Managing for Monarchs in the West: Bmps for Conserving the Monarch
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Managing for Monarchs in the West Best Management Practices for Conserving the Monarch Butterfly and its Habitat MANAGING FOR MONARCHS IN THE WEST Best Management Practices for Conserving the Monarch Butterfly and its Habitat Emma Pelton Stephanie McKnight Candace Fallon Aimée Code Jennifer Hopwood Sarah Hoyle Sarina Jepsen Scott Hoffman Black The Xerces Society for Invertebrate Conservation www.xerces.org The Xerces® Society for Invertebrate Conservation is a nonprofit organization that protects wildlife through the conservation of invertebrates and their habitat. Established in 1971, the Society is at the forefront of invertebrate protection, harnessing the knowledge of scientists and the enthusiasm of citizens to implement conservation programs worldwide. The Society uses advocacy, education, and applied research to promote invertebrate conservation. The Xerces Society for Invertebrate Conservation 628 NE Broadway, Suite 200, Portland, OR 97232 Tel (855) 232-6639 Fax (503) 233-6794 www.xerces.org Regional offices from coast to coast. The Xerces Society is an equal opportunity employer and provider. Xerces® is a trademark registered in the U.S. Patent and Trademark Office © 2018 by The Xerces Society for Invertebrate Conservation Primary Authors and Contributors The Xerces Society for Invertebrate Conservation: Emma Pelton, Stephanie McKnight, Candace Fallon, Aimée Code, Jennifer Hopwood, Sarah Hoyle, Sarina Jepsen, and Scott Hoffman Black Acknowledgments Funding for this project was provided by the National Fish and Wildlife Foundation, US Forest Service, Bureau of Land Management, and US Fish and Wildlife Service with additional support from Ceres Trust, CS Fund, The Dudley Foundation, The Edward Gorey Charitable Trust, Endangered Species Chocolate, LLC, J. Crew, Justin’s, Madhava Natural Sweeteners, The New-Land Foundation, Inc., San Diego Zoo, Turner Foundation, Inc., White Pine Fund, Whole Systems Foundation, and Xerces Society members. The authors wish to thank everyone who contributed to the development of this guidance: the twelve interviewees, forty-three survey respondents, and additional researchers and practitioners with whom we had informal conversations. Xerces Society staff members Jessa Kay Cruz, Rich Hatfield, Eric Lee-Mäder, Ray Moranz, Kat Prince, and Mace Vaughan contributed to the development and review of specific sections. Content for the case studies was developed with contributions from Lora Haller of US Fish and Wildlife Service (Case Study 3), Rose Lehman of US Forest Service (Case Study 5), and Beth Waterbury of Idaho Department of Fish and Game (Case Study 7). Cheryl Schultz of Washington State University–Vancouver provided review of specific sections. Editing: Matthew Shepherd, The Xerces Society Layout: Michele Blackburn, The Xerces Society Printing: Print Results, Portland, OR In accordance with Federal law and US Department of Agriculture policy, this institution is prohibited from discriminating on the basis of race, color, national origin, sex, age, or disability. (Not all prohibited bases apply to all programs.) To file a complaint of discrimination, write USDA, Director, Office of Civil Rights, Room 326-W, Whitten Building, 1400 Independence Avenue, SW, Washington, DC 20250-9410 or call (202) 720-5964 (voice and TDD). USDA is an equal opportunity provider and employer. Recommended Citation The Xerces Society. 2018. Managing for Monarchs in the West: Best Management Practices for Conserving the Monarch Butterfly and its Habitat. 106+vi pp. Portland, OR: The Xerces Society for Invertebrate Conservation. (Available online at www.xerces.org). Photographs & Artwork We are grateful to the many photographers and designers for allowing us to use their wonderful photographs and artwork. The copyright for all photographs, icons, and designs is retained by the Xerces Society or the creators. None of the photographs or artwork may be reproduced without permission. For a complete list of photographers and designers, please see the Photo Credits section on page 106. If you wish to contact a photographer or designer, please contact the Xerces Society at the address above. Cover Photograph A monarch on swamp milkweed near wetlands by Stephanie McKnight.. Contents Executive Summary v Introduction 1 Meet the Butterfly 4 Monarch Life Cycle 4 Migration and Distribution 4 Conservation Status 7 Threats to Monarchs 7 Habitat Loss 7 Insecticides 8 Climate Change 9 Parasites, Diseases, and Predators 11 What is High-Quality Monarch Habitat? 13 Milkweed Species 14 Milkweed Diversity and Distribution 14 Milkweed Phenology 15 Milkweed Identification 17 Nectar Species 17 Approach to Monarch Habitat Conservation 19 Priority Areas for Habitat Conservation and Restoration 19 Issues with Planting Milkweed Outside its Historic Range 21 Best Management Practices for Monarch Habitat 23 Management Timing 23 Grazing 25 Grazing Best Management Practices 29 Mowing 34 Mowing Best Management Practices 36 Roadsides and Other Rights-of-Way 37 Prescribed Fire 39 Prescribed Fire Best Management Practices 41 Pesticides 42 Pesticide Best Management Practices 43 Grasshopper and Mormon Cricket Management 45 Restoration 46 Restoration Best Management Practices 48 Milkweed Species Selection 49 Recommendation Against Planting Nonnative Milkweeds 50 Milkweed Establishment Guidance 51 Milkweed Patch Density, Size, and Connectivity 52 Nectar Plant Species Selection 54 Sourcing Native Plant Materials 55 Water and Irrigation 57 Agricultural Areas 58 Post-Wildfire Restoration 59 Gardens and Urban or Suburban Areas 59 Invasive Nonnative and Noxious Plant Management 60 Invasive Plant Best Management Practices 62 Other Considerations 64 Climate Change 64 Recreation 65 Monitoring Monarch Populations 66 Tagging and Tracking Programs 70 Resources 72 General Monarch Resources 72 Western Monarch Breeding and Migratory Habitat 72 California Overwintering Sites 72 Literature Cited 73 Appendix 1. Western Milkweed Species by State 86 Appendix 2. Native Monarch Nectar Plants in the West 104 Executive Summary Western monarchs are in trouble. The number of monarchs overwintering in coastal California has declined by over 95% since the 1980s, with declines also observed in breeding populations during the spring and summer. An increasing number of people are wondering what they can do to save the butterfly and its milkweed host plant. To help them, the Xerces Society for Invertebrate Conservation has developed guidance on how to manage existing monarch breeding and migratory habitat and where and when to restore the butterfly’s habitat in the western United States; overwintering habitat is covered in the Xerces Society’s publication Protecting California’s Butterfly Groves: Management Guidelines for Monarch Butterfly Overwintering Habitat. These guidelines were informed by a literature review, surveys and interviews with monarch butterfly experts and public land managers, and by field experience. Threats to monarchs are summarized and include habitat loss, insecticides, climate change, and parasites, diseases, and predators. Consistent with the wide-ranging nature of the monarch butterfly, suitable breeding and migratory habitat is widespread across the West. Habitat suitability modeling shows there are notable concentrations of potentially highly suitable habitat in the Central Valley of California as well as in southern Idaho and eastern Washington; smaller areas are evident across northern Nevada, southern Arizona, parts of Utah, most low-elevation lands in Oregon excluding the coast, and other areas. Widespread planting of milkweed is often the response to help monarchs. However, this is not a recommended strategy across the western US. Instead, the Xerces Society recommends a more holistic and targeted approach to monarch conservation. The three components of this are, in order of importance: 1. Identify, protect, and manage existing habitat to maintain its value for monarchs. 2. Enhance existing habitat (if needed and appropriate) to improve its value for monarchs. 3. Restore habitat in areas where it occurred historically, but has been lost. High-quality monarch breeding and migratory habitat offers native milkweeds to provide food for caterpillars (and nectar for adults) and other flowers—preferably native—to provide nectar for adults. Habitat should be safe from pesticides and keep butterflies free from high levels of pathogens. Additional factors such as roosting habitat and shade may also be important features of high-quality habitat. These best management practices (BMPs) provide a brief summary of the known effects of frequently used land management practices on monarchs and their breeding/migratory habitat, followed by recommendations on how to incorporate monarch conservation into management decisions. The BMPs include ecoregion-specific recommendations for management timing and cover the practices of grazing, mowing, prescribed fire, and pesticides. An overview of monarch habitat restoration—including native milkweed A monarch nectars on narrowleaf milkweed. and nectar plant species lists as well as native plant sourcing and establishment—provides managers with the necessary technical guidance to incorporate monarchs’ needs into projects. Invasive nonnative and noxious plant management, recreation, and climate change impacts are also addressed. Sections on monitoring monarch populations (including major tagging and tracking programs) and resources to learn about western monarch conservation wrap up the document. To help reverse the western