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Waterfowl Migration and Bird Identification Go Hand in Hand (April 2004) Spring is what I call "showtime for birds." The snows are melting and water is everywhere. And nothing is more showy or visible in the spring on a pond, lake, stream or river in Montana than colorful waterfowl. You don't have to walk or drive far to enjoy waterfowl this time of year. The term "waterfowl" pertains to ducks, geese and swans, which belong to a similarly related group of birds in the Order Anseriformes (Family Anatidae). In North America these birds are called waterfowl, whereas in Britain this same group of birds are called wildfowl. Waterfowl are not to be mistaken for shorebirds (such as sandpipers, plovers and snipe) or wading birds (such as herons, egrets and ibis). Members of this family have many characteristics in common, such as in ducks, most males or drakes possess brightly colored plumage and the females or hens (can also be called a duck) are more camouflaged with browns and grays so they can blend in with their environment when nesting. When geese and swans (and whistling-ducks, if you include warmer climates to the south) are in breeding plumage, the sexes are identical and can be told only by size (males being generally larger than females) and more scientifically by inverting and examining the cloaca through a technique known as cloacal sexing. I don't recommend cloacal sexing to the readers - it is a messy occupation. Anyway, the absence or presence of this small corkscrew penis-like appendage is a method of separating female from male waterfowl. Adding to your lexicon of terms, please remember that in geese a male is called a gander and a female a goose, whereas in swans the male is the cob and the female is the pen. Other characteristics waterfowl have in common include long necks, short tails, heavy bodies, relatively long wings, but most noticeable are large heads with flattened bills for securing food and webbed feet for swimming and takeoff.
Migration So why do birds migrate? Primarily due to the shortage of food. Most waterfowl - but not all - are long-distance migrants, and most depart their breeding range in the north to winter in the south. Since water is the lifeline of waterfowl, if it freezes then these birds have no choice but to migrate. The degree to which waterfowl migrate depends on the species. Cinnamon Teal, for instance, are some of the last waterfowl to arrive in Montana in the spring and some of the first to depart in the fall. They typically don't arrive until the third week in April and depart by mid-September. The reason for this short showing in Montana is they have a long way to go, mostly because they winter in interior marshes and coastal wetlands of Mexico. Since Cinnamon Teal are specialized filter feeders, they rely on shallow water areas rich in foods such as submerged aquatic plants and plant seeds. In the fall this habitat dries up and is nearly non-existent in Montana, hence it marks the migration of Cinnamon Teal to more reliable seasonal habitat in Mexico. On the other hand, resident Trumpeter Swans of the Greater Yellowstone are primarily sedentary in nature, moving only short distances from summer range to winter range due to the influence of geothermal water. Trumpeter Swans from the northern latitudes such as Alberta and Yukon, however, leave their summer range when the lakes freeze over and migrate to geothermal open water areas such as are found in the Greater Yellowstone in winter.
Get out and enjoy the spectacle Waterfowl this time of year are numerous, colorful and varied. But most importantly they are a good reason to get outside and enjoy this recreational playground we call the Big Sky. Now that the reader has a better idea from previous columns on choosing bird field identification books, setting up a winter bird feeder and witnessing bird migration, it's time to identify other birds. Bluebirds will be the feature topic of the May issue of the Big Sky Birding column. Enjoy! And the Best of Big Sky Birding to you!
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