Migration and conservation: frameworks, gaps, and synergies in science, law, and management.

• Author: Meretsky, Vicky J.

1. Introduction II. Existing Ecological Typologies of Migration A. What Is Migration? B. Why Migrate? C. The Geography of Migration D. Who Migrates? E. The Timing of Migration F. Genetics, Learning, and Navigation G. Future Directions in Migration Research III. Typology of Existing Legal Approaches A. Funding, Assistance, Coordination, and information Generation and Exchange B. State Conservation Planning in Exchange for Federal Incentives C. Acquiring and Designating Habitat for the Benefit of Species Individuals and Populations D. Controls on "Take" of Species' Individuals, Including Prohibitions and Harvest Restrictions E. Standards and Management Practices to A void Harm to Individuals and Populations F. Concluding Thoughts IV. Typologies Related to Wildlife Management A. Management. Contexts 1. Wildlife Management in the Context of Land Management a. Federal Lands b. Non-Federal Lands 2. Wildlife Management in the Context of Federal and State Waters a. Waters of the United States b. State Waters 3. Wildlife Management in the Context of Species Management B. Management Tools for Conserving Migratory Species 1. Tools for Land Management 2. Tools for Species Management 3. Interjurisdictional, Landscape-Scale Management C. Migration Typology for Managers V. Discussion A. Synergies in Migration Research, Policy, and Management B. Gaps in Migration Conservation 1. Gaps in Scientific Information to Support Conservation of Migratory Species 2. Gaps in Laws and Policies a. Gaps in Addressing Fragmentation and Obstacles b. Jurisdictional Gaps c. Taxonomic Gaps d. Gaps in Spatial Coverage e. Limitations on Protection at Ecologically Relevant Levels f. Summary of La wand Policy Gaps 3. Gaps in Management Focus and Needs C. Improving Conservation of Migrants and Migrations VI. Conclusion I. INTRODUCTION

   Migratory species once created some of the biggest natural spectacles on the planet: flocks of migrating birds that darkened the skies, (1) migrations of antelope and bison that covered African and North American grasslands from horizon to horizon, (2) sea turtles in the Caribbean so dense that "it seemed that the ships would run aground on them." (3) Abundance made many of these species attractive targets for hunters and fishers. Some, such as the passenger pigeon (Ectopistes migratorius), have been lost; (4) others were rescued from extinction when public outcry led to changes in laws protecting them. (5) In the United States, the Lacey Act (6) and the Migratory Bird Treaty Act (MBTA) (7) helped bring to a close the unregulated market hunting of waterfowl and shorebirds and the more focused--but no more sustainable--hunting of migratory waterbirds and songbirds for the millinery trade in ladies' hats. (8)

   If the abundance of many migratory species once made them obvious targets for hunting, the movements of migratory species now place them at risk due to loss of habitat, barriers to movement, and mortality from obstacles, pollution, as well as legal and illegal hunting. However, in the absence of evidence of overwhelming mortality such as preceded the MBTA, little additional protection has been extended to these species that run their respective migratory gauntlets year in and year out. At one time, immensely effective protection was afforded one large taxon (9) (birds) simply by modifying one activity (hunting). To seek, now, to protect the wide variety of migratory taxa at levels that allow them to be ecologically relevant and to continue to provide phenomena of abundance requires modifying many aspects of human undertakings.

   There is room for optimism, however. Public interest in migration and migratory species is strong. Students learn geography studying the travels of migratory monarch butterflies (Danaus plexippus), and interact with their peers in other nations. (10) Touring companies and town festivals profit from our ongoing fascination with the phenomenon of migration. (11) Yet numbers of many migratory species continue to decline. (12)

   Changing the conservation landscape to improve protection of migratory species is a complex undertaking. Effective conservation of migrants requires coordinated work by researchers, lawyers and policy makers, and natural resource managers. In this Article, we begin by describing the frameworks used in these three disciplines to categorize migrations and migratory species. These discussions are intended to be descriptive, rather than critical, as no one discipline of the three can be, or claims to be, a complete solution to the problem of conservation of migratory species. Throughout, we seek to communicate the information of all three fields in terms accessible to researchers studying any aspect of migration--legal scholars, who study patterns and trends in legal practice; legal practitioners, who work on behalf of clients to interpret and make use of aspects of the legal system; land managers, who manage wildlife on their properties; and wildlife managers, who are responsible for conservation and management of wildlife species without regard to property boundaries.

   We then use these frameworks to identify areas of synergy where disciplines approach the subject of migration in complementary ways and support conservation. In particular, several of the distinctions that arise out of research, such as whether migrants concentrate along a narrow migratory route or disperse across a broad front, are important distinctions for policy and management. Not surprisingly, however, the frameworks of the three disciplines are not entirely overlapping, and we identify gaps where differences in approaches weaken conservation of these species. For example, research does not provide strong population estimates for many migratory species, but even where such information is available, it is rarely incorporated into policy in a way that protects migratory species at population levels that ensure ecological relevance.

   Finally, we suggest ways of advancing work in all three disciplines individually and collaboratively to improve conservation of migrations and migratory species. We recommend increased communication and collaboration among the disciplines, generally, but also recommend a focused exercise, such as a regularly scheduled conference or workshop, to identify pressing questions of policy makers and managers that could become funding targets for public and private funding sources. We suggest that state-level programs provide either a foundation to augment, or a model on which to build, conservation efforts targeting migratory species. Federal coordination could help to organize regional and national landscape protections; commitment to management standards and practices would ensure consistency. We view most problems associated with conservation of migration as entirely soluble and see evidence of support for conservation of migratory species in society at large.

   Part II, the first of our disciplinary parts, delineates the breadth of natural diversity that comes under the umbrella of migration, describing the kinds of migratory species and varieties of migratory behaviors defined by scientific research. Research on migration is often oriented around taxonomic, ecological, and evolutionary areas of interest. Taxonomic focus may be at levels as narrow as individual populations or as broad as all vertebrates. Ecological studies related to migration examine relationships between organisms and their physical and biological environments during part or all of a migration cycle. Evolutionary inquiries track the evolution of mechanisms that underlie physical, ecological, and social aspects of migration.

   Part II.A explores the boundaries of what is meant by migration. Part II.B explains those ecological and environmental factors that motivate species to migrate. The ways in which migration can proceed across the land, through the air, or through the water are described in Part U.C. The question of which characteristics of individuals--gender, physical condition, age-are associated with migration is dealt with in Part II.D. Part ILE explains how the seasonal timing of migration is determined and affected. Part II.F discusses the balance of genetic nature and the environmental impacts of nurture and learning in shaping migratory behavior--including how navigation during migration occurs. Finally, in Part TI.G, we describe the likely future directions of migration research, which are strongly affected by recent advances in technology. The body of knowledge outlined in this Part reveals variety among migratory species in virtually all aspects of migration, from its evolutionary beginnings, to the demographics of the individual migrants, to the manner and scale of the geographic movements of migration. Understanding the diversity encompassed by migratory species is necessary in order to develop and implement appropriate policies and management approaches for then conservation.

   Part III examines existing legal approaches to protection of biodiversity, broadly, to determine where there is support for conservation of migrations and migratory species. In acknowledgement of the number and diversity of laws, cases, and regulations, Part III is exemplary, rather than exhaustive--describing categories of laws, not enumerating individual laws. These categories are not mutually exclusive and serve to organize existing law, not to impose sharp distinctions. Part III.A considers possibilities for supporting conservation through funding and capacity building to many kinds of actors. Individuals and organizations vary considerably in their funding and training; by broadening and leveling the field, statutes and the programs they authorize advance what is possible in conservation of migratory species. Part III.A also discusses coordination and information exchange as means of capacity building. Part III.B focuses more narrowly on federal incentives for conservation at the state level. Most wildlife...