Mute Swans – Large Waterfowl
Cygnus olor Identification, Diet, Breeding, and Conservation Status
Jul 14, 2009
Mute swans, Cygnus olor, native to Europe and Asia, are familiar to most people because they are the species most commonly used in symbolism and depicted in art. They are white swans with dark legs and have an orange bill with a black knob where the bill joins the brow. Mute swans swim with their necks held in a graceful S-shaped curve, and often hold their wings in an arch over the back. Look for them in both salt and fresh water—marshes, ponds, rivers, inlets and bays.
Diet and Feeding Habits of Mute Swans
Mute Swans enjoy a mixed diet of plant and animal foods: aquatic plants, grass, grains, insects, fish, frogs, worms, and mollusks. They crop plants growing on the bottom of ponds, rivers, and lakes by reaching down with their long necks.
Though they don’t dive for food, Mute Swans can forage in quite deep water because of their long necks. In the process they stir up the bottom and often uproot plants, making food available to other animals and water birds that otherwise couldn’t get at it.
Nesting and Breeding of Mute Swans
A male swan is called a cob, a female is called a pen, and the young are cygnets. Mute Swans breed at two or three years of age. Though they’re believed to mate for life, pairs don’t always stay together indefinitely, and if one dies, the survivor may find another mate.
Mute Swans nest in wetlands or very near shallow lakes and slow moving rivers. They often build a high mounded nest over saturated ground. The nest may be located on top of a tussock of vegetation or the birds may build it from the bottom up, using dry vegetation such as grasses, reeds, sticks and rushes. The cob gathers building materials and provides them to the pen, who builds the nest.
- The pen usually lays about seven eggs, which are incubated by both adults. Eggs hatch in five to six weeks.
- Cygnets leave the nest after only one day, often accompanying the cob to the water while the pen continues to incubate other eggs and recently hatched siblings.
- Not able to fly until they are about two months old, young sometimes ride on the backs of their parents or hide under a wing. They remain with parents for four or five months.
- Young birds finally become independent when they moult and become fully white swans, or at the latest, before the next breeding season begins.
- Mute Swans can live to about nineteen years of age in the wild, though the average life span is probably less than ten years. They live considerably longer in captivity.
Do Mute Swans Migrate?
Most Mute Swans do not migrate; however, those that don’t live near people, and flocks that live in very cold areas move in winter, seeking places where the water remains open and there is food available. Young birds and nonbreeding adults undertake moult migration—migration to a different site to shed their feathers and grow new ones—away from breeding areas. During moulting, the birds cannot fly and are therefore vulnerable to predators.
Wild birds that migrate spend the winter in North Africa, India, Korea, and the Middle East.
Mute Swan Threats and Conservation
Like most birds that have adjusted well to people and to human impact on the environment, Mute Swans are doing well in most places and this is not a species of conservation concern. Significant threats to the birds include:
- Lead fishing weights or lead pellets which have been left in waterways. Lying on the bottom, these weights are picked up and swallowed by feeding birds. Remaining in the gizzard with grit that helps digest food, the lead slowly poisons the birds.
- Entanglement in discarded fishing line and other human debris.
- Water pollution.
- Overhead power lines: because swans do not see well directly in front, they frequently fail to see power lines and collide with them.
Sources
"Cygnus olor: Mute Swan." Animal Diversity Web: University of Michigan Museum of Zoology.
"Mute Swan: An Invasive Species And Its Management In Rhode Island.” Allin, Charles C. Rhode Island Fish and Wildlife. www.dem.ri.gov
“Rapid Increase in The Great Lakes Population of Mute Swans.” Petrie, Scott A. and Charles M. Francis, Bird Studies Canada www.kwic.com
“Swan.” New World Encyclopedia.
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