Cygnus olor (J. F. Gmelin, 1789)

Length: 152 cm

Weight: 11800 grams

Mute swans do not mate for life, contrary to the stereotype of the 'pining swan' who has lost its mate. In fact, some have been observed to have as many as four mates, or even 'divorce' one mate in favor of another. However, established pairs are more successful breeders than non-established pairs and mute swans do mate with only one other swan during each breeding season.

Mating System: monogamous

Mute swans rarely nest in colonies. Nest sites are selected and breeding begins in March or early April. These swans either build a new nest or use a previously constructed mound, such as a muskrat house. The nest is large, made of aquatic vegetation, and lined with feathers and down. It is built well above the normal water level in swampy places near a pond or lake. It is possible for clutches of 5 to 12 to occur, but 5 to 7 is most common. The eggs are pale gray to pale blue-green. Incubation lasts 36 to 38 days. The chicks are brownish gray (gradually turning white within the next 12 months) and only remain in the nest for one day. The male may often take the first-hatched cygnet (hatchling swan) to the water while the female continues to incubate the remaining eggs. They are able to fly in about 60 days. Chicks can ride on the backs of their parents or under their wings. By the following breeding season the parents drive the young away. The cygnets then join flocks of other non-breeding swans, and during this time molt their feathers, becoming flightless for a short period of time. In the next two years, the cygnets begin to bond with a mate and begin to look for suitable breeding territory. Swans do not begin to breed until about their third year.

Breeding interval: Mute swans breed once yearly.

Breeding season: Breeding begins in March and April.

Range eggs per season: 5 to 12.

Average eggs per season: 5-7.

Range time to hatching: 36 to 38 days.

Average fledging age: 60 days.

Average time to independence: 12 months.

Average age at sexual or reproductive maturity (female): 3 years.

Average age at sexual or reproductive maturity (male): 3 years.

Key Reproductive Features: seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate)

Average eggs per season: 5.

The sexes share incubation, though the female spends the majority of time sitting, and the male usually stands guard.

Even in semi-domestication, the nest is strongly defended; swans have been known to attack other waterfowl and even people. Blows from their powerful wings can be especially painful. They can be dangerous to children, and are capable of killing or maiming some of the larger predators.

Parental Investment: precocial ; pre-fertilization (Protecting: Female); pre-hatching/birth (Protecting: Male); pre-weaning/fledging (Provisioning: Male, Female, Protecting: Male, Female); pre-independence (Provisioning: Male, Female, Protecting: Male, Female)

鉴别特征 体形和羽色与大天鹅相似。嘴赤红，前额具黑色疣突，而显然区别于其他两种天鹅。
形态 雄性成鸟(繁殖羽)：遍体雪白，头顶至枕略沾淡棕色。眼先裸露，呈黑色。
雌性成鸟：羽色与雄鸟相同，体形较小，前额的疣突不显著。
虹膜棕褐色；嘴基、嘴缘黑色，余为红色，前端近肉桂色，嘴甲褐色；跗蹠、蹼、爪均黑色。
雏鸟：头灰，略沾淡棕色；上体和两胁淡棕褐色；下体银灰色。虹膜蓝褐色；嘴石板灰色，前端常有一白点；跗蹠深灰色。
幼鸟：头、颈淡棕灰色，前额和眼先呈裸露的黑色，但不具疣突；飞羽灰白；尾淡棕灰色，尾端污白；下体较淡，呈浅棕灰色。虹膜褐色，嘴红灰色，跗蹠绿褐色。
量衡度：
性别 体重 全长 嘴峰 翅 尾 跗蹠
♂♂ (7) 9,650-10,000 1,413-1,550 80-86 600-620 190-215 95-110
♀♀ (2) 8, 600-8,750 1,412-1,493 74-76 560-570 190-192 90-94

Mute swans are large and aggressive birds. As adults they are not often preyed on unless they are old or ill. Eggs and hatchlings are vulnerable to nest predation by raccoons, mink, and a wide variety of other medium to large-sized predators. But swan parents are typically present to protect their young.

Known Predators:

• raccoons (Procyon lotor)
• American minks (Neovison vison)