Seeking Refuge: Birds and Landscapes of the Pacific Flyway

1. The Wetland Archipelago

16 The word “fly way” conjures up visions of an aerial highway that birds follow up and down the continent, taking rest stops along the way. But the word is misleading. There is no interstate in the sky for the birds to follow. Ornithologists realize that beneath the simplicity of the flyway concept lays a very complicated network of crisscrossing migration paths. Despite these limitations, wildlife managers still use flyways as a management tool. In the words of one nature writer, the Pacific Flyway is a “way of thinking about ducks.” 1 Although biologists now have more sophisticated understandings of bird migration than they did when the concept was developed in the 1930s, it does capture one basic fact of North American bird migration: along the Pacific coast, waterfowl migrate between the ocean and the flanks of the main mountain ranges. Birds can and do cross these mountains while migrating, but many species of waterfowl follow the general north-south trending ranges.2 Except for the northern part of the continent, where wetlands were extensive and plentiful, most of the area encompassed by the Pacific Flyway was useless to waterfowl even before people began draining 1 The Wetland Archipelago The Wetland Archipelago 17 wetlands on a large scale in the late nineteenth century. Ducks, geese, and swans need wetlands to survive, and the degree of their dependence varies by species. Most waterfowl nest on or near wetlands. Although birds migrate across vast distances, their journeys bring them to environments similar to ones they left. A goose would breed in a wetland in Alaska, stop to feed in a wetland in British Columbia or Oregon, and spend the winter in a wetland in California.3 Until the nineteenth century, people did not radically alter or drain wetlands along the Pacific Flyway on a large scale. This does not mean that they were pristine sites free from human use. The enormous productivity of wetland environments made them attractive to Native peoples from Alaska to Mexico. Although they had a significant impact on wildlife numbers using these wetlands, their technologies limited their ability to alter the hydrology of western marshes and estuaries. Native peoples neither diverted major rivers nor filled wetlands . Until the nineteenth century, the distribution of wetlands, and their formation or disappearance, was largely the product of natural forces.4 Yet the fact that humans had only minimal impact on the hydrology of western wetlands does not mean that these wetlands were timeless . Change defines the natural history of these places. Focusing on the wetlands just prior to their destruction in the nineteenth century can create a misleading impression of their characteristics. Wetlands were dynamic environments before people began to drain, dike, and fill them, and the degree of dynamism differed from area to area. This dynamism operated over short courses of a few years and over longer periods of centuries and millennia. During the Pleistocene, for example, ice covered most of the current breeding range of migratory waterfowl. Waterfowl were therefore geographically limited to regions south of the ice sheets that covered most of present-day Canada and Alaska. As the ice sheets retreated between 10,000 and 12,000 years ago, many areas were opened to colonization by plant species and, eventually, by migratory birds. Waterfowl migration is partially an adaptation to this change.5 By migrating, waterfowl and other birds were able to take advantage of the seasonal abundance of resources available in the Arctic and subarctic during the summer, and then retreat to lower latitudes 18 The Wetland Archipelago before the onset of winter. But long migratory journeys exposed them to dangers en route, as well as to the possibility that drought would dry up wetlands in either the wintering or breeding range. For many species of birds, migration was necessary and unavoidable, but it exacted a cost. The cost became all too apparent to conservationists hoping to save migratory waterfowl as western marshes and estuaries were lost to agricultural and urban development.6 The Pacific Flyway Waterscape Pacific Flyway birds annually migrated to wetlands separated by thousands of miles. Prior to the nineteenth century, wetlands were more common in the northern reaches of the flyway than in the southern portion, where aridity and topography restricted their development. Although wetlands and lakes were abundant in the Arctic and subarctic , they were not all equally useful for waterfowl. River deltas supported the highest numbers of waterfowl...