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The Ridgefield National Wildlife Refuge provides a variety of habitats for many species of birds. 
The
refuge wetlands, croplands, and natural floodplains provide habitat
that supports over 220 species
of birds. The refuge hosts thousands of migratory
birds that fly from their breeding grounds in Arctic Canada and
Alaska to their wintering grounds in Baja California or South America,
a route known as the Pacific
Flyway. The areas of wetland habitat along the lower Columbia
River, including the refuge, are vital to the flyway. top of page In general, a migration pattern is from southern wintering grounds to northern nesting areas and back again in a year's time. Virtually all waterfowl migrate. There are several theories as to why waterfowl migrate, but the decreased availability of food and water as the seasons change is probably the most important reason. Birds use many techniques to guide them in the right direction during migration. They recognize landmarks, follow weather patterns, sense the magnetic field of the earth (for direction), and follow strong inherited instincts. Several senses and adaptations enable birds to migrate. Most migratory birds have very powerful flight muscles. Like most birds, they also have a highly developed respiratory system, hollow bones, internal air sacs, and specialized body shapes. All of these features enable them to fly high, fast, and for long periods of time. top of page Times of annual migrations are not the same for all birds. 
Shorebirds begin their fall migration in early July, but other species, such as geese, do not begin until late fall. Some birds have a leisurely migration, while others fly swiftly to their destinations. Migrating waterfowl begin to arrive at the refuge in late September, with the overall peak of migration in November. The newly flooded wetlands, sloughs, and fields provide plenty of winter food, loafing areas, and protection for these migrating birds. Many of them, especially Canada geese, spend the winter here, while others simply pass through to winter in areas further south. Migration north
begins in March as wintering birds begin to leave the refuge and
are replaced by other birds moving through the refuge from their
wintering areas to the south. Most geese are gone by mid-April;
most of the ducks are gone a few weeks later. Some ducks such as
mallards and cinnamon teal stay in the area during the summer to
nest and rear their young. Birds using the refuge are specifically adapted to the type of food they eat and the type of habitat they occupy. Many of the adaptations take the form of beak and feet modifications. Different species of birds usually do not compete for the same food. For example, birds in wetland habitats, though often feeding together, are not looking for the same food. One species may have a long bill that probes deep into the mud, while another species may have long legs that allow it to feed in deeper water.
top of page Wetland birds can be loosely divided into four groups based on their food preferences.
As lakes and ponds dry out in late summer, longer-legged birds such as great blue herons and great egrets are seen in groups feeding on fish, frogs, snails, and invertebrates that are concentrated in the shrinking bodies of water. At the same time, long-billed dowitchers and yellowlegs make use of the shallower water along the shoreline. Their long legs keep them above the water, while their long beaks probe for food in the mud. On higher land among grassy vegetation, nests of mallards and cinnamon teal are found. Great blue herons make their nests in trees, and wood ducks and hooded mergansers nest in tree cavities along the sloughs. The refuge supports a wide variety of birds, all of which need the habitats the refuge manages and protects. Try these classroom and field trip activities to learn more about the birds of the refuge.
Bird Matching Game: Can you match the bird's song to its picture? (requires
Flash) top of page Learn more about the birds of the refuge! Ridgefield National Widlife refuge: Oaks to Wetlands Adventure Field Guides Wilson Cady Guide to Ridgefield National Wildlife Refuge Washington Ornithological Society Visit the other learning stations in the Birds of the Refuge field trip. |
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