Statutory reform to protect migrations as phenomena of abundance.

   I. Introduction  II. The Need for Law Reform to Protect Migrations as Phenomena      of Abundance      A. Three Case Studies of Migration         1. Red Knot         2. Pronghom Antelope         3. Monarch Butterfly      B. Why Is a Comprehensive Legal Approach Needed?      C. Shortcomings of Existing Federal Laws for Protecting         Migrations      D. What Would a New Migration Protection Law Offer?      E. What Migrations Would Benefit Least and Most from Law Reform III. Description of a Proposed Migration Protection Act      A. Findings and Purposes      B. Applicability      C. Legal Approaches for Listed Migrations      D. First Steps for Non-Listed Migrations IV. Conclusion 

I. INTRODUCTION

It's a wonderful thing that the American bison (Bison bison) managed, narrowly, to avoid extinction. We can see bison at Yellowstone, and in zoos, and that is good. We don't even have to go very far if we want to buy and eat bison meat. But the American bison, as it historically existed in the United States, is in fact gone. It no longer gathers in herds of thousands or moves across hundreds of miles of unbroken prairie, and it no longer shapes the ecological system that sustained it. (1) We have preserved the species, but we can only respond with wonder--we are indeed willing to do no more than wonder--at what the migration must have been.

Even so, there are other migrations that have thus far survived all of the development, borders, barriers, harvest, and habitat alterations we have thrown in then way. It may be that we are willing to make the necessary commitments so that those migrations might make our children, and ourselves, marvel. It may be that we are willing to do more than merely see that the species survives. It is worth hoping that we are willing to conserve the extraordinary natural spectacle, the ecological force, and the natural wonder of some species in full natural context: we may be willing to conserve migrations themselves, and in this article, we hope to enrich the discussion that has begun on that proposition.

We define migration simply as the cyclical, predictable, round-trip movement of the entire population, or any geographically separate part of the population of any species or subspecies of animals. (2) Ranging, dispersal, and certainly foraging are not "migration" for purposes of our discussion. (3) This broad and simplistic definition of migration suits our purpose in this article, which is to focus on the conservation of behaviors and processes related to the migration cycle. Such behaviors and processes may be part of the movement phase--active movement as well as stopover activities--or the stationary phase--e.g., breeding, nesting, and overwintering--of the migration cycle. In fact, we will frequently use the terms "migration" and "migration phenomena" as shorthand for all of the migration-related behaviors and processes exhibited by a particular population.

Our conceptual perspective in this article is that migration-related behaviors and processes are themselves phenomena worthy of protection, as a category of biodiversity. Lincoln Brower has employed the concept of an "endangered phenomenon" as an alternative to the predominant conservation paradigm, which focuses on diminishing species diversity, minimum viable populations, and the demise of habitats and populations that leads species to extinction. (4) Brower defined an endangered phenomenon as "a spectacular aspect of the life history of an animal or plant species involving large numbers of individuals that are threatened with impoverishment or demise; the species per se need not be in peril; rather, the phenomenon it exhibits is at stake," and he referred to the migration of the monarch butterfly as an example of such an endangered phenomenon. (5) Similarly, the monarch's winter roosts in Mexico and California were designated as threatened phenomena by the International Union for Conservation of Nature (IUCN) in 1983, reflecting the recognition that a migratory phenomenon can be imperiled even though the species as a whole is not in danger of extinction. (6) Professor David Wilcove's writings on migrations as "phenomena of abundance," (7) as well as Professors Fischman and Hyman's article on the legal components of migration protection, also rely on this theme of biological phenomena worthy of protection. (8) Most recently, David Quammen wrote about animal migration as awe inspiring and "a phenomenon far grander and more patterned than animal movement." (9) This perspective of migration as a "phenomenon" shines a spotlight on notable behaviors and processes, such as mass movements of animals, movements through ancient pathways, and mass aggregations at wintering, breeding, and stopover sites. Protecting such life-history phenomena adds to the biodiversity conservation agenda. (10)

Migration phenomena can provide ecological, psychological (e.g., aesthetic), cultural, and economic benefits. (11) Ecological benefits include seed dispersal, nutrient transport, and pollination. (12) In some instances, as was true in the case of the bison, migration shapes the landscape and thus, in some respects, the ecology of the areas in which it occurs. Additionally, the opportunity to observe large numbers of animals congregating or moving together has important cultural and psychological value to humans; images of salmon leaping over waterfalls on their way upriver, enormous "Vs" of Sandhill cranes (Grus canadensis) flying south in the fall, and whale pods plying coastal waters, are iconic. Imagine seeing, as some did as late as 1871 in southern Kansas, a herd of bison the main body of which was estimated to be fifty miles deep and twenty-five miles wide. (13) Some migrations in our country are part of our heritage not unlike properties that are protected by the National Historic Preservation Act. (14) Migrations and migratory species also provide economic benefits including harvest and sales of harvesting equipment, nature oriented tourism and recreation, and travel to the locations in which such activities can be pursued. (15) With the loss of migration phenomena comes the loss of values and benefits associated with those phenomena, even if the species itself is not in peril.

The migration-as-phenomenon perspective does not supplant the traditional paradigm of species-based conservation, and the two perspectives are complementary. Ensuring the existence of a species is essential for protecting the migration-related behaviors and processes that constitute the phenomena proclaimed by Brower, Wilcove, and Quammen as worthy of protection. On the flip side, for obligate migrants, ensuring the existence of the migration is essential for protecting the species. (16) In particular, protecting migrations while the species' populations are still relatively abundant, and the ecological, psychological, cultural, and economic benefits of migration are still forthcoming, is a proactive approach that can keep species from reaching the dire straits that requires emergency room intervention.

Furthermore, conserving any phase of a species's migration cycle as a phenomenon requires protecting the animals during all phases of the cycle--at the breeding grounds, at locations inhabited and used during other stationary phases, during movement, and at stopovers. For example, identifying and protecting the breeding and wintering grounds of migratory buds is clearly important to ensuring population persistence. (17) Yet migratory birds spend approximately 25%-33% of their annual cycle in transit between breeding and wintering areas, and survival challenges encountered on these journeys, including mortality at stopover sites, may be responsible for a majority of annual adult mortality in land birds. (18) In short, all phases of the migration cycle must be maintained to ensure that any one phase of the cycle persists.

Yet the traditional species-based perspective of conservation, with its focus on declines in abundance, rarity, reactive conservation actions, and minimum viable populations, is limited and will usually produce different priorities for conservation and scientific research than the migration-as-phenomenon perspective. (19) The species-based perspective focuses our attention first and foremost on the persistence of the species. The United States appears to have accepted the notion that the loss of species as compositional elements of biodiversity is a serious problem. (20) The concept of extinction is readily grasped. Certainly, as mentioned above, for those populations that must migrate to survive, conserving migratory behavior and avoiding population extinction are two sides of the same coin. A minimalist approach would seek merely to maintain the smallest number of individuals necessary to accomplish the migratory behavior and avoid extinction--the minimum viable migration or population. But the only benefits of migration maintained by this strategy, other than the survival of the species, are whatever benefits accrue from that minimum number of animals. The benefits of minimal populations may not include many of the ecological, psychological, cultural, and economic benefits associated with migration phenomena, which typically require higher abundances than minimum viable populations. This is why we speak of migration as a "phenomenon of abundance." (21) Thus, restoring and maintaining relatively high abundances--e.g., historic levels or carrying capacity--are conservation and research priorities for the migration-as-phenomenon perspective, but are not necessarily priorities for the species-based conservation perspective.

This Article presents an idea for a new federal law that reflects the perspective that conservation of migratory behaviors and processes as phenomena of value in and of themselves, and not only of value for species persistence, can provide unique and important benefits. Such a perspective would fill a gap in the existing scheme of conservation laws. Existing conservation policy generally serves the species-based conservation perspective and, with the notable exception of laws targeting North American waterfowl and marine mammals, is not designed and implemented to effectively protect the benefits and values of abundant animal migrations. The Endangered Species Act (ESA), (22) the Migratory Bird Treaty Act (MBTA), (23) and the 1979 Convention on the Conservation of Migratory Species of Wild Animals (Bonn Convention), (24) while offering protections for species that migrate, are not fundamentally concerned with protecting the functional benefits and values derived from the process of migration. Rather, these laws are generally concerned with protecting the benefits that flow from the existence of the species populations, and deal with cross-boundary movements because dealing with the movements is necessary for the species conservation purpose. (25) If migratory populations could be better conserved by reducing or eliminating the migratory behavior, the purposes of these laws, which generally are to prevent scarcity and extinction, would still be served.

Our proposed federal law to protect migrations as phenomena of abundance would authorize a comprehensive set of legal tools, including both carrots and sticks, applied to a limited set of nationally or regionally "significant" or "important" migrations. To be sure, such a comprehensive approach is a worthy long-term goal for all migratory populations--including, for example, populations of songbirds, (26) tree bats, (27) turtles, (28) fishes, (29) and insects (30)--regardless of their national or regional "significance." Migratory animals are especially vulnerable to a variety of threats because they are exposed to multiple ecosystems and jurisdictions, tend to congregate in large numbers in discrete and often vulnerable areas, and require a large amount of fuel for then long-distance movements. (31) In terms of the benefits of migration mentioned above, many of the migratory populations that currently may lack national or regional significance serve important ecological roles at local geographic scales and are highly valued by one or another subset of the public for scientific or other reasons. By focusing on a limited set of nationally and regionally significant migrations, however, we stand a reasonable chance of having the law introduced into Congress. (32) If such a law were enacted, we could use it to learn about the costs and benefits likely to result from applying various mixtures of legal approaches to migration protection in general. (33)

Part II argues that a new and comprehensive federal law to protect nationally or regionally significant migrations as phenomena of abundance is needed. The existing fragmented framework of laws and authorities is insufficient to protect most migratory populations against a diversity of threats across multiple jurisdictions and broad geographic scales. Part II.A sets out three migration stories--the rufa subspecies of the American Red Knot (Calidris canutus), the Grand Teton population of the pronghorn antelope (Antilocapra americana), and the eastern North American population of the monarch butterfly (Danaus plexippus)--that will be used to explore and illustrate our ideas for law reform geared toward protecting migrations. Part II.B examines why a migration law should authorize and apply a comprehensive set of legal approaches. Part II.C summarizes the shortcomings of existing conservation laws for protecting migrations as phenomena of abundance. In Part II.D, we examine how a migration protection law might have advanced the conservation of the case-study populations over what has occurred to date, and how it might contribute to their conservation in the future. Finally, in Part II.E, we point out, as a caveat, that some migratory populations would not likely benefit from a new law at this time.

Part III then outlines the central elements of our proposal for a federal migration protection law. We first consider the purposes of such a law in Part III.A, and in Part III.B we suggest alternative methods for nominating and listing "nationally or regionally significant" migrations. We also suggest criteria for selecting such migrations. Part III.C reviews the legal approaches most useful for our proposed law as a function of the health of the listed migration. Then, in Part III.D, we briefly outline some first steps toward conserving the many migrations not likely to be deemed "significant" and thus not covered by the comprehensive approach applied to "significant" migrations.

II. THE NEED FOR LAW REFORM TO PROTECT MIGRATIONS AS PHENOMENA OF ABUNDANCE

Several United States statutes and international agreements have been set in place to conserve species that migrate. For example, statutes include the MBTA and Marine Mammal Protection Act (MMPA), (34) mentioned above, as well as the Migratory Bird Conservation Act, (35) Neotropical Migratory Bud Conservation Act, (36) Marine Turtle Conservation Act, (37) and North Pacific Anadromous Stocks Act. (38) International agreements include the Interim American Convention for the Protection and Conservation of Sea Turtles, (39) the bilateral Migratory Bird Treaties, (40) and the Convention on the Conservation and Management of Highly Migratory Fish Stocks in the Western and Central Pacific Ocean. (41) These statutes and agreements as well as others have spawned multiple programs and initiatives for migratory species, such as the Migratory Bird Program, (42) North American Waterfowl Management Plan, (43) United States Shorebird Conservation Plan, (44) North American Waterbird Conservation Plan, (45) Partners in Flight, (46) the North American Bird Conservation Initiative, (47) Western Hemisphere Shorebird Reserve Network, (48) Western Hemisphere Migratory Species Initiative, (49) and Wildlife Without Borders. (50)

Several of these laws and management initiatives have at least the potential to protect some migratory populations at relatively high abundances. In particular, an objective of the MMPA is to restore and maintain marine mammals at "optimum sustainable" levels. (51) Unlike the MMPA, the MBTA does not specify any objective for population abundance, but neither does it contain on its face any limit on abundance, so the MBTA could be used to maintain migratory bird populations at historic abundances if that target were politically and ecologically feasible. (52)

Yet, as we point out in this Part, even these laws are inadequate as templates for the kind of law that is needed to conserve migratory populations and the benefits derived from their migrations. Although these laws may address the need to maintain abundances above minimum viable levels, they attempt to achieve the desired results by relying primarily on limited and not very flexible legal approaches. In this Part we examine the need for a new migration protection law that employs a range of legal approaches to address the diversity of threats that migratory populations face. To assist in that task, we reflect upon the stories of three migratory populations that are nationally well known.

A. Three Case Studies of Migration

Throughout this Part we use three case studies to explain and justify the need for law reform to protect migration phenomena: the rufa subspecies of the American Red Knot (Caladris canutus rufa), a shorebird that has been declining due in part to reductions in its food supply, horseshoe crab eggs, at its main stopover site at Delaware Bay; a population of about 200 pronghorn antelope (Antilocapra americana) that summers in Grand Teton National Park and which faces obstacles along its ancient 170-mile migratory corridor between the Tetons and its winter range in the Upper Green River basin in western Wyoming; and the eastern North American population of 100-500 million monarch butterflies (Danaus plexippus), which overwinter in dense clusters on the boughs and trunks of fir trees at a handful of high-elevation sites in a small area of central Mexico. AU three populations are currently recipients of varied conservation efforts. The primary threat for the Red Knot, the pronghorn, and the monarch populations occur during the stopover, movement, and overwintering stage, respectively, but impacts at other stages of the migration cycle also threaten these migratory populations.

1. Red Knot

The accounts of the rufa Red Knot frequently begin with a statement of wonder at the 30,000-kilometer annual migration, "one of the longest-distance migrations in the animal kingdom." (53) Red Knots, which are "jump migrants," fly thousands of kilometers without stopping: a large part of the population breeds in the Canadian Arctic and winters in South America. (54) Although Red Knots spread across a large area of the Arctic during the breeding season, for the rest of the year they occur mainly in large flocks at a limited number of key coastal sites. (55) The Delaware Bay area (in Delaware and New Jersey) is the final known spring migration stopover on the journey north. (56) The Red Knots concentrate in the Delaware Bay area from the middle of May to early June, corresponding to the spawning season of horseshoe crabs (Limulus polyphemus). (57) The Knots feed on horseshoe crab eggs, rebuilding energy reserves needed to complete the migration to the Arctic and arrive on the breeding grounds in good …

Statutory reform to protect migrations as phenomena of abundance.

   I. Introduction  II. The Need for Law Reform to Protect Migrations as Phenomena      of Abundance      A. Three Case Studies of Migration         1. Red Knot         2. Pronghom Antelope         3. Monarch Butterfly      B. Why Is a Comprehensive Legal Approach Needed?      C. Shortcomings of Existing Federal Laws for Protecting         Migrations      D. What Would a New Migration Protection Law Offer?      E. What Migrations Would Benefit Least and Most from Law Reform III. Description of a Proposed Migration Protection Act      A. Findings and Purposes      B. Applicability      C. Legal Approaches for Listed Migrations      D. First Steps for Non-Listed Migrations IV. Conclusion 

I. INTRODUCTION

It's a wonderful thing that the American bison (Bison bison) managed, narrowly, to avoid extinction. We can see bison at Yellowstone, and in zoos, and that is good. We don't even have to go very far if we want to buy and eat bison meat. But the American bison, as it historically existed in the United States, is in fact gone. It no longer gathers in herds of thousands or moves across hundreds of miles of unbroken prairie, and it no longer shapes the ecological system that sustained it. (1) We have preserved the species, but we can only respond with wonder--we are indeed willing to do no more than wonder--at what the migration must have been.

Even so, there are other migrations that have thus far survived all of the development, borders, barriers, harvest, and habitat alterations we have thrown in then way. It may be that we are willing to make the necessary commitments so that those migrations might make our children, and ourselves, marvel. It may be that we are willing to do more than merely see that the species survives. It is worth hoping that we are willing to conserve the extraordinary natural spectacle, the ecological force, and the natural wonder of some species in full natural context: we may be willing to conserve migrations themselves, and in this article, we hope to enrich the discussion that has begun on that proposition.

We define migration simply as the cyclical, predictable, round-trip movement of the entire population, or any geographically separate part of the population of any species or subspecies of animals. (2) Ranging, dispersal, and certainly foraging are not "migration" for purposes of our discussion. (3) This broad and simplistic definition of migration suits our purpose in this article, which is to focus on the conservation of behaviors and processes related to the migration cycle. Such behaviors and processes may be part of the movement phase--active movement as well as stopover activities--or the stationary phase--e.g., breeding, nesting, and overwintering--of the migration cycle. In fact, we will frequently use the terms "migration" and "migration phenomena" as shorthand for all of the migration-related behaviors and processes exhibited by a particular population.

Our conceptual perspective in this article is that migration-related behaviors and processes are themselves phenomena worthy of protection, as a category of biodiversity. Lincoln Brower has employed the concept of an "endangered phenomenon" as an alternative to the predominant conservation paradigm, which focuses on diminishing species diversity, minimum viable populations, and the demise of habitats and populations that leads species to extinction. (4) Brower defined an endangered phenomenon as "a spectacular aspect of the life history of an animal or plant species involving large numbers of individuals that are threatened with impoverishment or demise; the species per se need not be in peril; rather, the phenomenon it exhibits is at stake," and he referred to the migration of the monarch butterfly as an example of such an endangered phenomenon. (5) Similarly, the monarch's winter roosts in Mexico and California were designated as threatened phenomena by the International Union for Conservation of Nature (IUCN) in 1983, reflecting the recognition that a migratory phenomenon can be imperiled even though the species as a whole is not in danger of extinction. (6) Professor David Wilcove's writings on migrations as "phenomena of abundance," (7) as well as Professors Fischman and Hyman's article on the legal components of migration protection, also rely on this theme of biological phenomena worthy of protection. (8) Most recently, David Quammen wrote about animal migration as awe inspiring and "a phenomenon far grander and more patterned than animal movement." (9) This perspective of migration as a "phenomenon" shines a spotlight on notable behaviors and processes, such as mass movements of animals, movements through ancient pathways, and mass aggregations at wintering, breeding, and stopover sites. Protecting such life-history phenomena adds to the biodiversity conservation agenda. (10)

Migration phenomena can provide ecological, psychological (e.g., aesthetic), cultural, and economic benefits. (11) Ecological benefits include seed dispersal, nutrient transport, and pollination. (12) In some instances, as was true in the case of the bison, migration shapes the landscape and thus, in some respects, the ecology of the areas in which it occurs. Additionally, the opportunity to observe large numbers of animals congregating or moving together has important cultural and psychological value to humans; images of salmon leaping over waterfalls on their way upriver, enormous "Vs" of Sandhill cranes (Grus canadensis) flying south in the fall, and whale pods plying coastal waters, are iconic. Imagine seeing, as some did as late as 1871 in southern Kansas, a herd of bison the main body of which was estimated to be fifty miles deep and twenty-five miles wide. (13) Some migrations in our country are part of our heritage not unlike properties that are protected by the National Historic Preservation Act. (14) Migrations and migratory species also provide economic benefits including harvest and sales of harvesting equipment, nature oriented tourism and recreation, and travel to the locations in which such activities can be pursued. (15) With the loss of migration phenomena comes the loss of values and benefits associated with those phenomena, even if the species itself is not in peril.

The migration-as-phenomenon perspective does not supplant the traditional paradigm of species-based conservation, and the two perspectives are complementary. Ensuring the existence of a species is essential for protecting the migration-related behaviors and processes that constitute the phenomena proclaimed by Brower, Wilcove, and Quammen as worthy of protection. On the flip side, for obligate migrants, ensuring the existence of the migration is essential for protecting the species. (16) In particular, protecting migrations while the species' populations are still relatively abundant, and the ecological, psychological, cultural, and economic benefits of migration are still forthcoming, is a proactive approach that can keep species from reaching the dire straits that requires emergency room intervention.

Furthermore, conserving any phase of a species's migration cycle as a phenomenon requires protecting the animals during all phases of the cycle--at the breeding grounds, at locations inhabited and used during other stationary phases, during movement, and at stopovers. For example, identifying and protecting the breeding and wintering grounds of migratory buds is clearly important to ensuring population persistence. (17) Yet migratory birds spend approximately 25%-33% of their annual cycle in transit between breeding and wintering areas, and survival challenges encountered on these journeys, including mortality at stopover sites, may be responsible for a majority of annual adult mortality in land birds. (18) In short, all phases of the migration cycle must be maintained to ensure that any one phase of the cycle persists.

Yet the traditional species-based perspective of conservation, with its focus on declines in abundance, rarity, reactive conservation actions, and minimum viable populations, is limited and will usually produce different priorities for conservation and scientific research than the migration-as-phenomenon perspective. (19) The species-based perspective focuses our attention first and foremost on the persistence of the species. The United States appears to have accepted the notion that the loss of species as compositional elements of biodiversity is a serious problem. (20) The concept of extinction is readily grasped. Certainly, as mentioned above, for those populations that must migrate to survive, conserving migratory behavior and avoiding population extinction are two sides of the same coin. A minimalist approach would seek merely to maintain the smallest number of individuals necessary to accomplish the migratory behavior and avoid extinction--the minimum viable migration or population. But the only benefits of migration maintained by this strategy, other than the survival of the species, are whatever benefits accrue from that minimum number of animals. The benefits of minimal populations may not include many of the ecological, psychological, cultural, and economic benefits associated with migration phenomena, which typically require higher abundances than minimum viable populations. This is why we speak of migration as a "phenomenon of abundance." (21) Thus, restoring and maintaining relatively high abundances--e.g., historic levels or carrying capacity--are conservation and research priorities for the migration-as-phenomenon perspective, but are not necessarily priorities for the species-based conservation perspective.

This Article presents an idea for a new federal law that reflects the perspective that conservation of migratory behaviors and processes as phenomena of value in and of themselves, and not only of value for species persistence, can provide unique and important benefits. Such a perspective would fill a gap in the existing scheme of conservation laws. Existing conservation policy generally serves the species-based conservation perspective and, with the notable exception of laws targeting North American waterfowl and marine mammals, is not designed and implemented to effectively protect the benefits and values of abundant animal migrations. The Endangered Species Act (ESA), (22) the Migratory Bird Treaty Act (MBTA), (23) and the 1979 Convention on the Conservation of Migratory Species of Wild Animals (Bonn Convention), (24) while offering protections for species that migrate, are not fundamentally concerned with protecting the functional benefits and values derived from the process of migration. Rather, these laws are generally concerned with protecting the benefits that flow from the existence of the species populations, and deal with cross-boundary movements because dealing with the movements is necessary for the species conservation purpose. (25) If migratory populations could be better conserved by reducing or eliminating the migratory behavior, the purposes of these laws, which generally are to prevent scarcity and extinction, would still be served.

Our proposed federal law to protect migrations as phenomena of abundance would authorize a comprehensive set of legal tools, including both carrots and sticks, applied to a limited set of nationally or regionally "significant" or "important" migrations. To be sure, such a comprehensive approach is a worthy long-term goal for all migratory populations--including, for example, populations of songbirds, (26) tree bats, (27) turtles, (28) fishes, (29) and insects (30)--regardless of their national or regional "significance." Migratory animals are especially vulnerable to a variety of threats because they are exposed to multiple ecosystems and jurisdictions, tend to congregate in large numbers in discrete and often vulnerable areas, and require a large amount of fuel for then long-distance movements. (31) In terms of the benefits of migration mentioned above, many of the migratory populations that currently may lack national or regional significance serve important ecological roles at local geographic scales and are highly valued by one or another subset of the public for scientific or other reasons. By focusing on a limited set of nationally and regionally significant migrations, however, we stand a reasonable chance of having the law introduced into Congress. (32) If such a law were enacted, we could use it to learn about the costs and benefits likely to result from applying various mixtures of legal approaches to migration protection in general. (33)

Part II argues that a new and comprehensive federal law to protect nationally or regionally significant migrations as phenomena of abundance is needed. The existing fragmented framework of laws and authorities is insufficient to protect most migratory populations against a diversity of threats across multiple jurisdictions and broad geographic scales. Part II.A sets out three migration stories--the rufa subspecies of the American Red Knot (Calidris canutus), the Grand Teton population of the pronghorn antelope (Antilocapra americana), and the eastern North American population of the monarch butterfly (Danaus plexippus)--that will be used to explore and illustrate our ideas for law reform geared toward protecting migrations. Part II.B examines why a migration law should authorize and apply a comprehensive set of legal approaches. Part II.C summarizes the shortcomings of existing conservation laws for protecting migrations as phenomena of abundance. In Part II.D, we examine how a migration protection law might have advanced the conservation of the case-study populations over what has occurred to date, and how it might contribute to their conservation in the future. Finally, in Part II.E, we point out, as a caveat, that some migratory populations would not likely benefit from a new law at this time.

Part III then outlines the central elements of our proposal for a federal migration protection law. We first consider the purposes of such a law in Part III.A, and in Part III.B we suggest alternative methods for nominating and listing "nationally or regionally significant" migrations. We also suggest criteria for selecting such migrations. Part III.C reviews the legal approaches most useful for our proposed law as a function of the health of the listed migration. Then, in Part III.D, we briefly outline some first steps toward conserving the many migrations not likely to be deemed "significant" and thus not covered by the comprehensive approach applied to "significant" migrations.

II. THE NEED FOR LAW REFORM TO PROTECT MIGRATIONS AS PHENOMENA OF ABUNDANCE

Several United States statutes and international agreements have been set in place to conserve species that migrate. For example, statutes include the MBTA and Marine Mammal Protection Act (MMPA), (34) mentioned above, as well as the Migratory Bird Conservation Act, (35) Neotropical Migratory Bud Conservation Act, (36) Marine Turtle Conservation Act, (37) and North Pacific Anadromous Stocks Act. (38) International agreements include the Interim American Convention for the Protection and Conservation of Sea Turtles, (39) the bilateral Migratory Bird Treaties, (40) and the Convention on the Conservation and Management of Highly Migratory Fish Stocks in the Western and Central Pacific Ocean. (41) These statutes and agreements as well as others have spawned multiple programs and initiatives for migratory species, such as the Migratory Bird Program, (42) North American Waterfowl Management Plan, (43) United States Shorebird Conservation Plan, (44) North American Waterbird Conservation Plan, (45) Partners in Flight, (46) the North American Bird Conservation Initiative, (47) Western Hemisphere Shorebird Reserve Network, (48) Western Hemisphere Migratory Species Initiative, (49) and Wildlife Without Borders. (50)

Several of these laws and management initiatives have at least the potential to protect some migratory populations at relatively high abundances. In particular, an objective of the MMPA is to restore and maintain marine mammals at "optimum sustainable" levels. (51) Unlike the MMPA, the MBTA does not specify any objective for population abundance, but neither does it contain on its face any limit on abundance, so the MBTA could be used to maintain migratory bird populations at historic abundances if that target were politically and ecologically feasible. (52)

Yet, as we point out in this Part, even these laws are inadequate as templates for the kind of law that is needed to conserve migratory populations and the benefits derived from their migrations. Although these laws may address the need to maintain abundances above minimum viable levels, they attempt to achieve the desired results by relying primarily on limited and not very flexible legal approaches. In this Part we examine the need for a new migration protection law that employs a range of legal approaches to address the diversity of threats that migratory populations face. To assist in that task, we reflect upon the stories of three migratory populations that are nationally well known.

A. Three Case Studies of Migration

Throughout this Part we use three case studies to explain and justify the need for law reform to protect migration phenomena: the rufa subspecies of the American Red Knot (Caladris canutus rufa), a shorebird that has been declining due in part to reductions in its food supply, horseshoe crab eggs, at its main stopover site at Delaware Bay; a population of about 200 pronghorn antelope (Antilocapra americana) that summers in Grand Teton National Park and which faces obstacles along its ancient 170-mile migratory corridor between the Tetons and its winter range in the Upper Green River basin in western Wyoming; and the eastern North American population of 100-500 million monarch butterflies (Danaus plexippus), which overwinter in dense clusters on the boughs and trunks of fir trees at a handful of high-elevation sites in a small area of central Mexico. AU three populations are currently recipients of varied conservation efforts. The primary threat for the Red Knot, the pronghorn, and the monarch populations occur during the stopover, movement, and overwintering stage, respectively, but impacts at other stages of the migration cycle also threaten these migratory populations.

1. Red Knot

The accounts of the rufa Red Knot frequently begin with a statement of wonder at the 30,000-kilometer annual migration, "one of the longest-distance migrations in the animal kingdom." (53) Red Knots, which are "jump migrants," fly thousands of kilometers without stopping: a large part of the population breeds in the Canadian Arctic and winters in South America. (54) Although Red Knots spread across a large area of the Arctic during the breeding season, for the rest of the year they occur mainly in large flocks at a limited number of key coastal sites. (55) The Delaware Bay area (in Delaware and New Jersey) is the final known spring migration stopover on the journey north. (56) The Red Knots concentrate in the Delaware Bay area from the middle of May to early June, corresponding to the spawning season of horseshoe crabs (Limulus polyphemus). (57) The Knots feed on horseshoe crab eggs, rebuilding energy reserves needed to complete the migration to the Arctic and arrive on the breeding grounds in good …