The autumnal equinox is on September 21 this year. Of course, when fall rolls around in North Dakota, the thoughts of birds migrating — particularly waterfowl — often come to mind.
Migration is energetically expensive. Some birds have had to store up large amounts of fat to make the trip south. For some birds, it will be a non-stop trip, while others will need to stop occasionally to stoke their biological furnaces.
There is also considerable risk associated with migrating, including predation, collisions, and storms. As you might conclude, not all the birds will complete the trip. Plus, habitat loss and degradation of their wintering grounds may prove fatal or result in considerable stress.
Different species run on different schedules. Some shorebirds, for example, probably started their migration back in July, while the warblers may have started south during August. And some birds will not head south until a lack of food forces them to move on.
But it is the sights and sounds of waterfowl overhead that perhaps best characterizes the fall migrations. Who can resist pausing for a few moments when they hear or see a flock of cackling snow geese heading south? The guttural gurgle of sandhill cranes high above or the hooting of tundra swans overhead often elicit a similar response.
When it comes to waterfowl migrations, we are reminded that a species is usually composed of several populations. Biologists have come to recognize four migration corridors or flyways for waterfowl: The Atlantic, Mississippi, Central (which includes North Dakota), and Pacific flyways. Although it is a rather broad generalization, it helps waterfowl managers better manage the populations of geese, swans, and cranes that migrate in family groups. It is less useful with many other bird species.
So, take the time this fall to get out and do some bird watching before many of the migratory birds have left for warmer climes. There are plenty of areas to observe the birds, perhaps starting with your own backyard. And, of course, state and local parks and national wildlife refuges may be nearby and provide some interesting sights.
