On either side of Halloween, and continuing all through November, as chilly winds blow from the north to shake leaves from trees, many small chunky black-and-white ducks mysteriously show up along the Jersey Shore. Out of nowhere I spot these buoyant little diving birds in sheltered back-bays and estuaries along the coast, and even in far-off lakes and reservoirs inland.
Buffleheads (Bucephala albeola) have returned to spend another winter in New Jersey. Look carefully, they are not always easy to find. Buffleheads are the smallest diving or sea ducks in North America. Buffleheads only weigh about one pound and are about 15 inches in length, comparable in size to a crow.
PHOTO: Buffleheads (Bucephala albeola)
But despite their petite proportions, buffleheads are constantly in motion, especially in or around water. They are either flying straight up from the water, swimming on the water’s surface or diving underneath the water in search of food. Buffleheads are expert divers, they use their feet for propulsion while holding their wings close against their bodies, similar in how many other sea ducks like loons and mergansers forage for food in water. Buffleheads are able to remain underwater for more than a minute or so to forage for food.
Buffleheads have adapted to live in both freshwater and saltwater environments, and to have a highly varied diet for any duck. They can dive for both insect larvae, seeds, and amphipods in freshwater ponds and lakes, and for crustaceans, mollusks, and small fish in coastal areas.
It’s no surprise then with all this motion that buffleheads have an active metabolism, they need to feed almost constantly. While swimming, the birds are always rapidly disappearing underwater, and popping back up, spending nearly half their time underwater to search for food.
Buffleheads are gregarious among themselves and will scamper about in the water amid a flock of five, ten, or more. But these birds are wary of trouble. Whenever I observe a flock of buffleheads, there is always one, usually a male, that acts as a sentry to warm others of danger. When trouble comes within 50 feet of the flock, the buffleheads swiftly spring forward from the water’s surface and with rapid wingbeats take to the air. It makes for some exciting bird watching.
But for all their speed, it’s not an easy journey for these little ducks to migrate to the Jersey Shore, let alone arrive nearly at the same time every year. In preparation for their fall migration, many will become avid feeders, to eat and eat and eat, so much so that these birds will gain about 25 percent in body weight. With full bellies, the ducks fly thousands of miles over mountains and meadows in small flocks from boreal forests in northern Canada and central Alaska where they breed. Like most small birds, buffleheads migrate at night to avoid predators, including hawks, falcons and bald eagles. Air temperatures are also usually cooler at night, which can make this daunting high-energy activity a bit more tolerable.
These water loving birds often follow river systems and other aquatic habitats to return to the same wintering area year after year for generations. Their winter distribution is generally split into two populations, one on the east coast and the other on the west coast of North America. On the east coast the highest accumulation of buffleheads is generally found from New Jersey southward to Virginia and North Carolina.
So why migrate at all if it’s so strenuous? Cold temperatures don’t really concern these birds. Buffleheads have thick layers of fat and downy feathers to insulate them. So much natural fluff and fat that the birds seemingly appear to relish cold weather.
It’s the need for open water that is essential for their survival. Ducks need water to survive and require open water to forage and feed. This is certainly true for buffleheads. They migrate from northern forests before lakes, ponds and river systems freeze up. This is why many buffleheads head to the coast during the winter. Since saltwater freezes at a lower temperature than freshwater because of the salt content, at about 28.4 degrees Fahrenheit, estuaries, bays and ocean waters in New Jersey remain largely ice-free during the winter, except during extremely cold winters. These coastal ecosystems play an important role in the survival of buffleheads during long, cold conditions.
PHOTO: Buffleheads (Bucephala albeola)
To the average person, they look like no ordinary duck. The name bufflehead comes from a combination of two words: buffalo and head. It refers to the puffy bulbous head shape of the duck, like a buffalo. Males have a very bulbous head for such a small butterball body. The head shape is most noticeable when a male puffs out its feathers, the head resembles a wild looking black-and-white bonnet or a large cap with a short wide beak.
Buffleheads surely do not look like mallards, the most common and easily recognizable wild duck in the Northern Hemisphere. No, these ducks are often shy and more secretive. In fact, buffleheads don’t even like to flock together with other species of ducks, including mallards. But while buffleheads are less sociable than most other ducks, their cuteness makes up for their coyness.
Take a close look with binoculars and you will be greeted with a kaleidoscope of colors, especially on a sunny day. The black on the back of the male’s head is overlaid with iridescent purple, blue, and green, and even more colors depending on the brightness or location of the sun. The glowing effect is really quite amazing, and the variety of colors can be absolutely stunning, like an iridescent rainbow.
Female buffleheads, on the other hand, like most ladies in bird world, are dull and drab in color. They have a large rounded head but lack the lively black-and-white feathers. Female buffleheads are more grayish brown in color with a white patch on their wings and a small white smear of feathers on their cheeks. Enough color to take notice, but not to be charmed.
Why are male birds frequently more colorful than female birds? No one is quite sure, but there are many good ideas on the issue. In 2005, Scientific American magazine published an article by Robert Heinsohn, a professor of evolutionary biology at the Australian National University. He suggested that Charles Darwin more than a hundred years ago had the best answer. Heinsohn writes:
“Darwin concluded that color differences between sexes in birds (also known as sexual dichromatism) result largely from female preference for bright colors in males. This general rule has received much support since Darwin's time, but other influences have also been noted. For example, females of species that are exposed to predators while incubating tend to have dull colors, although both sexes may be brightly colored in species that nest in tree hollows because the females are less visible to predators. Color can also aid individuals in recognizing members of their own species. And in species that are not good to eat, [dull] colors can provide a warning to potential predators.”
Sexual difference in color seems to suit the buffleheads well. The species has been around for at least a half-a-million years. Fossils from the late Pleistocene (about 500,000 years ago) found in Alaska, California, Florida and other states show that this duck has been in existence for a very long time. In fact, one California fossil that resembled a modern bufflehead even dated back to the late Pliocene, two million years ago.
Perhaps one reason for this longevity is that unlike most ducks and waterfowl, buffleheads are monogamous (though 90% of bird species overall are monogamous). About 56 percent of waterfowl species do not form long-term pair bonds. Instead, males must form new bonds each year by finding a new mate, participating in courtship displays and competing with other males for the attention of a female. But not buffleheads, they remain with the same mate every year to devote all their energy to help raising young and ensuring nesting activities are successful.
And it’s their nesting activities that might play even a bigger role in their survival. Unlike other waterfowl, buffleheads do not nest on the ground. They have evolved with their small size to fit nicely in a nesting cavity of a woodpecker, preferring holes excavated by Northern flickers or sometimes Pileated woodpeckers.
That’s right, buffleheads are small enough to raise a family in tree holes left over from woodpeckers. It’s an amazing adaptation for a sea duck. I think only goldeneyes, a cousin of the buffleheads and another beautiful looking diving duck, similarly nest within tree cavities in northern forests.
The hollowed-out nesting cavities that buffleheads favor are usually within 50 feet (15 meters) of a body of water, such as wooded lakes and rivers, but avoiding dense wetlands and muddy waters. Nests are often found in poplars and aspen trees, and occasionally pine trees. Nests are usually 10 feet (3 m) above ground, though sometimes up to 50 feet (15.2 m) high. Usually, 8 to 10 cream to pale buff eggs are laid inside each nesting cavity.
It’s not an easy process for buffleheads to raise a family. Females usually scout out their nest location up to a year in advance. If the desired nest is occupied by another bird or animal when she returns, she has to start all over again and search for another abandoned woodpecker hole with the male. With so many trees, you would think the search would be simple, but it’s not. The birds need to find the perfect nest. The Cornell Lab of Ornithology states that the average nest entrance for buffleheads is approximately 2.5 inches (7 cm) in diameter. “Larger entrances are normally avoided because they are favored by goldeneyes, which can kill buffleheads in larger nests, but cannot enter the smaller entrances where buffleheads nest.”
PHOTO: Buffleheads (Bucephala albeola)
This is not the only threat that both hatchlings and adults face. Breeding so far north, cold weather can cause mortality. On November 4, 1940, in east-central Saskatchewan, Canada, many buffleheads died as they were beginning their fall migration southward. No one is quite sure what happened, even over seventy years later, but Kerry Finley, a wildlife biologist from Luseland, Saskatchewan, believes these unfortunate birds encountered a heavy dense fog system coming off a nearby lake, while almost at the same time very cold winds were blowing down from the Arctic. These two conditions combined to overwhelm the little wet birds and to hurtle thousands to the ground from the night sky.
Unfortunately, buffleheads have a wide array of threats that possibly impact their present and future survival rate. One of the biggest hazards is climate change. The National Audubon Society tells us that buffleheads are highly vulnerable to climate change, with up to 68 percent of their boreal forest breeding habitat in Alaska and Canada shifting farther north and becoming greatly reduced in size. The Yale School of Forestry and Science concurs that “boreal forests are expected to be especially sensitive and vulnerable to climate change because those ecosystems are naturally sensitive to warming, because of the nature of their soils (peat and permafrost are prevalent) and the likelihood of increased incidence and extent of wildfires.” A study published in 2018 by the University of Alberta goes even further to suggest that “half of Alberta's upland boreal forest is likely to disappear over the next century due to climate change…the upland forest will be replaced after wildfires by open woodland or grassland, according to research from biologists.”
Another major threat to buffleheads is the loss of habitat due to poorly planned development. The boreal forest has been hit hard over the past few decades by logging, mining, oil and gas extraction, and hydroelectric development. While the southern boreal forest in Canada remains the area most affected, development continues to slowly move further north into the heart of the boreal forest each year. More than 30% of the Canadian Boreal Forest is slated for some form of industrial development in the next several years. In southern areas, the forest is being lost at a rate of one percent per year—a pace as rapid as the destruction of the tropical rainforests. Without conserving large portions of the boreal forest, there will likely be long-term declines among numerous boreal bird species including buffleheads.
The good news is that presently the global population of buffleheads seems to be stable and even slightly increasing. According to assessment information completed in 2016 by the International Union for Conservation of Nature and Natural Resources, “the population trend appears to be increasing, and hence the species does not approach the thresholds for Vulnerable under the population trend criterion (>30% decline over ten years or three generations).”
But in a world where many species of birds are in decline, we need to take this news with caution. On average, buffleheads live only 2.5 years in the wild. So, it wouldn’t take much disturbance to cause the population to become threatened rather quickly.
With a global population estimated to be more than a 1.2 million birds, according to data released in 2006, the buffleheads seem healthy, but are in fact under pressure from climate change and habitat loss. Would we even know if these birds were slowly in decline? A 50 percent drop in population within 25 years would need on average no more than a 2 percent reduction each year. A mere drop in the bucket and largely unnoticeable to most people.
Every time I take a beach walk, I am frequently reminded of just how complex the lives of many coastal and sea birds are, from migration to breeding to feeding. If buffleheads are to remain healthy and happy, humans must be good stewards and ensure that the ecosystems these birds rely on for their survival in the boreal forests in Canada and Alaska to estuarine waters along the Jersey Shore remain protected, healthy and dynamic.
To see more pictures, videos and ways to save wildlife along the Jersey Shore, please visit the website: www.savecoastalwildlife.org.