The basic relationship of a bird to its home begins with the ecosystem in which it lives. We call an area that has a common structural framework an ecosystem. Ecosystems encompass soil and water as well as plants and animals. We characterize and name most ecosystems after the most conspicuous plants in the ecosystem.

North America contains a variety of ecosystems. Each has unique characteristic and an avifauna that is more or less unique to it. Each also shares some plants and animals -- including birds -- with other ecosystems.

Some bird species become restricted to a single ecosystem because they specialize in using the resources of that ecosystem. For example, the Greater Prairie-Chicken has become restricted to the prairie ecosystem of Texas; only an environment that contains a specific type of native grass provides suitable feeding and nesting areas.

The Red-cockaded Woodpecker gets restricted to the mature pine forest ecosystem of the southeastern United States; It specialized to the point that it will only feed and nest there. In contrast, some species, such as the Brown-headed Cowbird and Blue Jay, inhabit a number of ecosystems. We call these birds generalists; although they can live in a variety of habitats, they have really become "masters" of none. They could not compete well with the specialists for resources, but as generalists, they can turn to other foods and nest sites.