By Chuck Petrie
Warmer autumns and winters in recent years, habitat changes, and new food sources are affecting duck distribution as well as waterfowling opportunities
Ducks migrating south in winter aren't unlike hordes of college kids heading out on spring break.
The vacationing scholars seek unlimited rations of cold beer, warm beaches, fast tans, and brief dalliances with members of the opposite sex. To accomplish these lofty goals, some students travel to the customary venues: Daytona Beach, Ft. Lauderdale, and San Padre Island. Others, the trendsetters, seek out newer, more stylish outposts in the sun, however near or far their usually meager travel budgets allow (and wherever tattoo and body-piercing services are available).
When they stumble onto a rich new territory, their cohorts eventually follow in droves.
Ducks, in comparison, head south in search of copious rations of food, places where sunshine at least keeps water in a liquid state, and seasonal relationships (admittedly short, but somewhat longer and more meaningful than those of their collegiate counterparts) with members of the opposite sex. Like the kids, too, some birds frequent traditional wintering areas, while others pioneer new territories. When these explorers happen upon new, exploitable habitats, their cohorts also eventually follow in droves.
In the Atlantic Flyway, for instance, old-time duck hangouts such as Back Bay, Virginia; Albemarle and Pamlico sounds in North Carolina; and the DelMarva region's Chesapeake Bay still winter ducks, but not the quantities they did in days of yore. East Coast waterfowl hunters know this only too well.
Hurricane damage to shallow- water feeding areas and other forms of habitat degradation are major reasons for declines in duck visitations to these waters.
On Chesapeake Bay, as an example, water quality declines have affected the habitat to the point that many canvasbacks that formerly wintered there now travel to Louisiana's Catahoula Lake to sit out the cold months. Coastal Maine, on the other hand, is still a hotspot for sea ducks, and New Jersey's Brigantine salt marshes remain a haven for black ducks.
Of course, sea ducks require and black ducks prefer marine habitats, so that they haven't changed wintering grounds is no surprise. But what about other Atlantic Flyway ducks, especially mallards?
Ray Whittemore, DU's regional biological supervisor for the Atlantic Flyway, says that the mallard population there has increased significantly in recent years as the species has made incursions into traditional black duck breeding range in Ontario and the Maritime Provinces.
But not all of those mallards have been migrating to traditional wintering areas in the flyway over the last couple of years, primarily due to warm fall and early winter weather. Whittemore says, "Many of the mallards and Canada geese in the flyway are stacking up in the Finger Lakes of New York, particularly near Montezuma National Wildlife Refuge (NWR) and Cayuga Lake.
Row crop agriculture-corn and soybeans, especially-has continued to increase in that country, providing more food for the birds. The refuge is on the north end of Cayuga Lake, which is large and deep and stays ice-free all winter. That provides roosting water.
The cropped fields are often blown free of snow in winter, too, exposing waste grains, so you've got all the elements geese and mallards need to stay there until the weather gets too severe. When it does, they'll move farther down the flyway, but only as far as temperatures and food supplies dictate."
Habitat restoration is another reason ducks find Montezuma NWR increasingly attractive. Tom Jasikoff, the refuge manager, says, "Over the last 10 years, we've been trying to restore 50,000 acres of the historic Montezuma marsh complex. This is one of the priority projects of the North American Waterfowl Management Plan. We've been purchasing land, putting in dikes, managing water levels, engaging in some cooperative farming to provide additional food, and generally doing what we can to make the habitat favorable for ducks.
For instance, we've conducted major work to control the proliferation of purple loosestrife and cattail in an attempt to improve the ratio of emergent vegetation to water, and to return to native marsh vegetation that ducks prefer for brood-rearing habitat."
According to Jasikoff, the ducks have responded to the improved habitat, and waterfowl visitation has increased accordingly. Waterfowl hunting success has also increased, largely due to warm fall weather and larger fall flights. "Hunting is available on some parts of the federal refuge," he says, "as well as on some surrounding state lands. On the refuge portion, the number of ducks harvested per hunter visit has increased from a range of 1 to about 2.5 in previous years to 3.1 last season. Last season was a banner year."
Fall flights in the Mississippi Flyway have always frustrated duck hunters, but even more so in recent years. With vastly improved annual duck production during the last half of the 1990s and a return of 60-day duck seasons, hunters in the northern tier of Mississippi Flyway states have been particularly stymied. Duck seasons in those states start in early October, when most migrant ducks are still lingering on the Canadian prairies.
Diving ducks may or may not arrive on schedule during late October, but freeze-up often occurs in these northern states well before a 60-day season ends. By then, the majority of the fall flight of migrants, especially mallards, might still remain on the prairies or, if not, may overfly those states or only stage there for a short while, providing limited hunting opportunities.
Many of these mallards' next migratory wayside, at least in recent years, has been central Missouri. For more than a decade, Missouri has pursued a huge wetland acquisition and development program, providing migratory stopover areas for waterfowl. Some of those wetlands are moist soil management parcels that include food plantings such as corn. Given good water conditions on these wetlands and plenty of food, mallards are particularly reluctant to move farther south until cold weather mandates their eviction.
"Given a mild winter," says Tom Moorman, director of conservation planning for DU's Southern Regional Office, "mallards, in particular, adjust their strategy, for lack of a better word, to hang on at the edge of winter, near the ice line. Unlike teal, gadwall, and other dabblers, they'll stay as far north as possible. And with improved habitat available in Missouri, the birds will stay there as long as they can hold out."
Farther south in the Mississippi Flyway, weather can also wreak havoc on hunter expectations. "Dry years are especially bad for hunters on many public areas in the South that depend on precipitation to flood them," Moorman says. "This last year, for example, when it finally got cold up north, the South was dry. When that happens, and it has happened more than once in recent years, mallards overfly Arkansas and Mississippi and go all the way on to the Gulf Coast, primarily to southwest Louisiana.
Waterfowlers in Arkansas and Mississippi who own or lease property where they can pump water and manage their habitat, by contrast, will usually have very good hunting. It's interesting that waterfowl harvest figures actually tend to go up in dry years in the South, probably because the birds gravitate to areas with water, and many of these areas often are privately managed for waterfowl hunting.
"Still," Moorman relates, "given too much hunting pressure, the birds may move in large numbers to safer areas. There remains a lot we don't know about winter movements of mallards. When frozen out of some areas, the birds will move farther south, but then move back north again, below the freeze line, as soon as it becomes warmer, say during a mid-winter thaw.
They respond that way to precipitation cycles, too, flying south to the Gulf Coast without stopping at traditional wintering areas in Arkansas and Mississippi when they're dry, then flying back up to those areas as soon as they're wet, which may be only a few days or weeks later. Depending on habitat conditions, the ducks may even fly east or west to find better conditions. How the birds know how to do that-respond to habitat changes in other areas-is a mystery."