Why, when so many waterfowl populations are shrinking, is this little tuxedo duck thriving?

ON A FROSTY SATURDAY afternoon in December, a week before Christmas, when the stores and sidewalks of Toronto teem with shoppers, the Leslie Street Spit is deserted. With the temperature at -5 C, only a few hardy hikers, bikers and runners are braving this windswept, five-kilometre-long finger of landfill, which arcs out into Lake Ontario just east of the Don River.

Image above: Because of their high metabolic rate and small size, buffleheads feed almost nonstop day and night during winter

Check that: Although the frozen paths are empty, the boat slips and lagoons surrounding the spit are full of waterbirds, such as gulls, geese and hundreds of ducks — small clutches of mallards that dabble by the shore, and modest pods of migrating or wintering black-and-white sea ducks that paddle away at the slightest disturbance. Among the latter are long-tailed ducks, scaup, common goldeneyes and — the object of today’s quest — buffleheads. At first glance, all these so-called tuxedo ducks aren’t easy to tell apart. But with a little time and close observation, the distinctive tails, eyes and heads of each species start to reveal their various identities.

Unless you’re a birder, you are probably unfamiliar with these birds. They appear on the Great Lakes and other large southern Ontario waterways only in late fall, winter and early spring, when relatively few people are around to see them. And among these species, buffleheads are the smallest and least plentiful. Most of the estimated 1.4-million North American buffleheads winter off the Atlantic or Pacific coast. On the lower Great Lakes, even at peak time, they only number in the hundreds at individual locations or in the low thousands across the region. In summer, buffleheads return to the boreal forest in the north and west to breed, nesting in abandoned holes that northern flickers and other woodpeckers excavate.

Male buffleheads are especially striking, with tell-tale blocky white patches around their napes, black backs, and iridescent dark green, purple or black foreheads. Females have more muted colouring, with fewer white markings on their grey-brown bodies. Buffleheads’ small size further sets them apart — they are North America’s smallest sea duck, ranging in weight from 325 to 450 grams. They feed constantly and tend to congregate in small groups rather than large pods, or “rafts,” like other sea ducks. “They are easy to find, but skittish,” says birder and naturalist Mark Cranford, a member of Ontario Nature’s Board of Directors. “If you’re a photographer, you have to move fast. They dive a lot.”

While popular among birders for their looks and active behaviour, buffleheads are one of the least-studied and most “under-respected” sea ducks, according to Michael Schummer, a scientist with Long Point Waterfowl in Port Rowan. “They tend to fall between the cracks,” he says. “They’re not really economically important and their numbers are doing well. Yet we don’t really have a handle on what drives the bufflehead population like we understand other populations of ducks.”

Schummer first studied the bufflehead while working on his PhD at the University of Western Ontario almost 10 years ago. What drew his attention then was the fact that Lake Ontario bufflehead numbers — as well as those of long-tailed ducks and common goldeneyes — had surged through the 1990s. “Right after zebra mussels were introduced, diving duck numbers went up [to] almost 10 times as many as there used to be on Lake Ontario,” says Schummer, citing the results of the Toronto Ornithological Club’s annual waterfowl counts along the north shore. “We wondered: Is there enough food to sustain them?”

Male buffleheads are especially striking — easy to find for winter birders, but “skittish”

The answer, after two winters of intensive research around Prince Edward County, turned out to be yes. While the buffleheads in his studies didn’t actually eat either zebra or quagga mussels, they did feed on much smaller chironomid (midge) larvae and amphipods (freshwater shrimp) that live among the mussels. “There’s more food than they could eat,” says Schummer.

When so many stories in the conservation arena are about habitat loss and species decline, the bufflehead’s success seems worthy of greater study. This is especially true given that some other duck species, such as scaup, that also nest in the boreal forest and winter alongside the bufflehead have plummeted in number in recent years. Understanding how and why the bufflehead is thriving could help scientists determine how to reverse the decline of other species. Researchers like Schummer are making the case that it is time to give the bufflehead some respect.

Rafts of sea ducks gather on Lake Ontario around the Leslie Street Spit in late fall and winter

BACK AT THE SPIT, a pair of buffleheads tip their heads to the water, roll forward and dive into the cold blackness in search of food. Most of their feeding happens close to shore, as this species can dive to a depth of only three metres. The pattern repeats. And repeats again.

Because of their small size and high metabolic rate, buffleheads practically feed nonstop, day and night, in the heart of winter. And even then, says Schummer, they get skinny toward late February and March. “They’re in a negative energy balance basically the whole winter long,” he explains.

While their situation sounds harrowing, buffleheads seem to be managing just fine. Overhunting cut their numbers severely in the early part of the 20th century, but the species has been rebounding ever since, due to protection under the Migratory Birds Convention Act and other conservation measures. On their Ontario wintering grounds, a number of relatively mild winters have also helped the species.

But the biggest reason for the buffleheads’ resilience may be the continued availability of ample habitat for breeding in the boreal and aspen parkland forests. Compared to southern forests that were cleared for agriculture, more of the boreal forest is still intact, and, as cavity nesters, the birds have benefitted from policy-makers’ and loggers’ increasing awareness of the important role dead, dying or sick trees (or snags) play in the boreal ecosystem. These trees help woodpeckers thrive, and they, in turn, leave their empty holes for buffleheads to use as nests.

The ideal bufflehead nest site is a flicker hole six or seven centimetres in diameter and lined with downy feathers. According to the Ontario Breeding Bird Atlas, comprehensive studies of bufflehead breeding sites are tricky because only a small number of the birds inhabit any given area, and those locations are usually remote, often accessible only by canoe. But researchers generally find buffleheads’ nests within 25 metres of ponds or small lakes.

Unlike many ducks that have multiple breeding partners, buffleheads tend to keep their mates for several years, and often return to the same nest sites year after year. There, females lay four to 17 eggs, one every two to three days. Incubation lasts about a month. Female buffleheads are strong defenders of their territory but abandon their brood at a mere five or six weeks of age; their offspring do not fledge for another three to four weeks. Until they can fly, the youngsters often gather in larger brood flocks.

The biggest concentrations of breeding buffleheads are found in British Columbia and along the Athabasca River in northern Alberta. According to the Sea Duck Joint Venture, a research partnership between the Canadian Wildlife Service, the U.S. Fish and Wildlife Service and other governmental and non-governmental groups, buffleheads that breed west of the Rockies winter on the Pacific, while the birds that breed in the Northwest Territories and east of Alberta migrate southeast over the Midwest and Great Lakes to winter on the Atlantic coast and the Gulf of Mexico. Buffleheads from Alberta migrate to both coasts.

In Canada, the largest populations of wintering buffleheads show up in south-coastal British Columbia, and the bird has a much higher profile in that province. In fact, the town of Sidney on Vancouver Island has a pair of buffleheads on its coat of arms, and every October 15 marks All Buffleheads Day — the date of the bufflehead’s return to Sidney harbour. In Ontario, annual Christmas bird counts are about the only times when this species gets any attention at all.

STILL, THE DUCK DOES have its fans. Ted Cheskey is the manager of bird conservation programs at Nature Canada, based in Ottawa. Asked what comes to mind when someone mentions the bufflehead, he answers, laughing, “Winter. Open water. Cold.” But he’s a birder, and he quickly adds, “It’s a species I certainly like a lot. Their interactions are always interesting.”

In the Ottawa area, Cheskey sees migrating buffleheads around the Little Chaudière Rapids and other open stretches of the Ottawa River. Earlier in his career, he worked on the Grand River in southwestern Ontario and would come across the ducks occasionally on Christmas bird counts. He noticed that the buffleheads seemed to associate with the relatively rare harlequin duck. “I’m not sure if it’s a coincidence or if it’s more than that. [The two species] are close in size and the females don’t look that different.”

Sidney, B.C.’s coat of arms features a pair of buffleheads

Birder Mark Cranford, who is the compiler of the bird counts for the South Peel Naturalists’ Club, says that during a typical Christmas count, his club would count around 300 bufflehead in its survey area, which includes much of the Lake Ontario shoreline around Oakville and Mississauga. But the most comprehensive data on bufflehead populations come from Schummer. Every January since 2002, he has tabulated the numbers of the 35 species of waterfowl found along the lower Great Lakes, from the Quebec border to Lake St. Clair, using both U.S. and Canadian surveys. The 10-year average for the bufflehead is around 7,000, with a one-year high of about 13,000 and a low of 2,400. Those figures compare to an average of 19,000 common goldeneyes and more than 57,000 long-tailed ducks. Temperatures and the extent of ice formation play big roles in bufflehead’s year-to-year variability, since the birds can’t feed in deep water. “When you get a lot of that shore ice, they are — how would you put it? — screwed,” says Schummer.

The bufflehead can be difficult to track because it tends instead to travel and dive in small groups and pairs. The most Schummer has ever seen together out on Lake Ontario in winter is maybe 300 birds. “With long-tailed ducks, you might see a pod or a raft of 5,000,” he says.

Before joining Long Point Waterfowl in southwestern Ontario, Schummer, an American, worked as a waterfowl biologist for the state of Maine, and he says the buffleheads he saw in the Atlantic Ocean behaved the same way. “We flew surveys along the coast there and I never saw them in really large bunches. When you get down to Chesapeake Bay, they start to form slightly larger flocks. But a common group, even in the ocean, is anywhere from four to 10.”

For some time, Schummer has been making the case that the bufflehead deserves more focused scientific attention. At the 2011 Sea Duck Joint Venture conference in Alaska, a graduate student with Long Point Waterfowl presented a paper outlining the important role the lower Great Lakes play as freshwater resources for sea ducks staging and wintering in eastern North America. In that report, the growing abundance of long-tailed ducks, buffleheads, goldeneyes and scoters was noted. But Schummer stresses that research is increasingly important as more duck-feeding habitat and sites along migration routes are being considered for industrial wind turbines. There is also concern that buffleheads and other birds may lose breeding habitat in the northern forests due to overcutting, disease or poor forest management.

However, at a time when budgets are tight, organizations like the Sea Duck Joint Venture are selective about their research. The group has not funded any studies on the bufflehead, focusing instead on threatened and endangered species, such as the harlequin duck and certain eiders. “I asked the question [at the conference]: ‘If not now, when?’” says Schummer. He worries that if bufflehead populations were to suddenly decline, a lack of data and understanding could hamper efforts to respond. “Unless something’s really staring us in the face, we might not really know why.”

In an ideal world, Schummer’s arguments make sense. But, unlike many birds whose worlds have been turned upside down by habitat loss and migratory burdens, at least the bufflehead, with plentiful food and vast stretches of habitat, has time.

This article was originally publish in the Spring 2012 edition of ON Nature magazine. Photos courtesy of Kerry Banks (top two images); other is my own