The Song of the Dodo

Introduction: The Threat of Fragmented Habitats

Imagine taking a large, beautiful Persian carpet and cutting it into thirty-six small rectangles. While you still have the same total amount of fabric, you no longer have a carpet. You have three dozen ragged fragments that are quickly coming apart at the edges. David Quammen suggests this is exactly what happens when we break up natural landscapes. An ecosystem is a complex tapestry of relationships between plants and animals, and when it is chopped into isolated sections, the entire system begins to unravel.

This process of decline is known by several names among scientists, such as faunal collapse or relaxation to equilibrium. Thomas E. Lovejoy uses the term ecosystem decay to describe how a fragmented environment loses its variety of life over time, much like a radioactive element loses its mass. When a forest or habitat is isolated, species begin to disappear steadily and quietly. While many people are aware of individual endangered animals, few realize that the physical shrinking and splitting of habitats triggers a predictable, inevitable slide toward extinction for the entire community of life within them.

Biogeography is the study of where plants and animals live, and perhaps more importantly, why they are found in some places but not others. On the island of Madagascar, a bird once lived that stood ten feet tall and weighed a thousand pounds. This was the Aepyornis maximus, a creature that existed only on that single island until humans arrived a few millennia ago and transformed the ecosystem. Today, it exists nowhere, demonstrating how vulnerable isolated species can be to sudden changes.

Similarly, the tiny island of Bali once had its own unique subspecies of tiger, while the neighboring island of Lombok, separated by only twenty miles of water, never had tigers at all. These patterns of presence and absence are the core puzzles of the field. When this study focuses specifically on islands, it becomes island biogeography, a discipline that reveals nature at its most unconventional. Islands act as natural laboratories for evolution, producing unique creatures like pygmy hippos, giant tortoises, and chameleons no bigger than a human thumb.