Conservation of migratory species in a changing climate: strategic behavior and policy design.

• Author: Miller, Kathleen A.

1. INTRODUCTION II. CONCEPTS AND INSIGHTS FROM THE THEORY OF GAMES A. Harvesting Games B. Issues Related to Non-Harvested Migratory Species III. INSIGHTS FROM CASE ANALYSES A. North Pacific Fur Seals and Statecraft B. Atlantic Bluefin Tuna C. Eastern African Wildebeest Migration IV. CONCLUDING THOUGHTS I. INTRODUCTION

   In an increasingly human-dominated world, it may become ever more challenging to maintain the viability of migratory species and even more difficult to restore their populations to sufficient levels to support robust migrations "as phenomena of abundance." (1) As the Earth's human population continues to grow, (2) and as individuals strive to improve their living standards, there are likely to be new pressures to intensify agricultural exploitation or other human uses of the land and water on which migratory species rely. Such pressures could impair the ability of these systems to support animal migrations. (3) Climate change will create additional challenges, as warming temperatures and changing hydrologic regimes alter habitat characteristics, while potentially decoupling phenological relationships that play key roles in the dynamics of migratory populations. (4) Those same climatic changes will also affect the intensity of human demands on land and water resources by altering the potential productivity of agricultural lands and increasing demands for irrigation water to augment yields. (5)

   Following Professor Wilcove's explanation of the major anthropogenic threats to migrations," Professors Fischman and Hyman describe four broad categories of threats to animal migrations.' These are habitat destruction, overexploitation, human-created obstacles to migration, and climate change. (8) Each of these threats exists because humans have found it advantageous to engage in activities that cause the harm, whether harm was intended or not. (9) Habitat destruction, human-caused obstacles to migration, and anthropogenic climate change all result from a long sequence of private and public decisions taken in response to economic opportunities. Examples include the efforts of public entities to provide transportation improvements, (10) and water and energy services to support economic development. (11) Overexploitation, on the other hand, is more typically the direct outcome of a competitive race to exploit common property resources in the absence of effective institutional arrangements to constrain that race. Addressing these threats will require finding both the will and the way to alter the choices that imperil the vitality of animal migrations. Two types of human choices are relevant: 1) those that are directly focused on migratory animal conservation, including the development of conservation reserves, hunting laws, and land use regulations specifically tailored to protect animals and their migratory corridors; and 2) decisions made for other purposes that entail incidental or unintentional impacts on animals and their habitats. The focus, here, is primarily on the first category of decisions, but the outcome of any given conservation policy clearly depends on a whole suite of choices in both categories, made at different points in time by different parties. This Article focuses not on the behavior and ecology of migratory animals, but rather on the behavior and interactions of humans whose individual and collective actions could either assist or impair the survival and abundance of migratory animals in a changing climate.

   A central feature of the challenge of maintaining animal migrations is that effective conservation typically requires coordinated actions on the part of a variety of public and private entities. (12) These may include individual resource users or property owners, different government agencies within a single national or state jurisdiction, or the governments of different sovereign nations. No single entity has full control over the set of human actions that determine the fate of migrating animals and long-term protection of their migratory corridors. This creates an inherent interdependence among their conservation decisions--in other words, the success of actions taken by one entity depend very much on what other entities decide to do. (13)

   While altruism and dedication to environmental stewardship may motivate a certain level of willingness to engage in collective efforts of preserve animal migrations, each decision-making entity also is likely to care about the particular balance of benefits and costs it expects to incur as a result of the cooperative conservation project. The theory of games--or strategic optimization--can provide useful insights regarding the effects of such interdependence on individual decisions as well as on the conditions needed to induce successful coordination of conservation actions.

   Game theoretic concepts thus provide the backdrop for the following discussion of the human side of animal migration conservation. The questions to be faced include not only how to secure agreement on a desirable set of coordinated conservation actions, but also how to ensure that parties will actually carry out their obligations. A further challenge is how to ensure the continued workability of a coordinated conservation program in the face of changing conditions, including climate-driven environmental changes that might dramatically alter the effectiveness of a planned management strategy. Also relevant are socioeconomic changes that could alter the perceived net benefits of complying with an existing agreement.

2. CONCEPTS AND INSIGHTS FROM THE THEORY OF GAMES

   The theory of games describes the strategizing behavior of two or more decisionmakers when their options are characterized by mutual interdependence. (14) The decision makers are called "players" and they are assumed to be self interested--in other words, each is attempting to achieve the best outcome from that player's individual perspective. (15) Game theory has been argued to be

   the most important and useful tool in the analyst's kit whenever she confronts situations in which what counts as one agent's best action (for her) depends on expectations about what one or more other agents will do, and what counts as their best actions (for them) similarly depend on expectations about her. (16) In particular, mathematical models of game-playing behavior provide useful insights on how the structure of incentives inherent in a particular situation may affect the likelihood of achieving mutually satisfactory solutions to social problems. (17) By explicitly articulating the incentives facing each agent and analyzing the likely outcome of the sequence of actions and reactions available to them within the particular game setting, it becomes easier to identify how outcomes depend on the rules of play and the payoffs that a player expects to achieve from different courses of action. When the parties to a negotiation understand that dependence, they then may be able to conceive of ways to alter the structure of games in which they find themselves to achieve a superior outcome. (18)

   Indeed, in the context of international environmental agreements, Professor Barrett argues that "if they are to succeed, treaties must strategically manipulate the incentives states have to exploit the environment." (19) Specifically, Barrett notes that state sovereignty means that there is no external authority that can force a nation to enter into a treaty or abide by its terms, and as a result, international agreements must be "self-enforcing." (20) In practical terms, that means that it typically will be necessary to craft the terms of an agreement to make compliance the preferred strategy for each participant. (21) He thus describes "statecraft" as the art and science of changing the rules of the game to "improve on unilateralism and make every party better off." (22)

   The problem of assuring compliance with a mutually beneficial program of action is not unique to international environmental agreements. In the often-cited single-period "prisoner's dilemma" game the participants know that they will be better off if they cooperate with one another, but the rules of the game and the structure of the expected payoffs lead them inexorably to the outcome that nobody desires, with each choosing not to cooperate and thus each achieving a much lower payoff than could have been achieved if all participants had cooperated. (23) The inevitability of this outcome arises because the game is only played once. There is thus no opportunity for the players to develop mechanisms to reward one another for cooperation or to punish failures to cooperate. Even if the players in a one-shot prisoner's dilemma can communicate--and agree beforehand on what they will do--when the moment comes they are likely to break their word because none

   will trust the others to carry through, and each fears being played for a chump. (24) The only way to avoid that universally-undesired outcome is to introduce an enforcement mechanism that changes the structure of payoffs to make cooperation the best strategy for each player--in essence changing the prisoner's dilemma game into something else. (25)

   Fortunately, most of the policy coordination problems relevant to protecting animal migrations are not very much like a single-period prisoner's dilemma game. In particular, they do not involve one-shot interactions with strangers who one never expects to encounter again. Rather, the decision makers whose choices will determine the sustainability of robust animal migrations may be involved in long-term ongoing relationships with one another, perhaps encompassing a variety of interactions revolving around different functions and issues.

   Another difference between the policy setting for animal migration conservation and the prisoner's dilemma is that even unilateral conservation actions may, in some circumstances, yield considerable benefits to the parties undertaking those actions...