Mute Swans, known for their grace and elegance, undergo a fascinating life cycle filled with dedicated parenting, essential survival behaviors, and the eventual transition to independence. From the formation of lifelong pair bonds to the challenges of raising young and the crucial process of molting, understanding these aspects offers a deep appreciation for these magnificent birds. This guide delves into the intricate details of a Mute Swan’s existence, providing insights for those interested in avian life and the natural world.
Mating and Breeding Rituals
Following their departure from their parents at six to ten months of age, juvenile Mute Swans often form social flocks until they reach sexual maturity between two and three years old. Once mature, they select a lifelong mate. As the breeding season commences in March and April, the male, known as the cob, and the female, the pen, dedicate approximately three weeks to constructing a nest. Their choice of location prioritizes safety from predators and flooding while remaining close enough to water for newly hatched cygnets to access easily.
The swans’ courtship is a beautiful display involving calls, greetings, synchronized neck movements, and rhythmic head-dunking. The mating act itself involves the cob positioning himself on the pen’s back, using his beak to gently hold her neck to prevent her head from submerging. The ritual concludes with the pair rising from the water, chests touching, emitting a purring sound.
The Incubation and Hatching Process
During the breeding season, the pen lays one egg every one to two days, completing a clutch of five to nine eggs. Incubation does not begin until the entire clutch is laid. Throughout this period, the pen remains on the nest almost continuously, rarely leaving. She develops a specialized brood patch on her abdomen—an area where the skin, devoid of feathers, comes into direct contact with the eggs, providing essential warmth. To ensure even development, she regularly rotates the eggs with her beak. This meticulous process ensures that Mute Swan eggs hatch concurrently, despite being laid over several days.
The pen’s dedication to incubation, often foregoing even meals, leaves her weakened and vulnerable. To protect her and the eggs, the cob sleeps on land nearby each night. His other vital role is actively patrolling their territory to deter other swans, who could pose a threat to his family and offspring.
Approximately 35 days after incubation begins, typically in May, all the eggs hatch within a 24-hour period. The cygnets utilize a small protrusion on their bills, known as an “egg tooth,” to score and crack the eggshells, enabling their emergence. This hatching process can take several hours and is an exhausting feat for the young. Newly hatched cygnets are wet and grey, but quickly dry to a fluffy appearance, with black bills. They spend their initial hours nestled under their mother’s wings, resting and beginning to explore their surroundings. A few days post-hatching, the family abandons the nest, leaving any unhatched eggs behind.
Pair Bonds and Parental Dedication
Mute Swans exhibit profound loyalty, forming lifelong pair bonds and demonstrating dedicated co-parenting. Within 48 hours of hatching, both parents guide their cygnets into the water for their first swim. Initially, parents help pull up underwater plants for the cygnets to eat before teaching them to forage independently. As the cygnets grow, parents demonstrate how to “dabble”—upending themselves to reach food—and the essential skill of preening, which involves bathing, cleaning feathers, and distributing oil from a tail gland. Once their feathers develop, parents also teach them to fly.
Parent swans diligently teach their young to recognize and evade dangers. Upon perceiving a threat, they issue a danger call and swiftly guide the cygnets to safety, often adopting defensive postures with wings spread wide and hissing. As cygnets mature, parents impart further defense strategies. The cob primarily defends the territory, patrolling and chasing intruders by “bussing”—puffing up his body and advancing rapidly—until they retreat. The pen will also defend if necessary. Cygnets begin to practice these skills around four to five months old but often rely on their father’s protection in confrontations. If one parent perishes, the surviving parent assumes full responsibility for raising the young. Swans who lose a mate typically seek a new one.
Diet and Nutritional Needs
The primary diet of Mute Swans consists of submerged aquatic vegetation, accessed by upending and extending their long necks underwater. Parents actively assist their cygnets by pulling up plants or churning up water to expose vegetation and insects until the young can fend for themselves. Swans drink as they eat, and feeding them on shore, particularly with human food, is perilous as they can choke without water. Processed foods like bread can lead to a condition known as “angel wing” in cygnets, causing abnormal wing bone development and rendering them vulnerable to predators.
The Moulting Process
Annually in late summer, Mute Swans undergo molting, a process where they shed old feathers and grow new ones. This typically takes about six weeks, during which their flight feathers are lost, rendering them flightless. This timing is strategic, occurring after the energy demands of nesting season. While they may need to fly considerable distances in winter if their territory freezes, winter is still months away. If a mated pair has cygnets, they molt sequentially rather than simultaneously, ensuring one parent can always fly. Usually, the pen molts first. During this period, their wings appear shortened and wispy, with loose feathers, followed by the emergence of new feather shoots.
Learning to Fly
Autumn marks the season when young swans, or cygnets, learn to fly. With fully grown feathers, they prepare by stretching their wings and flapping to build necessary flight muscles. The parents, having completed their molts and regained flight capability, guide these lessons. They typically gather the cygnets in a designated water area, with one parent leading and the other at the rear, facing the wind. Due to their size, Mute Swans require a substantial stretch of water for takeoff, initially appearing to run across the surface before achieving lift-off and tucking their legs behind them. While most cygnets follow their parents, some struggle initially, requiring practice to gain altitude and improve landing accuracy. Their flights gradually lengthen as their endurance builds.
Swans possess strong chest muscles and lightweight bones, including many hollow ones, facilitating flight. Their efficient respiratory system allows them to breathe up to ten times faster during flight than mammals, ensuring adequate oxygen supply. While capable of flying at thousands of feet on long journeys, they typically fly lower for shorter distances, usually not exceeding 400 to 500 feet. Flight is a crucial defense mechanism, but for inexperienced young swans, it carries risks. Swans’ eyes are positioned on the sides of their heads, aiding in predator detection but limiting forward vision, making them susceptible to collisions with obstacles like wires and poles. They can also misjudge geographical features, mistaking snow-covered roads for open water in winter. Cygnet mortality is highest in the first two weeks of life due to vulnerability, but fledging—leaving their parents—represents the second riskiest period. Parental insistence, particularly from the cob, ensures that cygnets eventually leave to establish their own lives.
Mortality Factors and Lifespan
Mute Swan eggs are highly vulnerable to a range of predators, including herons, raccoons, foxes, minks, and coyotes. If eggs hatch, approximately 50% of Mute Swans survive to one year of age, with most mortality occurring within the first two weeks due to cold, storms, and predation. Older juveniles and adults face threats from boats, cars, fishing gear, fireworks, hydro lines, and human structures. Predators such as coyotes, wolves, foxes, off-leash dogs, snapping turtles, rats, gulls, and raccoons frequently injure or kill swans. Disease and severe weather also contribute to mortality. Notably, many Mute Swans in Ontario perished from starvation during the harsh winters of 2014 and 2015 and from flooding in 2017. The average life expectancy for Mute Swans in the wild is 11 years.
