UNIVERSITY PARK, Pa. -- Right now, in the vast prairie pothole region of southern Canada and the United States' upper Midwest, waterfowl are mingling, raising their young and instinctively preparing to migrate, some leaving as early as August.
All spring and summer these wild birds -- known as puddle or dabbling ducks, such as gadwalls, mallards, pintails, teal and wigeons, to name a few -- have shared aquatic habitats, food supplies, brood-rearing responsibilities and likely something ominous -- avian flu.
When those ducks, acting on a primordial impulse, do head toward their wintering grounds, they will take different routes. By far, most will fly more or less due south, on the Mississippi Flyway, but many will embark east and then merge onto the Eastern Flyway. That route will take them over Pennsylvania, Maryland, Virginia, the Carolinas and Georgia to Florida's Gulf coast.
When they stop to rest and feed along the way, infected birds may potentially shed the pathogens that cause the highly contagious disease in their droppings and secretions.
"This strain of avian flu, H5N2 -- which has yet to be seen along the Eastern Flyway – usually doesn't make waterfowl sick, in fact many don't show any symptoms, and it doesn't affect people or other mammals," said Margaret Brittingham, professor of wildlife resources in Penn State's College of Agricultural Sciences.
"But it does sicken and kill other birds, namely domesticated chickens and turkeys. It has devastated the poultry industry in states such as Minnesota and Iowa along the Mississippi Flyway, and Washington and Oregon along the Western Flyway."
Two years ago, explained Brittingham -- a wildlife specialist with Penn State Extension -- migrating waterfowl carried a novel strain of avian flu out of Asia to breeding grounds in the Bering Sea region of northern Russia, and from there at least a few ducks are believed to have conveyed it to Alaska, where south-migrating birds brought it to the Pacific Northwest.
It somehow spread east from there.