I received an early and unexpected Christmas present last weekend when the birds were flying and decoying well. My hunting partner kicked the morning off with a high overhead shot on a greenhead, then I folded a pair of eiders neatly over the decoys. After fetching all three birds, Matt returned to the blind an announced that the mallard and one of the eiders sported bands, or what we wildfowlers refer to as jewelry.

While waiting for more birds I pondered the rarity of such an occurrence. The mixed bag itself was unusual. Eiders are sea ducks that typically spend their lives on the islands, coastal ledges and open ocean environs we were hunting. Mallards, on the other hand, are puddle ducks, found most commonly in inland freshwater marshes and ponds. But late in the season when the inland waters freeze, they occasionally head for the coast. The differences don’t end there.

Intuitively, when one thinks of waterfowl migrations, the typical travel route involves a sojourn from high Arctic nesting grounds to southern wintering waters. Dabblers or puddle ducks like the mallard nest predominantly in the prairie pothole region of west-central Canada, though there are smaller populations in the east, like the one in Pierreville, Quebec, that produced Matt’s mallard. Eiders nest much more locally, along the coast of Maine and the Maritime Provinces as well as in the Gulf of St. Lawrence and St. Lawrence estuary, where my eider was banded.

As with any such adaptation, there are costs and benefits. The principle benefit of nesting so far south is the birds needn’t travel far between seasons. While Canadian birds do congregate along our coast, many of the birds that winter here are locals that may not travel more than a few hundred miles from their nesting grounds.

One cost of that strategy is increased vulnerability to humans. According to the Joint Working Group on the Management of the Common Eider, which includes the Canadian Wildlife Service and Ducks Unlimited Canada, among others, “Recreational tourism activities such as sea kayaking, the development of tourism projects and residential use (cottage developments) constitute real threats.” The biggest threat from a human standpoint is disturbance in colonies during the nesting period, which can result in nest desertion.

Eiders are also extremely susceptible to predation, the worst source being gulls that cohabit nesting islands. Mammalian predators take their share of eggs, young eiders and adults, too, and often tend to be more abundant in areas of human habitation.

Mallards and other puddle ducks nesting on the prairie potholes face a more indirect human threat. Over the last two centuries much of the arable land has been converted to agriculture. Even where wetland pockets are preserved, a sometimes distinct and isolated nature make them highly attractive to predators.

The two species also have very different life cycles. Eiders don’t breed until they are three or four years old. They have relatively small clutches of 3 to 5 eggs and it’s estimated that fewer than 10 percent of ducklings will survive to fledge. But they are long-lived, and may nest and produce young for up to 15 years. Mallards don’t live nearly so long, but they begin nesting at age 1 and produce clutches of 8 to 13 eggs. Over the last two to three decades the latter strategy seems to be the more successful one; mallard numbers continued to rise while eiders have been on a slow decline. At least that was the case.

Federal and state wildlife agencies monitor these trends, and adjust season lengths and bag limits accordingly to ensure the resource is not over-exploited. The eider bag limit has been reduced several times and more recently the season was shortened by six weeks. Meanwhile, mallard bag limits have remained stable or increased as the population waxed and waned, (mostly waxed) depending largely on spring nesting conditions. But that’s about to change.

The mallard population that breeds in the Northeast and migrates principally in the Atlantic flyway is considered distinct from the larger prairie pothole population that migrates along the Mississippi, central and Pacific flyways. It also has declined by about 20 percent since 1998. It’s cause for concern but not alarm, and hunters will see a reduction in the bag limit next year. Ironically, not so long ago biologists were questioning whether mallards even belonged in the East, fearing they were diluting the genetic strain of native black ducks. But that’s another story for another day.

Bob Humphrey is a freelance writer, registered Maine guide and certified wildlife biologist who lives in Pownal. He can be reached at:

bhhunt@maine.rr.com