The adaptable Mute Swan can be found in aquatic habitats ranging from urban lakes and farm ponds to coastal estuaries. In the Pacific Northwest and from New England south to Virginia, Mute Swan pairs choose fresh, brackish, and saltwater ponds as breeding sites. Farther inland, they breed on slow-moving rivers, bogs, embayments, and creeks and streams that empty into large lakes and other bodies of water. Severe weather or food shortages may drive birds from their territories to winter with nonbreeders in ice-free stretches of lakes, rivers, estuaries, and ocean sounds.Back to top
Mute Swans mainly eat aquatic vegetation, along with some animal prey including frogs, tadpoles, fish, snails, mollusks and insects. In a Michigan study swans ate more animals during their annual molt and in spring when vegetation was scarce. Plant foods include eelgrass, several species of pondweeds, along with filamentous algae, wigeon grass, sea lettuce, bladderwort, flowering grasses, and agricultural grains. They also eat handouts from people, including cracked corn, bread, lettuce, and produce trimmings. Mute Swans are voracious foragers, eating up to 8 pounds of aquatic plants a day that they tear off with their thick, rough-edged bills anchored by strong bill muscles. They skim plants from the surface and submerge all but their tail and feet to reach vegetation growing in deeper water. They also rake the bottom with their feet to expose tubers and dig up plants to bring to the surface. Back to top
Male Mute Swans select the nest site and may start several nests before the female accepts the location. Nest sites are safe from flooding yet offer easy access to water, with ample nesting materials and food nearby - often on a small peninsula, along a heavily vegetated shoreline, or on a small to medium-sized island.
The male Mute Swan starts the nest by building a platform of crisscrossed vegetation, often on the site of a nest from a previous year. He then places vegetation next to the platform for the female, who piles the material onto the nest base, using her body and feet to mold a nest cup. Nesting materials include twigs, reeds, cattails, cordgrasses, sedges, rushes, bulrushes, other grasses, and occasionally pebbles. The cup can contain rotting vegetation and some down. The finished nest reaches 5 feet across at the base and 1.5 - 2.1 feet high, with a nest cup 15 inches across and 3 - 10 inches deep. Construction takes about 10 days, and the pair may add to the nest during egg laying and brooding.
|Clutch Size:||2-5 eggs|
|Egg Length:||3.5-4.6 in (9-11.6 cm)|
|Egg Width:||2.3-2.9 in (5.9-7.4 cm)|
|Incubation Period:||34-41 days|
|Egg Description:||Blue-green when laid, changing to white and chalky. Sometimes stained olive-brown from material on parents’ feet.|
|Condition at Hatching:||Eyes open, clumsy, covered in wet white or gray down. Able to move around nest, feed and enter water as soon as down dries. Is able to fly at 65 days after hatching.|
Short legs placed well back on the body give Mute Swans an awkward walking gait, but the birds can run quickly if pursued and can take off from land and water, flying with head and neck extended. On the water they sometimes hold their wings slightly raised and “sail” with the wind. Mute Swans are predominantly monogamous and form long-lasting breeding pairs. They are extremely aggressive in defending their breeding territory. Before or during landing at a breeding site they’ll slap the water with their feet to announce their arrival and alert potential intruders. If another swan approaches members of the pair raise their wings and tuck their neck in a “busking” display to warn them off. Territorial defenses sometimes escalate to fights between males that can end with the dominant bird pushing its rival underwater. Mute swans also chase off ducks, geese, gulls, dogs, and humans. The aggressive nature and enormous appetites of these nonnative birds pose a problem for wildlife managers: Mute Swans displace native species from breeding and foraging sites, and can damage feeding habitat by overgrazing aquatic vegetationBack to top
Mute Swan populations held steady between 1966 and 2019, according to the North American Breeding Bird Survey. Partners in Flight estimates the global breeding population at 400,000 and rates them 7 out of 20 on the Continental Concern Score, indicating a species of low conservation concern. With few natural predators, these aggressive nonnatives can increase their population quickly, displace native species, and damage aquatic habitat by overgrazing vegetation, creating a dilemma for wildlife and habitat managers. In the Maryland region of Chesapeake Bay, Mute Swans drove the last colony of Black Skimmers off their breeding grounds and trampled Least Tern nests and nestlings on the bay’s sandbars. Mute Swans are also displacing Black Tern colonies in New York. Some states have adopted measures—including addling eggs and culling birds—to control Mute Swan numbers, but these measures tend to generate public controversy. In Maryland, a population of over 4,000 had been reduced to fewer than 100 swans by 2012. Control efforts are also in place in the Central and Pacific Flyways, where wildlife managers are removing Mute Swans in efforts to reestablish Trumpeter Swan populations. Due in part to poor forward vision and maneuverability, Mute Swans are injured and killed by impacts with power lines and other structures. They are also affected by lead poisoning from spent shot and fishing weights.Back to top
Ciaranca, Michael A., Charles C. Allin and Gwilym S. Jones. (1997). Mute Swan (Cygnus olor), version 2.0. In The Birds of North America (P. G. Rodewald, editor). Cornell Lab of Ornithology, Ithaca, New York, USA.
Lutmerding, J. A. and A. S. Love. (2020). Longevity records of North American birds. Version 2020. Patuxent Wildlife Research Center, Bird Banding Laboratory 2020.
Partners in Flight. (2020). Avian Conservation Assessment Database, version 2020.
Sauer, J. R., D. K. Niven, J. E. Hines, D. J. Ziolkowski Jr., K. L. Pardieck, J. E. Fallon, and W. A. Link (2019). The North American Breeding Bird Survey, Results and Analysis 1966–2019. Version 2.07.2019. USGS Patuxent Wildlife Research Center, Laurel, MD, USA.
Sibley, D. A. (2014). The Sibley Guide to Birds, second edition. Alfred A. Knopf, New York, NY, USA.