objectives

Union Slough 2016 Subunits 2017 Subunits 2018 Subunits 2019 Subunits NWR Unit Managed Managed Managed Managed

Buffalo Creek 25 26 none 24 Unit

Unit 1 23 22 21 20

Unit 2 16 15, 17 18 19

Unit 3 14 11 12 13

Unit 4 10 7 8 9

Unit 5 6 4 none 5

Schwob Marsh none 1 3 2 Unit

4.2 Habitat Goals and Objectives

REFUGE HABITAT GOAL:

Protect, restore and manage habitat on the Refuge and encourage good land stewardship within the Refuge watershed with an increased emphasis on restoring and preserving a community of life typical of the northern tallgrass prairie/prairie pothole ecosystem.

Objective 1 – Prairie/Grassland

Over the life of the HMP, sustain and enhance a minimum of 1,590 acres of prairie and other grassland habitats across the Refuge to provide breeding, foraging, rearing, and migratory stopover needs for Refuge priority resources such as grassland-dependent wildlife including mallard, blue-winged teal, upland sandpiper, grasshopper sparrow, bobolink, monarch, and regal fritillary, while also providing for the full life cycle requirements of prairie bush clover. To meet this objective:

1. All grasslands will sustain a total vegetated cover of greater than 90 percent perennial herbaceous species, in which the forb component is between 5 and 50 percent.

2. Vegetation will be enhanced to promote a dominance of native species such as big bluestem, little bluestem, Indian grass, Canada wild rye, porcupine grass, as well as a

Union Slough National Wildlife Refuge Habitat Management Plan 57 Chapter 4. Habitat Goals and Objectives

diverse forb community that includes asters, coneflower, lead plant, and other native prairie species.

3. Cover of invasive, exotic species will be less than 10 percent across managed prairies and grasslands.

4. Invasive woody vegetation will be less than 10 percent across managed prairies and grasslands.

5. Reconstruct prairie on low diversity stands of introduced grasses (smooth brome, Kentucky bluegrass, reed canary grass) on up to 20 Refuge acres per year. Ideally, a 50:50 grass to forb ratio will be used, but actual mix will be determined by budget and seed availability constraints.

Rationale

The Refuge falls within the Bird Conservation Region (BCR) 11 Prairie Pothole region (PPR) and the Prairie Pothole Joint Venture (PPJV) region. In the late 1880s, prairie habitats were converted to farmland due to the nutrient- rich, organic soils on which they occurred. The loss of prairie/grassland remains ongoing, particularly with the demand for row crops for food and energy consumption increasing in recent decades. Less than one percent of the original prairie habitat remains in the prairie pothole portion of the state according to Cowardin et al. (1995) and Noss et al. (1995), and less than 0.1 percent (or less than 30,000 acres) of the original prairie habitats may remain statewide (IDNR 2012). The scarcity of these habitats across the region provides significant justification for protecting and managing prairies and grasslands on the Refuge.

Approximately 21.3 million acres of grasslands (including native prairie remnants) were identified across the prairie pothole region, according to the PPJV Implementation Plan (Ringleman 2005). That plan also identified priority grasslands as “grassland with patch sizes no less than 55 acres in size that are accessible to over 25 duck pairs per square mile.” According to these criteria, 11.56 million acres have been designated as priority grasslands throughout the PPR by the PPJV. Of these, approximately 1.16 million acres are currently protected by fee title acquisitions and perpetual grassland easements, which include grasslands at Union Slough National Wildlife Refuge (NWR).

The Refuge contains approximately 1,590 acres of prairie/grassland habitat, consisting of remnant prairie, reconstructed prairie, Kentucky bluegrass-dominated grasslands, and smooth brome-dominated grasslands. As discussed in Chapter 2, because these prairie/grasslands are often intermixed on the Refuge, determining the exact acreage of each grassland type is difficult. However, a rough approximation is that 25% of the grasslands on the Refuge are remnant prairie, 30% are reconstructed prairie, and 45% are Kentucky bluegrass-dominated grasslands, smooth brome-dominated grasslands, or contain a mixture of Kentucky bluegrass, smooth brome, and/or other introduced grasses.

The Refuge contains several areas with remnant prairie, which range in quality from relatively pristine to severely degraded. Because they contain elements of the original landscape, remnant prairies have a higher management priority than all other prairie/grassland types on the Refuge. Remnant prairies, particularly those of higher quality, are used as reference ecosystems, or blueprints, for prairie reconstructions conducted on the Refuge and within the Wetland Management District. Because of their rarity, remnant prairies also provide important learning opportunities for Refuge staff, outside researchers, and members of the public, because we have relatively little information available regarding remnant prairies and how these dynamic ecosystems have persisted over time.

On the Refuge, reconstructed prairies are lands where the original plant community has been severely disturbed or destroyed, primarily by agricultural activities, and subsequently planted with

Union Slough National Wildlife Refuge Habitat Management Plan 58 Chapter 4. Habitat Goals and Objectives an assemblage of native prairie species. The species composition of reconstructed prairies is typically designed to mimic remnant prairies in and around the Refuge and Wetland Management District. Prairies on the Refuge have been and will continue to be reconstructed using native seed collected from remnant prairies and other prairie restorations. Depending on the project, remnant prairies on the Refuge provide approximately 75-100 percent of the seed origin used in reconstructed prairies.

A diverse seed mix is typically used to encourage native plant species to utilize as many resources and niche spaces as possible in order to reduce the invasion of undesirable species. Planting a diverse mix of species that can tolerate a wide range of environmental conditions ensures that the site will have the best opportunity to establish a dominance of native plants (Tilman and Downing 1994). Also, reconstructed prairies with a high diversity of forb and grass species provide the greatest benefit to the most species of wildlife, by providing a phenological range of emergence, bloom period, and seed maturity that makes a variety of resources available to wildlife throughout the growing season. For example, the monarch butterfly (Danaus plexippus) relies solely on milkweed species (Asclepias spp.) during critical periods of its life cycle (NatureServe 2014). Although prairie milkweed (A. sullivantii) and butterfly milkweed (A. tuberosa) begin to bloom around the same time, butterfly milkweed is typically more abundant later in the growing season than prairie milkweed, thus increasing availability of milkweed over time for use by monarch butterflies. Likewise, the regal fritillary relies solely on violets such as bird-foot violet and prairie violet during the larval stage (MNDNR 2014). Without violets as part of the prairie flora, regal fritillary would not exist on the Refuge. Also, many grassland-dependent and upland-nesting waterfowl require a diverse, complex vegetation structure (Winter et al. 2005, Quamen 2007). Prairie reconstructions that incorporate a diversity of forbs and grasses, therefore, contribute the most to maintaining and restoring biological integrity, diversity, and environmental health (BIDEH) on the Refuge. Ideally, a 50:50 grass to forb ratio would be used, but actual mix is determined by budget and seed availability constraints.

Most of the heavily degraded upland grassland areas on the Refuge are dominated by smooth brome or Kentucky bluegrass, two exotic cool-season species that were once widely planted in the area. Reed canary grass often becomes dominant as these areas transition towards the wetland edge. One of the primary functions of Union Slough NWR is to contribute to waterfowl production in the PPR. Degraded grasslands dominated by smooth brome and/or Kentucky bluegrass provide some level of nesting and/or foraging habitat to Refuge ROCs such as mallard, gadwall, blue-winged teal, and Canada goose (Burgess 1969, Duebbert and Lokemoen 1977, Cowardin et. al. 1985, Lokemoen et al. 1990). Overall, however, the Refuge’s smooth brome/Kentucky bluegrass-dominated grasslands are nearly, if not completely, monocultures that have limited overall habitat value as compared to native prairies. Wildlife species benefit from a more varied, diverse, and heterogeneous composition and structure for a variety of reasons, as discussed above. Over time, the desired outcome for grasslands on the Refuge is to reduce the total acreage of smooth brome- or Kentucky bluegrass-dominated grasslands by replacing those grasses with a variety of native prairie species in order to improve ecological integrity and provide greater habitat resources for wildlife. Therefore, on an annual basis, the Refuge will convert up to 20 acres of Kentucky bluegrass/smooth brome dominated grasslands to a diverse mix of native prairie species.

Union Slough NWR currently does not have a farming program. However, in some cases annual browse crops such as oats, wheat, rye, millet, etc. may be planted by Refuge staff and/or partners such as the Kossuth County Conservation Board to assist in preparation for seeding diverse native plant species. These reconstruction plots typically would be 20 acres or less in size. The seed used for these crops would not be genetically-modified or treated with pesticides or fungicides. These crops may incidentally be used as green browse by some species, but the primary purpose is to provide preparation for restoration of native perennial habitat. A Refuge farming plan involving cooperators, genetically-modified crops, etc. was completed in 2014 (USFWS), but is not being implemented at this time. The use of crops as a land management tool supports the biological purposes and management strategies of the Refuge and will adhere

Union Slough National Wildlife Refuge Habitat Management Plan 59 Chapter 4. Habitat Goals and Objectives to all regional and national policies and guidance, such as USFWS Region 3 Pesticide Use Policy, Region 3 Farm Program Guidance and the U. S. Fish and Wildlife Service’s Midwest Region Environmental Assessment for row crop farming and the use of genetically-modified, glyphosate-tolerant (GMGT) corn and soybeans on refuge land. Any expansion of farming with cooperators, additional crop types, or significant addition of acreage will require a new farming plan, site specific NEPA compliance and an updated Compatibility Determination.

Invasive species are a significant threat to the prairie/grassland-dependent ROCs on the Refuge, and they warrant active management in order to protect existing prairies and improve degraded grasslands. In addition to smooth brome, Kentucky bluegrass, and reed canary grass, several other invasive species, including sweet clover, Canada thistle, wild parsnip, and crown vetch are well-established in prairie/grassland habitats. Crown vetch has been particularly difficult to control where it occurs with the federally-threatened prairie bush clover. Crown vetch and prairie bush clover are both legumes, and thus many of the mechanical and chemical treatments intended to reduce crown vetch also act similarly on prairie bush clover. Thus, alternative treatments may need to be considered and implemented in the fight to control crown vetch. The Service’s Endangered Species Program is in the process of evaluating whether prairie bush clover will become a federally-endangered species due to continued habitat loss and degradation. Listing as an endangered species would not change the Refuge’s management to protect and enhance prairie bush clover populations on the Refuge.

According to early land surveys, the area now occupied by the Refuge was historically nearly treeless and was composed primarily of wet prairies, dry prairies, and marsh. Woody encroachment on prairies and grassland areas provides habitat for avian predators, and grassland birds have been shown to avoid areas adjacent to woody habitats solely in order to avoid conflicts with predators (Grant et al. 2004, Graves et. al. 2010, Ellison et. al. 2013). Also, prescribed fire, which is used as a management tool in many prairie/grassland areas on the Refuge, does not carry well through areas of dense woody vegetation, limiting the effectiveness of that management strategy.

Therefore, a primary focus of prairie/grassland management on the Refuge is to reduce existing woody species cover and prevent any additional expansion of trees and shrubs into prairie/grassland areas (USFWS 2003b). However, some limited woody vegetation – particularly shrubs including New Jersey tea (Ceanothus americanus), wild plum, and lead plant – is desired in some instances because it was historically present on the Refuge and provides habitat for grassland bird species that prefer or tolerate some shrub cover. Additional details on management of prairie/grassland habitat techniques to reduce both invasive species and woody vegetation will be provided in Chapter 5. The management to reduce woody vegetation requires a significant amount of Refuge time, staff, and resources on an annual basis.

Objective 2 – Marsh

Over the life of the HMP, annually sustain or enhance a minimum of 1,200 acres of marsh habitat across all Refuge units and provide breeding and migratory stopover for Refuge priority resources such as waterfowl including mallard, blue-winged teal, trumpeter swan, wood duck, and lesser scaup, as well as other migratory birds such as lesser yellowlegs, sora, sedge wren, and American bittern. Marsh habitat will have the following conditions:

1. Between March and November each year, provide between 0 and 240 acres of water depths ranging from 0 (mudflat) to 4 inches deep, between 120 and 720 acres of water

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depths ranging from 4 to 24 inches deep, and between 0 and 450 acres of water depths greater than 24 inches.

2. Water depths will be varied seasonally to correspond to the needs of priority resources.

3. Water level management will focus on providing 30 to 70 percent emergent vegetation cover and 30 to 70 percent open water habitat

4. Seasonally and semi-permanently flooded wetlands will be dominated (greater than 50 percent) by a dense mixture of native emergent (e.g., sedges, cattails, and bulrushes), submergent (e.g., coontail and pondweed), and floating-leaved (e.g., duckweed) wetland plants to provide forage and cover during breeding and migration seasons.

5. Undesirable invasive, exotic species will be reduced to a maximum of 10 percent total emergent vegetation cover.

6. Conduct a feasibility study to investigate alternative solutions for water level management within 3 years of the signing of this plan.

7. Reduce the amount of rough fish (fathead minnow and carp) in wetlands by drawing down infested wetlands prior to freeze up and monitor for reestablishment. Within 2 years investigate the use of electrical or physical barriers to limit reinvasion as another tool (besides water level drawdown) to limit the impact of undesired fish on the Refuge’s marsh habitats.

8. Create and implement a water monitoring plan for Refuge wetlands to track water quality and quantity data within 2 years of the signing of this plan.

Rationale

The PPR is often referred to as the “Duck Factory,” as about 50 percent of North America’s ducks are produced in this region (Mahlum and Perez 2012). A third of the North American PPR falls within the boundaries of the PPJV region (Casey et al. 2005). Previously covered by an extensive mosaic of grasslands and marshes, this landscape has been converted largely to intensive row-crop agriculture. The remaining grassland and wetland complexes that persist on the landscape are comprised primarily of restored areas and few remnant areas. According to the PPJV Implementation Plan, nearly half of all the wetlands in the PPR have been destroyed, and less than 10 percent of the pothole wetlands in the eastern portion of the region, where Union Slough NWR is located, remain (Casey et. al. 2005). According to the Iowa Wildlife Action Plan and other recent surveys in the state, only between one and five percent of Iowa’s original wetlands, including all those outside of the Prairie Pothole Region of the state remain (IDNR 2012 and 2014). Demand for agricultural crops has been and remains the driving force behind this change of landscape (Cox and Rundquist 2013). Thus the protection and restoration of remaining marshes is critical.

The plant species composition in marsh habitat on the Refuge varies among units. Some areas are dominated by cattails, which provide excellent escape cover for waterfowl and nesting structure for several species of marsh birds (Nelms et al. 2007). Although dense cattail stands can benefit waterfowl, most waterfowl species prefer wetland habitat where vegetation cover is interspersed with open water habitats. Open habitats tend to have more plant and invertebrate diversity, which provides greater forage resources for waterfowl (Kantrud 1986). Areas such as the “B” Pool in Unit 2 are dominated by sago pondweed, which provides excellent forage for waterfowl and a preferred food source for canvasback, trumpeter swan, and tundra swan (Mowbray 2002, Limpert and Earnst 1994, Mitchell and Eichholz 2010). Thus, maintaining a matrix of vegetation types, including emergent, submergent, and floating-leaved plants, will encourage a greater diversity and abundance of waterfowl to utilize the Refuge’s marshes.

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High commodity prices for corn and soybeans have increased the intensity of row-crop agriculture in the surrounding watershed. Increased tile drainage for crop production has increased the volume of water directly into the Refuge’s marsh complex. In recent years, a 10-inch tile draining into the western boundary of Union Slough NWR was replaced with a 32-inch tile line, which has more than 10 times the flow capacity of the smaller tile. The increased volume of water into the Refuge limits water management and the ability to provide wet/dry cycles that promote marsh habitat that is a mix of open water and vegetated areas. High water levels within the marsh complex can prevent certain wildlife such as mallard and blue-winged teal from easily accessing desirable plant and animal foods. In addition, prolonged periods of high water levels can greatly reduce the successful establishment of desirable aquatic vegetation, limiting cover and forage resources for marsh-dependent resources including sora, other rails, small wading birds, and waterfowl.

Union Slough forms the “union” between two watersheds: Blue Earth River to the north and the East Fork of the Des Moines River to the south. The Refuge pools are connected by water control structures and can drain to the north into the Blue Earth River or to the south into Buffalo Creek. Efforts to mimic dry cycling in Refuge pools require dewatering of downstream pools to facilitate water elevation management. Prior to the removal of Buffalo Creek Dam, drawdowns mainly occurred by forcing the water north, due to seasonally high water levels in Buffalo Creek. A feasibility study to investigate alternative solutions for water level management with the use of a pump or other means of gravity drainage may help increase the Refuges’ capacity to provide optimal habitat conditions for marsh-dependent priority resources

In addition to increased water quantity, marshes are also impacted by the chemical composition of the water entering the Refuge from tile drainage. A study conducted on the Refuge from 1995 to 1997 (Coffey 2000) found that pesticides detected in Refuge waters were below the lethal dose for fish and other aquatic organisms, but were above the level that may stress aquatic plants. Inorganic metals, such as selenium, mercury, and zinc were also found on the Refuge, along with other metals. Selenium levels decreased from the mid 1980’s to the early 1990’s, but were still at detectable levels on the Refuge, with the highest concentrations occurring in the Ruddy pool. High levels of nitrites, nitrates, and phosphorus were also found to be entering the Refuge through drainage tiles. These nutrients lead to eutrophication of the Refuge marshes, which in turn promotes algal growth and decreases light penetration creating unfavorable conditions for desirable wetland vegetation. These algal mats can also inhibit movement of wildlife, especially waterfowl and their broods, thereby lessening the desire for nesting waterfowl to use marsh habitats on the Refuge.

Rough fish such as common carp and fathead minnows (Pimephales promelas) in marshes have dramatic impacts to wetland ecology (Hanson and Butler 1994, Hanson et al. 2005). Fishless basins are more likely to have high water clarity that supports abundant vegetation and invertebrate populations, critical for breeding and migrating waterfowl and other wetland- dependent species. Rough fish stir up basin sediments leading to lower water clarity and reduced plant growth (Maurer 2013). Increased wave action due to a lack of vegetation also increases erosion along wetland shorelines and sedimentation and decreases water quality. Lowering water levels in certain units during the winter months in order to produce anoxic environments may reduce the ability of carp to survive.

Comprehensive rough fish management also should address fish re-invasion from connected waterbodies adjacent to the Refuge. Each spring, flooding allows carp and other fish species access into the Refuge. Once these fish become established, they can be difficult to remove. Fathead minnows and carp have been observed retreating into tile lines during water management draw downs and low water periods. Investigating the use of electrical or physical barriers to limit reinvasion may be another tool besides water level drawdown to limit the impact of undesired fish on the Refuge’s marsh habitats.

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The presence of invasive plant species can create difficulties in managing marsh habitats, and controlling invasive plant species is a major focus of the Refuge’s marsh management efforts. Achieving the objective requiring a maximum of 10 percent of invasive species on the Refuge’s marshes includes actively managing invasive species such as reed canary grass, which are abundant on the Refuge, as well as monitoring for species such as Eurasian watermilfoil (Myriophyllum spicatum) and purple loosestrife (Lythrum salicaria), which have not been found on the Refuge but have invaded other marsh habitats in the Midwest. Left untreated, invasive plant species often create monotypic stands, reducing plant diversity and utilization by wildlife.

Many of the edges of marshes on the Refuge are dominated by reed canary grass, which may provide some nesting cover for waterfowl such as mallard and blue-winged teal. Gathering more information is necessary to determine if this habitat is preferred by nesting waterfowl or is used because other, more preferred habitat is not available. Additional data will help direct the necessity to manage reed canary grass in this habitat.

Water levels are manipulated throughout the year to provide varying water depths and associated plant communities in order to provide habitat for various waterfowl at critical stages of their life cycle. Mudflats and shallow waters provide excellent foraging habitat for shorebirds, terns, teal, and northern shoveler. Water depths ranging from 4 to 24 inches provide ideal habitat for brood rearing, pair bonding, and providing food resources for breeding waterfowl. Emergent vegetation interspersed in areas of open water provides cover for marsh bird species including mallard, American bittern, sora, and sedge wren. Water depths greater than 24 inches provide brood rearing habitat for larger waterfowl, such as trumpeter swan and Canada goose, as well as loafing and foraging habitat.

A number of studies have concluded that waterfowl prefer an interspersion of emergent vegetation or central expanse of open water surrounded by a ring of vegetation for breeding purposes (Kantrud and Stewart 1977, Kaminski and Prince 1981, Murkin et al. 1982). In one North Dakota study, mallard hens with broods preferred seasonal wetlands with an interspersion of vegetation or central expanse of open water surrounded by a ring of vegetation (Talent et al. 1982). These wetlands are also important to shorebirds such as Virginia rail (Rallus limicola), which forage for invertebrates in the shallow water and mudflats as these basins dry up (Zimmerman et al. 2002a). Other species such as marsh wren use the dense vegetation above water or moist soil for nesting sites (Zimmerman et al. 2002b).

Neonicotinoids are a type of insecticide commonly used in agriculture to reduce insect pests in corn and soybeans. They were developed as a replacement for organophosphate insecticides and can be applied through broadcast spray application, but are more commonly being applied to both corn and soybean seed (CropLife Foundation 2013). Recently, neonicotinoids have been believed to be linked to declining populations of insect pollinators (Spivak et al. 2011). A 2013 study of nine streams in nine different agriculturally-dominated watersheds in Iowa documented the presence of neonicotinoids in surface water samples, documenting that the chemicals are persistent in the environment and can be transported from the land (Hladik et al. 2014). The concentrations of neonicotinoids in water samples appeared to increase following a precipitation event and were highest following the period after crop planting. Another study found that wetlands in agriculturally-dominated portion of the Canadian PPR accumulated neonicotinoids (Main et al. 2014). Additional information is needed to more fully understand the impacts that neonicotinoids may have to aquatic systems; however, insect production, ecological processes (litter breakdown), and wetland-dependent wildlife may be impacted in wetland habitats in agricultural landscapes including the marshes of Union Slough NWR.

Objective 3 – River Bottomland

Over the life of the HMP, manage a minimum of 536 acres of river bottomland in Unit 1 and the Buffalo Creek Unit. Maintain 157 acres of treeless habitat with a 10% increase over the next 15 years, and enhance the remaining 379 acres or less as a diverse, unevened-aged forest with a

Union Slough National Wildlife Refuge Habitat Management Plan 63 Chapter 4. Habitat Goals and Objectives mosaic of small patches (at least 5 acres in size) of grassland and sedge meadow targeted around oxbows and potholes across the Refuge to provide breeding and migratory stopover needs for Refuge priority resources, including wood duck and hooded merganser. To meet this objective:

1. Treeless areas will be composed of an herbaceous layer that comprises 10 to 95 percent cover and a shrub component that comprises 0 to 50 percent cover.

2. The forested component of river bottomland will sustain an open, native canopy tree percent cover greater than 50 percent and a shrub and herbaceous cover of 5 to 50 percent.

3. Cover of invasive species will be reduced by at least 10 percent across managed river bottomland forests.

Rationale

River bottomland is located in Unit 1 and the Buffalo Creek unit on the southern end of the Refuge, where the slough empties into Buffalo Creek. For the purposes of this HMP, river bottomland is composed of two community types: a grassland-dominated habitat, which represents historic conditions, and a forested habitat, which represents the result of a suppressed fire regime, altered hydrology, and changing land use patterns in the area of the Refuge.

Historically, this area was a treeless grassland habitat that was able to withstand varying periods of inundation. Annual forb species, which are able to take advantage of exposed soil following prolonged periods of flooding or disturbance, were likely scattered throughout. Oxbows and other small depressional pockets were created as Buffalo Creek meandered across the floodplain. Prior to settlement, wildfire combined with periodic drought maintained the absence of trees. This grass-dominated system was ideal habitat for nesting waterfowl and migratory songbirds including marsh and sedge wrens, which prefer to nest and forage in more moist conditions than upland prairie (Kroodsma and Verner 1997, Herkert et al. 2001).

The historical suppression of fire and modified hydrology due to changes in water flow across the landscape from dams, levees, and tiles created conditions that allowed for the establishment of trees and the persistence of forested communities. The river bottomland forest present on the Refuge is primarily composed of mature even-aged stands, typically made up of only one or two species. In the Buffalo Creek Unit, the dominant bottomland tree species are green ash and silver maple. Bur oak, green ash, and wild plum are the dominant species in the upland portions of the Buffalo Creek unit. Green ash is the dominant tree species in the Buffalo Creek portions in the southern part of Unit 1. Even-aged monotypic forests tend to have lower wildlife value than more diverse, uneven-aged stands. Management actions on the Refuge will focus on developing uneven-aged forest stands by creating forest openings through selective tree removal. Creating openings and selectively removing larger trees will help to develop structural heterogeneity and increase the diversity of understory vegetation, potentially providing more food and cover resources for Refuge wildlife.

Converting the entire area back to a treeless state would restore certain elements of BIDEH to the Refuge. However, the cost associated with restoration and maintenance would be high. Most management approaches would require a large commitment of Refuge labor and/or resources. Additionally, the probability for successful restoration is uncertain because critical factors such as hydrology are beyond the control of the Refuge.

In addition, access through this area of the Refuge has a significant impact on the capacity to perform effective management in river bottomlands. Buffalo Creek and the Des Moines River meander through the two units, and the floodplain is typically wet year-round, making accessing the site with large equipment difficult. Large scale tree removal would require large equipment

Union Slough National Wildlife Refuge Habitat Management Plan 64 Chapter 4. Habitat Goals and Objectives access throughout the site, and there would need to be frequent stream crossings. To maintain treeless areas after mature trees were removed, mowing or prescribed burning would be utilized. Equipment access for mowing would face the same difficulty as tree removal. Prescribed burning would offer an alternative to mowing, because natural fire breaks exist and the need for equipment could be minimized. However, the effectiveness of prescribed burning may be low at least initially due to the lack of fuel and modified hydrology resulting in extended wet conditions.

As an alternative to restoring the area to an entirely treeless habitat, the Refuge’s management of river bottomlands is focused on maintaining a minimum of 157 acres of open habitat and increasing that amount by 10 percent over the next 15 years, through small-scale tree removal projects. This work will be accomplished primarily through management techniques that can be completed without extensive use of equipment, such as chainsawing, girdling, frilling, and herbicide application. Because these are labor-intense activities, the size of an area that receives treatment will typically be limited to five acres or less. The Refuge may be able to clear trees from additional areas by including areas designated for tree removal in the firewood cutting program, which is a program that offers the public opportunities to cut trees for firewood in certain areas.

Although the forests do not necessarily represent historic conditions, they provide habitat for many wildlife species, including passerine birds, raccoons, squirrels, and predatory birds such as bald eagle and various owl species. White-tailed deer and wild turkey occur in the forested portion of the Refuge’s river bottomlands. River bottomland forests also provide habitat for wood duck and hooded merganser, which nest in cavities in mature trees. Cavity nesting sites near or over oxbows, backwater sloughs, or other wetlands are preferred by wood duck in particular for brood-rearing, although they can utilize cavities up to two kilometers away from water (Hepp and Bellrose 2013). Oxbows and other forested wetlands also provide food and cover for a variety of other wildlife, including mallard, blue-winged teal, and green heron (Butorides virescens). River bottomland forests provide cover for wildlife during severe storms or high winds. Although these and other species benefit from forested habitat, removing a portion of the trees over time will create more structural heterogeneity, which will increase its overall value to wildlife and better reflect the more open elements of the historical habitat. It will also help align the Refuge’s management with the PPJV, which does not include any goals seeking to restore forested habitats (Ringleman 2005).

The control of reed canary grass is a focus of management in both the grass-dominated and forested communities on river bottomlands. Its control is particularly difficult in the river bottomlands due to the constant seed supply from areas upstream in the watershed. As discussed under the marsh objective, reed canary grass provides some habitat for certain wildlife, and its control will need to be balanced with other management objectives.

Objective 4 – Gravel Pits

Over the life of the HMP, maintain 8 acres of habitat in the former gravel pits for the benefit of migratory waterfowl. The gravel pits will maintain open water conditions with less than 10 percent coverage by aquatic invasive species. The perimeter edge of the gravel pits will be comprised of native emergent vegetation where depth and substrate conditions allow.

Rationale

The two old gravel pits on the Refuge have filled with water and represent an artificial habitat on the Refuge that does not correspond to any historical condition. These areas may provide similar habitat to small, permanent wetlands, shallow lakes, or open water with a wetland fringe. Indeed, the gravel pits are seasonally important to migrating waterfowl. Because of the deeper water levels, they are typically the last basins to freeze up during the late fall/early winter, offering a resting place for waterfowl. Currently, the Refuge does not have any water level management control on the pits and does not anticipate having any in the future. Similar to other habitats on

Union Slough National Wildlife Refuge Habitat Management Plan 65 Chapter 4. Habitat Goals and Objectives the Refuge, woody tree species typically are not a desirable feature within the gravel pit habitat. As resources allow, trees around the gravel pits will likely be treated or removed over time, preventing them from becoming seed sources or spreading vegetatively into adjacent habitats. The same approach will be applied to other invasive species such as common reed and reed canary grass. As with marsh habitats on the Refuge, invasive carp may be problematic for the healthy functioning of these systems, particularly the development of aquatic vegetation in the littoral zone. The carp population in the gravel pits may need to be monitored in order to determine if carp management actions should be undertaken.

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Chapter 5. Management Strategies and Prescriptions

Prescribed burn in marsh habitat. Photo credit: Paul Charland/USFWS Midwest Region

5.1 Development of Management Strategies and Prescriptions 5.2 Annual Management Decision Making and Prioritization 5.3 Management Strategies by Habitat Objective

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5.1 Development of Management Strategies and Prescriptions

This chapter outlines management strategies and prescriptions to achieve the habitat management goals and objectives outlined in Chapter 4. Management strategies identify the tools and techniques (e.g. mowing, water-level manipulation, or chemical application, for example.) that would be used to achieve the habitat objectives. Prescriptions provide the details behind the specific means by which the strategies will be implemented (e.g. timing, frequency, duration, and location). The identified treatments were selected in consultation with other refuge biologists, managers, and practitioners to ensure their effectiveness. Many environmental factors, including weather, seasonal variations in temperature and precipitation, and habitat conditions, affect the ability of the selected prescriptions to achieve objectives from year to year. Therefore, many of the details regarding prescriptions will be identified further in the AHWP.

Union Slough National Wildlife Refuge (NWR) has a unique geographic position as the headwaters of two different watersheds. When a precipitation event occurs, nutrient-rich water from the surrounding landscape flows into the Refuge and is slow to move out of the system. These processes trigger algal blooms in the Refuge marsh complex. Algal blooms reduce light penetration and oxygen content in the water, which is important for aquatic macroinvertebrates and aquatic plants. These inputs make management of the Refuge resources extremely challenging. Despite the extensive planning efforts undertaken within this Habitat Management Plan (HMP), there will undoubtedly be additional need to address future changes to physical, ecological, social, political, and financial factors that influence biodiversity and its conservation.

The work outlined within this HMP is intended to be feasible given the availability of Refuge staff and an understood level of community support. As such, additions of biological technicians and other staff may help in achieving these management objectives over the next several years. The management strategies outlined here represents a comprehensive effort to guide management over the next 15 years (the lifetime of the HMP). However, it is impossible to predict the full suite of management strategies and prescriptions required over this period. Thus, some strategies may need to be amended or added as the level of available resources change over time. In that event, those amendments will be identified in the AHWP as needed.

5.2 Annual Management Decision Making and Prioritization

Each year, the Refuge intends to conduct rotating management activities on 25 percent of the Refuge (approximately 833 acres) so that over a 4-year period the entire Refuge will undergo at least some level of management. Management actions undertaken in a given year will be based on funding levels, environmental conditions, and available resources.

Management will be balanced between the maintenance and restoration of Refuge habitats, and that balance will be outlined in the Refuge’s Annual Habitat Work Plans (AHWPs). Maintenance activities are intended to maintain the current state of a habitat and prevent further degradation, and include activities such as routine herbicide, mowing, or prescribed fire treatments to prevent the encroachment of invasive or woody species. Restoration activities are intended to improve or enhance a habitat’s ecological quality or contribution to biological integrity, diversity, and environmental health (BIDEH). In practice, maintenance activities will likely account for fewer of the Refuge’s resources but account for a majority of the acres managed each year, while restoration activities will be focused on smaller areas but account for a larger percentage of the Refuge’s annual resources. The Refuge believes that actively performing some level of management on approximately 833 acres per year (or 25 percent of Union Slough’s 3,334 acres) will maintain and restore BIDEH on the Refuge while efficiently utilizing limited resources.

At the broadest scale, the following management strategies are described according to each habitat type on the Refuge, and are aligned with the four habitat objectives introduced in Chapter 4. However, specific units or subunits within the Refuge are identified in the strategies to provide

Union Slough National Wildlife Refuge Habitat Management Plan 68 Chapter 5. Management Strategies and Prescriptions

a greater level of detail where appropriate. Although Chapter 2 discussed the existing conditions of each unit, Table 5-1 provides a summary of the habitat types contained in each unit, as well as each unit’s associated habitat objectives.

Table 5-1. Distribution of Refuge Habitats Across Management Units at Union Slough NWR.

Management Unit Habitat Habitat Objective Acres Schwob Marsh Unit Marsh 2 140 Schwob Marsh Unit Prairie/Grassland 1 125 Unit 5 Marsh 2 144 Unit 5 Prairie/Grassland 1 100 Unit 4 Marsh 2 167 Unit 4 Prairie/Grassland 1 131 Unit 3 Marsh 2 277 Unit 3 Prairie/Grassland 1 250 Unit 3 Gravel Pits 4 8 Unit 2 Marsh 2 366 Unit 2 Prairie/Grassland 1 501 Unit 1 Marsh 2 106 Unit 1 Prairie/Grassland 1 324 Unit 1 River Bottomlands 3 146 Buffalo Creek Unit Prairie/Grassland 1 159 Buffalo Creek Unit River Bottomlands 3 390 Total: 3,334

5.3 Management Strategies by Habitat Objective

Objective 1 – Prairie/Grassland

Over the life of the HMP, sustain and enhance a minimum of 1,590 acres of prairie and other grassland habitats across the Refuge to provide breeding, foraging, rearing, and migratory stopover needs for Refuge priority resources such as grassland-dependent wildlife including mallard, blue-winged teal, upland sandpiper, grasshopper sparrow, bobolink, and regal fritillary, while also providing for the full life cycle requirements of prairie bush clover. To meet this objective:

1. All grasslands will sustain a total vegetated cover of greater than 90 percent perennial herbaceous species, in which the forb component is between 5 and 50 percent.

2. Vegetation will be enhanced to promote a dominance of native species such as big bluestem, little bluestem, Indian grass, Canada wild rye, porcupine grass, as well as a diverse forb community that includes asters, coneflower, lead plant, and other native prairie species.

3. Cover of invasive, exotic species will be less than 10 percent across managed prairies and grasslands.

4. Invasive woody vegetation will be less than 10 percent across managed prairies and grasslands.

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Management Strategies

Continue to:

• Burn approximately 400 acres per year of prairies and grasslands (minor component of marsh) to reduce encroachment of woody stems and promote native grasses and forbs.

• Treat invasive species by mowing, disking, spot spraying, and boom spraying as appropriate to sustain and enhance the integrity of the prairies and other grasslands.

• Remove trees as needed by girdling/frilling, cut-stump treatment, basal bark spraying, and/or mowing.

• Allow the public to obtain a special use permit to cut firewood from August 1 to April 1 where tree removal is needed.

Future management actions, in order of priority:

• Within three years of the HMP, treat invasive species, with intensive focus on crown vetch, through alternative strategies of integrated pest management at known locations of prairie bush clover.

• Within three years of the HMP, delineate grasslands dominated by Kentucky bluegrass and/or smooth brome where haying could be used to add structural diversity in the short- term. When combined with chemical application, these hayed areas will provide great opportunity for long-term conversion to diverse native prairie.

• Within five years of the HMP, assess and map all grasslands to determine the extent and status of high quality remnants, degraded remnants, reconstructed prairies, and smooth brome/Kentucky bluegrass grasslands in order to prioritize management actions.

• Over the life of the HMP, seed up to 20 acres per year using seed mixes comprised of 50 to 100 species of native prairie grasses and forbs. Ideally, a 50:50 grass to forb ratio would be used, but actual mix is determined by budget and seed availability constraints.

• As resources become available, utilize grazing, disking, burning, and chemical application to prepare smooth brome/Kentucky bluegrass grasslands for prairie reconstruction.

• Use annual browse crops such as oats, wheat, rye, millet, etc. to assist in preparation for seeding diverse native plant species.

Objective 2 – Marsh

Over the life of the HMP, annually sustain or enhance a minimum of 1,200 acres of marsh habitat across all Refuge units and provide breeding and migratory stopover for Refuge priority resources such as waterfowl including mallard, blue-winged teal, trumpeter swan, wood duck, and lesser scaup, as well as other migratory birds such as lesser yellowlegs, sora, sedge wren, and American bittern. Marsh habitat will have the following conditions:

1. Between March and November each year, provide between 0 and 240 acres of water depths ranging from 0 (mudflat) to 4 inches deep, between 120 and 720 acres of water depths ranging from 4 to 24 inches deep, and between 0 and 450 acres of water depths greater than 24 inches.

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2. Water depths will be varied seasonally to correspond to the needs of priority resources.

3. Water level management will focus on providing 30 to 70 percent emergent vegetation cover and 30 to 70 percent open water habitat

4. Seasonally and semi-permanently flooded wetlands will be dominated (greater than 50 percent) by a dense mixture of native emergent (e.g., sedges, cattails, and bulrushes), submergent (e.g., coontail and pondweed), and floating-leaved (e.g., duckweed) wetland plants to provide forage and cover during breeding and migration seasons.

5. Undesirable invasive, exotic species will be reduced to a maximum of 10 percent total emergent vegetation cover.

6. Conduct a feasibility study to investigate alternative solutions for water level management within 3 years of the signing of this plan.

7. Reduce the amount of rough fish (fathead and carp) in wetlands by drawing down infested wetlands prior to freeze up and monitor for reestablishment. Within 2 years investigate the use of electrical or physical barriers to limit reinvasion as another tool (besides water level drawdown) to limit the impact of undesired fish on the Refuge’s marsh habitats.

8. Create and implement a water monitoring strategy for Refuge wetlands to track water quantity data within 2 years of signing this HMP.

9. Conduct water quality monitoring for nitrogen and phosphorus at known tile inlets into the Refuge and Refuge outlets within three years of the signing of the HMP. Dovetail efforts with previous contaminant study. As resources allow, expand efforts to include monitoring for pesticides.

Management Strategies

Continue to:

• Manipulate water levels in each management unit as appropriate to achieve depths described in the objective.

• Maintain all water control structures, levees, and water gauges.

• Control woody vegetation outside of the nesting season through mowing, chemical application, cut-stump, girdling, and frilling.

• Burn to reduce cattail and thatch in order to allow wildlife to move more freely through marsh areas and promote a greater diversity of native plant species. o Evaluate the feasibility of conducting burns outside of the spring season.

• Utilize physical disturbance such as a Marshmaster or chemical treatments to create openings in dense areas of cattail.

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Future management actions, in order of priority:

• Within one year of the HMP, update and implement annual water management plan.

• Over the life of the HMP, draw down each unit completely for a minimum of 14 days, through either natural conditions or management actions, up to five times if necessary, based on presence of rough fish, vegetation abundance, food resources, and water quality values. o Time the drawdowns based on current year conditions and management objectives as outlined by the annual water management plan.

• Document water quality/quantity problems on Union Slough NWR related to the watershed it lies within. This will provide information on current conditions and compare changes relative to conditions measured in the mid 1990’s. It may also identify future threats and information needs. The information gathered will provide data needed to educate Refuge neighbors and the general public on the consequences of current practices in the watershed. Ideally, this will lead to changes such as grassed waterways, bioreactors in tile lines to reduce nitrates, or the installation of treatment wetlands to improve the water quality before it enters the Refuge.

• Within three years of the HMP, conduct a feasibility study to evaluate methods for carp/fish exclusion on the Refuge.

• Within five years of the HMP, evaluate methods to reduce reed canary grass through a combination of mechanical efforts, chemical treatment with seeding, and sediment removal. If successful, apply that approach to larger areas within the Refuge.

• As resources become available and as drought or dry conditions allow, prepare for and implement sediment removal projects. Focus on areas with monotypic cattail stands to increase open water areas and plant diversity.

• On an annual basis, evaluate alternative methods to control or provide longer-term setback of cattail.

• Within five years of the HMP, investigate options to improve Schwob Marsh Unit’s dike system. Investigate slowing down water from ditch, including check dams, and rerouting to the first cell.

• Within five years of the HMP, develop a decision support tool for invasive species management.

• Within the lifetime of this HMP, conduct a feasibility study for installing pumps for managing water levels on the Refuge.

Objective 3 – River Bottomlands

Over the life of the HMP, manage a minimum of 536 acres of river bottomland in Unit 1 and the Buffalo Creek Unit. Maintain 157 acres of treeless habitat with a 10% increase over the next 15 years, and enhance the remaining 379 acres or less as a diverse, uneven-aged forest with a mosaic of small patches (at least 5 acres in size) of grassland and sedge meadow targeted around oxbows and potholes across the Refuge to provide breeding and migratory stopover needs for Refuge priority resources, including wood duck and hooded merganser. To meet this objective:

Union Slough National Wildlife Refuge Habitat Management Plan 72 Chapter 5. Management Strategies and Prescriptions

1. Treeless areas will be composed of an herbaceous layer that comprises 10 to 95 percent cover and a shrub component that comprises 0 to 50 percent cover.

2. The forested component of river bottomland will sustain an open, native canopy tree percent cover greater than 50 percent and a shrub and herbaceous cover of 5 to 50 percent.

3. Cover of invasive species will be reduced by at least 10 percent across managed river bottomland forests.

Management Strategies

Continue to:

• Allow the public to obtain a special use permit to cut firewood from August 1 to April 1 on Unit 1, Buffalo Creek Unit, and other units where tree removal is needed.

Future management actions, in order of priority:

• Create one opening per year, with a minimum patch size of 5 acres, using various methods such as girdling, basal bark spraying, cut stump treatment, and frilling while leaving 1 dead tree/acre or more for cavity nesting ROCs.

• Monitor the response of native vegetation establishment and persistence within created openings to guide management actions on the capabilities of controlling invasive species in other areas of the units.

• Annually evaluate the response of reed canary grass suppression in patch creation areas.

• Within 3 years of the HMP, locate equipment access sites to subunit 25, located in the Buffalo Creek Unit, with the intention of maintaining bottom land habitats of rice cutgrass and smartweed.

Objective 4 – Gravel Pits

Over the life of the HMP, maintain 8 acres of habitat in the former gravel pits for the benefit of migratory waterfowl. The gravel pits will maintain open water conditions with less than 10 percent coverage by aquatic invasive species. The perimeter edge of the gravel pits will be comprised of native emergent vegetation where depth and substrate conditions allow.

Management Strategies

Continue to:

• Control woody vegetation around gravel pits outside of the nesting season through mowing, chemical application, cut-stump, girdling, and/or frilling.

Future management actions, in order of priority:

• Annually monitor and control invasive species by herbicide applications, mowing, haying, grazing and/or prescribed burning.

Union Slough National Wildlife Refuge Habitat Management Plan 73 Chapter 5. Management Strategies and Prescriptions

• Monitor carp populations in gravel pits and identify if control is needed to encourage the development of desirable aquatic vegetation in the littoral zones.

Union Slough National Wildlife Refuge Habitat Management Plan 74 References

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Union Slough National Wildlife Refuge Habitat Management Plan 82 Appendix A

Appendix A

Potential Resources of Concern

Union Slough National Wildlife Refuge Habitat Management Plan Appendix A

Birds

Waterbirds Common Name Scientific Name American bittern Botaurus lentiginosus American white pelican Pelecanus erythrorhynchos Black rail Laterallus jamaicensis Black tern Chlidonias niger Black-crowned night-heron Nycticorax nycticorax Common moorhen Gallinula chloropus Forster’s tern Sterna forsteri Horned grebe Podiceps auritus King rail Rallus elegans Least bittern Ixobrychus exilis Least tern Sterna antillarum Pied-billed grebe Podilymbus podiceps Sandhill crane Grus canadensis Sora Porzana carolina Virginia rail Rallus limicola Whooping crane Grus americana Yellow-crowned night-heron Nyctanassa violacea Yellow rail Coturnicops noveboracensis

Shorebirds Common Name Scientific Name American Avocet Recurvirostra americana American Golden Plover Pluvialis dominica American Woodcock Scolopax minor Buff-breasted Sandpiper Tryngites subruficollis Dunlin Calidris alpina Greater Yellowlegs Tringa melanoleuca Hudsonian Godwit Limosa haemastica Lesser Yellowlegs Tringa flavipes Marbled Godwit Limosa fedoa Piping Plover Charadrius melodus Semipalmated Sandpiper Calidris pusilla Short-billed Dowitcher Limnodromus griseus Solitary Sandpiper Tringa solitaria Stilt Sandpiper Calidris himantopus Upland Sandpiper Bartramia longicauda Whimbrel Numenius phaeopus Wilson's Phalarope Phalaropus tricolor

Union Slough National Wildlife Refuge Habitat Management Plan Appendix A

Waterfowl Common Name Scientific Name American Wigeon Anas americana Blue-winged Teal Anas discors Bufflehead Bucephala albeola Canada Goose Branta canadensis Canvasback Aythya valisineria Common Goldeneye Bucephala clangula Common Merganser Mergus merganser Gadwall Anas strepera Greater White-fronted Goose Anser albifrons Green-winged Teal Anas crecca Hooded Merganser Lophodytes cucullatus Lesser Scaup Aythya affinis Mallard Anas platyrhynchos Northern Pintail Anas acuta Northern Shoveler Anas clypeata Red-breasted Merganser Mergus serrator Redhead Aythya americana Ring-necked Duck Aythya collaris Ross's Goose Chen rossii Ruddy Duck Oxyura jamaicensis Snow Goose Chen caerulescens Trumpeter Swan Cygnus buccinator Tundra Swan Cygnus columbianus Wood Duck Aix sponsa

Landbirds Common Name Scientific Name Acadian Flycatcher Empidonax virescens Bald Eagle Haliaeetus leucocephalus Bell's Vireo Vireo bellii Black-and-white Warbler Mniotilta varia Black-billed Cuckoo Coccyzus erythropthalmus Blue-winged Warbler Vermivora cyanoptera Bobolink Dolichonyx oryzivorus Broad-winged Hawk Buteo platypterus Brown Creeper Certhia americana Brown Thrasher Toxostoma rufum Burrowing Owl Athene cunicularia Canada Warbler Cardellina canadensis Cerulean Warbler Setophaga cerulea Clay-colored Sparrow Spizella pallida

Union Slough National Wildlife Refuge Habitat Management Plan Appendix A

Common Nighthawk Chordeiles minor Dickcissel Spiza americana Eastern Meadowlark Sturnella magna Eastern Towhee Pipilo erythrophthalmus Field Sparrow Spizella pusilla Golden-winged warbler Vermivora chrysoptera Grasshopper Sparrow Ammodramus savannarum Henslow’s Sparrow Ammodramus henslowii Hooded Warbler Setophaga citrina Kentucky Warbler Geothlypis formosus Le Conte's Sparrow Ammodramus leconteii Least Flycatcher Empidonax minimus Loggerhead Shrike Lanius ludovicianus Long-eared Owl Asio otus Louisiana Waterthrush Parkesia motacilla Marsh Wren Cistothorus palustris Nelson’s Sharp-tailed Sparrow Ammodramus nelsoni Northern Flicker Colaptes auratus Northern Harrier Circus cyaneus Orchard Oriole Icterus spurius Osprey Pandion haliaetus Peregrine Falcon Falco peregrinus Prothonotary Warbler Protonotaria citrea Red-headed Woodpecker Melanerpes erythrocephalus Red-shouldered hawk Buteo lineatus Rusty Blackbird Euphagus carolinus Sedge Wren Cistothorus platensis Short-eared Owl Asio flammeus Smith’s Longspur Calcarius pictus Swainson's Hawk Buteo swainsoni Veery Catharus fuscescens Vesper Sparrow Pooecetes gramineus Willow Flycatcher Empidonax traillii Wood thrush Hylocichla mustelina Yellow-billed Cuckoo Coccyzus americanus

Union Slough National Wildlife Refuge Habitat Management Plan Appendix A

Mammals

Common Name Scientific Name Bobcat Lynx rufus Flying Squirrel Glaucomys volans Franklin's ground squirrel Spermophilus franklinii Gray fox Urocyon cinereoargenteus Hayden's shrew Sorex haydeni Northern myotis Myotis septentrionalis Plains pocket gopher Geomys bursarius Prairie vole Microtus ochrogaster Red squirrel Tamiasciurus hudsonicus River otter Lutra canadensis Southern bog lemming Synaptomys cooperi Spotted skunk Spilogale putorius Whitetail jackrabbit Lepus townsendi

Reptiles and Amphibians

Common Name Scientific Name Blanding’s Turtle Emydoidea blandingii Northern Cricket Frog Acris crepitans Northern Prairie Skink Eumeces septentrionalis Smooth Greensnake Opheodrys vernalis Tiger salamander Ambystoma tigrinum

Fish

Common Name Scientific Name Blackside Darter Percina maculata Common carp Cyprinus carpio Redfin shiner Lythrurus umbratilis Slenderhead darter Percina phoxocephala Tadpole madtom Noturus gyrinus Topeka shiner Notropis topeka

Union Slough National Wildlife Refuge Habitat Management Plan Appendix A

Mussels and Snails

Common Name Scientific Name Asian clam Corbicula fluminea Creek heelsplitter Lasmigona compressa Cylinder Anodontoides ferussacianus Elktoe Alasmidonta marginata Ellipse Venustaconcha ellipsiformis Fluted shell Lasmigona costata Lilliput Toxolasma parvus Monkeyface Quadrula metanevra Paper pondshell Utterbackia imbecillis Round pigtoe Pleurobema coccineum Slough sandshell Lampsilis teres Spike Elliptio dilatata Strange floater (Squawfoot) Strophitus undulatus Yellow sandshell Lampsilis teres Zebra mussel Dreissena polymorpha

Insects - Lepidoptera

Common Name Scientific Name Aphrodite fritillary Speyeria aphrodite Arogos Skipper Atrytone arogos Broad-winged Skipper Poanes viator Dion (Sedge) Skipper Euphyes dion Mulberry Wing Poanes massasoit Poweshiek skipperling Oarisma powesheik Reakirt’s Blue Echinargus isola Regal fritillary Speyeria idalia

Insects - Odonata

Common Name Scientific Name Alkali Bluet Enallagma clausum Blue-eyed darner Aeshna multicolor Prairie Bluet Coenagrion angulatum Variable Darner Aeshna interrupta

Union Slough National Wildlife Refuge Habitat Management Plan Appendix A

Plants

Common Name Scientific Name Beaked rush Rhynchospora capillacea Blue giant-hyssop Agastache foeniculum Blue wild indigo Baptisia australis Bog bedstraw Galium labradoricum Bog buckbean Menyanthes trifoliata Bog willow Salix pedicellaris Brook lobelia Lobelia kalmii Coast blite Chenopodium rubrum Common mare’s-tail Hippuris vulgaris Cordroot sedge Carex chordorrhiza Double sedge Carex diandra False golden ragwort Senecio pseudaureus Few-flowered spikerush Eleocharis pauciflora Fragrant false indigo Amorpha nana Golden corydalis Corydalis aurea Hill’s thistle Cirsium hillii Kittentails Besseya bullii Large arrowgrass Triglochin maritimum Large-leaved pondweed Potamogeton amplifolius Low nutrush Scleria verticillata Northern bog orchid Platanthera hyperborea Pale green orchid Platanthera flava Philadelphia panic-grass Panicum philadelphicum Pink turtlehead Chelone obliqua Prairie bush clover Lespedeza leptostachya Purple angelica Angelica atropurpurea Ribbonleaf pondweed Potamogeton epihydrus Richardson’s sedge Carex richardsonii Rush aster Aster junciformis Saskatoon serviceberry Amelanchier alnifolia Shining willow Salix lucida Showy evening primrose Oenothera speciosa Showy milkweed Asclepias speciosa Silverweed Potentilla anserina Slender cottongrass Eriophorum gracile Slender ladies-tresses Spiranthes lacera Small arrowgrass Triglochin palustre Small bladderwort Utricularia minor Small fringed gentian Gentianopsis procera Small white lady’s-slipper Cypripedium candidum

Union Slough National Wildlife Refuge Habitat Management Plan Appendix A

Soft sedge Carex tenera Spiralled pondweed Potamogeton spirillus Swamp thistle Cirsium muticum Tall cottongrass Eriophorum angustifolium Toad rush Juncus bufonius Tooth-cup Rotala ramosior Tussock pondweed Potamogeton strictifolius Water milfoil Myriophyllum heterophyllum Water milfoil Myriophyllum verticillatum Water parsnip Berula erecta Watershield Brasenia schreberi Water-starwort Callitriche heterophylla Wavy-leaved thistle Cirsium undulatum Western parsley Lomatium orientale Western prairie fringed orchid Platanthera praeclara Wolf’s spikerush Eleocharis wolfii Woolly milkweed Asclepias lanuginosa Yellow monkeyflower Mimulus glabratus

Union Slough National Wildlife Refuge Habitat Management Plan Appendix B

Appendix B

ROCSTAR Scoring Evaluation

Union Slough National Wildlife Refuge Habitat Management Plan Appendix C

Appendix C

HMP Development Team

Union Slough National Wildlife Refuge Habitat Management Plan Appendix C

Service Authors Ed Meendering Project Leader Union Slough National Wildlife Refuge

Tim Miller Project Leader Union Slough National Wildlife Refuge

Tom Skilling Refuge Biologist Union Slough National Wildlife Refuge

Kathleen Carlyle U.S. Fish and Wildlife Service

Erich Gilbert Assistant Project Leader Union Slough National Wildlife Refuge

Contractual Authors Mark Pranckus Senior Project Scientist Cardno JFNew

Michael Steiner Senior Staff Scientist Cardno JFNew

Justin Heslinga Senior Staff Scientist Cardno JFNew

Union Slough National Wildlife Refuge Habitat Management Plan Appendix D

Appendix D

Grazing/Haying Program Management Plan

Union Slough National Wildlife Refuge Habitat Management Plan

Union Slough National Wildlife Refuge Habitat Management Plan