Bird Ranges and Barriers - Page 1

With varied landscapes come varied resources. Different bird species need different resources; therefore they become limited to certain areas. We call the broad area a bird occupies a range. Knowledge of the range of a species will disclose whether you will see a particular species in your backyard at sometime during the year. It would be fruitless, for example, for a bird-watcher in Pennsylvania to sit by the window in hope of spotting a Steller's Jay. Although the Steller's Jay and its eastern cousin, the Blue Jay, appear similar in behavior and appearance, the Steller's Jay rarely ventures east of the Rocky Mountains, and the Blue Jay rarely roams west of them.

The mountains may be a barrier to the Blue Jay and the plains a barrier to the Steller's Jay. Other variables in the environment may serve as barriers to limit a species' range. Many land birds, for example, will not cross a large body of water; conversely many aquatic birds avoid large land areas.