INTRODUCTION

Much of modern conservation biology concerns understanding the impact of past and/or ongoing environmental change on animal and plant populations. This work has many facets including, for example, diagnosing causes of population declines at various spatial scales and managing critically endangered populations (see Chapters 6–8). Increasingly, conservation biologists are being asked to look into the future and assess how populations might respond to future environmental change. In this respect, environmental change might include the activity or inactivity of conservationists themselves, large-scale changes in the environment such as global warming (see Houghton 1997 for a review, and Chapter 8), or the direct impact of human activities on the environment at various levels of scale, for example habitat loss and fragmentation (see Chapter 10).

To look into the future conservationists need predictive tools. Without predictive tools, debate about the impact of future environmental change becomes dominated by dogma. However, to inform debate conservationists need reliable predictive tools that allow them to quantify and assess the impacts of environmental change on important populations. In this chapter, we critically review predictive tools (ecological models) that are becoming increasingly used by conservationists for forecasting how populations might behave in the future, in the face of a broad range of environmental changes. The chapter is structured so that particular ecological models are outlined in principle, before detailing their application to various bird conservation problems. Next, the reliability of models is discussed and suggestions made about how they might be used appropriately.