Birder’s Notebook: Tundra Swan
What a marvelous sight it is each fall to see hundreds of tundra swans, tipped up, feeding voraciously in the waters of Bonanza Channel and Safety Sound.
On recent drives along Safety Sound, the elegant white birds stood out amidst a rich mix of ducks, geese and cranes. A migratory symphony was playing and the musical murmuring of swans filled the air, carrying for miles. This is not just a feast for the eyes and ears, but also an important subsistence resource for people throughout the region.
Tundra swans, or whistling swans as they were formerly called, are the most abundant swan species in North America. They breed across the north in tundra regions of coastal Alaska, northern Canada and northern Russia.
In North America, eastern and western populations are designated by where they winter. Our swans are part of the western population that follows the Pacific flyway along the east side of the Rockies, through Utah and Nevada to central California.
Our region supports a healthy and widespread breeding population of tundra swans. Pairs arrive in the spring as early as conditions allow, usually from late April to mid-May, flying directly to their breeding territories, which are spread out over the landscape. Their arrival is often little noticed. Following the breeding pairs, young nonbreeding birds arrive to feed and mature over the summer months. In June, they can be seen congregating in large numbers in bays, lagoons and estuaries to feed.
Because the rearing period for young swans is long, pairs must begin nesting as early as possible, often returning to their established territories when the land is still frozen.
Our region offers many suitable breeding sites scattered widely across wetlands near large lakes, which provide submerged vegetation for food and an escape from danger.
Territories are up to half an acre in size and pairs defend their area of water and tundra from other swans, geese and long-tailed ducks. Usually this is accomplished by chases and displays, but serious fights resulting in injuries do occur.
Tundra swans are monogamous for life or until one of the pair dies. They form pair bonds when they are two- or three-years-old and first breed a year or two later. Young pairs establish a territory at least a year before they breed and pairs stay on their territories even after nesting failures.
Swans select an elevated mound for their nest, with good visibility, usually near the shoreline of a lake. The pair spends four to nine days building the nest out of vegetation that they pull in with ritualized movements from the immediate area around the nest mound, often refurbishing old nests.
They are very expressive birds, maintaining their pair bond throughout the year with ritualized displays of head bobbing, wing quivering, and neck and body extensions. Ritualized bathing and head dipping are added to their repertoire before mating.
Three to five eggs are typically laid between mid-May and mid-June. Both birds incubate, but the female spends more time on the nest while the male defends their territory.
Clutches begin hatching in midJuly after about a month of incubation. At hatch, the young, called cygnets, have open eyes and are covered with down. They are quickly mobile and within a few days the cygnets follow their parents onto the water to feed.
In the breeding season, tundra swans eat mostly aquatic vegetation that they dabble for or grab while tipped up with their long necks reaching down up to three feet to find leaves, stems and roots of submerged plants.
At first cygnets are too buoyant to tip up or even swim with their head and neck submerged. The parents uproot vegetation with their feet while the young dabble along behind, hoovering up plant material as it rises to the surface.
Swan families also graze on vegetation in tundra meadows, eating stems, leaves, fleshy roots, seeds and berries. While mostly vegetarians, they do eat some aquatic invertebrates and insect larvae.
Swans are very wary and watchful. Parents can easily defend their eggs and young from predators such foxes, gulls, jaegers, ravens and weasels, but leave the nest or swim away from larger threats such as people or bears in order to take attention away from the nest. It is remarkable how easily the big white birds can disappear into the surrounding vegetation!
Young swans are able to fly in about 45 days. The adults molt in July and are flightless for about a month. In September, when the entire family can fly, they join large, gregarious flocks of nonbreeding swans at staging areas such as Safety Sound.
Nonbreeders also molt in July while dispersed across the wetlands and lower river deltas throughout our region. They return to staging areas in late August before the arrival of family groups. By early October most swans are gone from our region, taking off with a galloping of wings against the water.
Tundra swan families stay together throughout the winter and spring migration. The young finally separate from their parents when adult pairs return to their breeding territories.
Breeding success varies from year to year. Harsh spring conditions can result in fewer and smaller clutches. When nesting is late, the young may not be able to fledge before freezeup, especially if ice forms early.
Water shortages in wintering and migratory stopover areas are an increasing concern, but tundra swans are doing well in our region and elsewhere.
Their numbers increased significantly since the 1960s when around 500 swans were estimated on the Seward Peninsula. More recent estimates often exceed 7,000 swans – plenty of swans to support a spring subsistence harvest of birds and eggs and a fall permit hunt.
For now, swans are a bright spot in the bird world. Whether they bring you delight or food for the table, enjoy the spectacle if you can as they fatten up by the hundreds for their annual fall flight to California.