There are several hypotheses that may explain why waterfowl undertake molt migrations to the boreal forest and Arctic. One possibility is that the abundance of suitable, drought-resistant wetlands in the north provides molt migrants with greater access to food, which also tends to peak when these visitors arrive. In addition, with up to 24 hours of daylight in far northern latitudes, the birds have more time to forage, which might enable them to increase their daily nutritional intake.
Although waterfowl underwent molt migrations long before people arrived on the prairies and other southern breeding areas, many of the remote northern wetlands used by molting waterfowl remain pristine and largely undisturbed by people. Human disturbance can be extremely disruptive to flightless molting waterfowl, reducing foraging time, increasing energy expenditure, and potentially decreasing survival. As a result, we must ensure that land-use changes now occurring in the boreal forest and the Arctic do not negatively impact molting waterfowl and their fragile wetland habitats.
Mark Baschuk is a biologist and Dr. Stuart Slattery is a research scientist with the Institute for Wetland and Waterfowl Research at DU Canada headquarters at Oak Hammock Marsh.
Tell-Tail Feathers The natal down, characteristic of young waterfowl, is replaced by feathers weeks after hatching, depending on the species. When these first feathers form, some of the down may remain at the tips of the new feathers (far left). Often this downy tip will break off, forming a notched feather (center) that is commonly found in the tail feathers, or retrices, of birds. This characteristic can be used by biologists and hunters alike to determine a bird's age. A young-of-the-year bird will contain the downy tip or notch, whereas an adult bird will have fully formed feathers (right). These characteristic retrices of young birds are only present until late fall, when the juvenile retrices are molted and replaced with feathers lacking a notch.