For many people, swans are the birds that people picture when they think of love. Images of swans with their necks twined around each other or in the shape of a heart abound in popular culture. But do these elegant white birds deserve their doting reputation?
In a word: yes! Swans form monogamous pairs that can last for years. Sort of.
Not all swans will mate for life, however. Think of it in the same way you think of human relationships. Some people stick together for decades, a lifetime, or for just a short time because they aren’t compatible. They’ll also regularly cheat on their mates.
There are some interesting details about the mating habits of swans, so let’s fly right in:
Do All Species of Swans Mate for Life?
All species of swans are monogamous, but not all of the birds will stay with the same partner for their entire life. In other words, all swans have the same behavior, which can range from mating with the same bird for its entire life to mating just one or two years and finding different partners.
Some swans are even romantics who will play the field and have multiple partners.
Female Australian black swans (Cygnus atratus), for instance, choose a partner that they will stick with for years. But scientists did DNA testing on the eggs and found that one in six was actually fertilized by a male other than the female’s mate.
The male will even help incubate the eggs of the other male, probably without even knowing. We aren’t sure, since we can’t ask the males what they think.
In all species, if a pair doesn’t successfully lay and raise cygnets, the female may abandon the male to find a better partner.
When Do Swans Mate?
Swans don’t begin mating for years. Trumpeter swans (C. buccinator) usually wait until they’re four-seven years old to mate, but they’ll pick a mate a year or two before that. Trumpeter swans might pair up as young as their second winter.
Once the swan has chosen a mate, it will usually breed in the spring. In the northern hemisphere, that means sometime from April to June. Some will continue breeding into summer.
How Do Swans Mate?
Now that the swans are paired up and sexually mature, it’s time for the act itself. Most species face each other and slowly flap and shake their wings at each other, all while dipping and raising their heads. Then, they move closer and press their chests together and stare in each other’s eyes.
Now comes that classic twining of necks.
If the female allows all this, the male will mount her. He will stabilize himself by grabbing her neck, and she will raise her tail to give the male’s phallus access to her cloaca.
The actual copulation lasts just a few seconds, but the whole ritual can take over an hour. They may repeat the process a few more times.
How Often Do Swans Mate?
Swans only mate one time a year, but they’ll mate several times to ensure fertilization. Then, as we mentioned, the swans in a pair will often find another partner during the mating season to mate with. They’ll return to their chosen partner after breeding, however.
Both the male and the female will incubate the eggs and care for each other for the 35-41 days it takes for the cygnets to hatch.
So while they only mate during the spring in order to raise one set of chicks, they will mate several times during that period to ensure good fertilization.
Swans can live up to 30 years, and they’ll mate from the age of a few years old to nearly the end of their lifespan. That can mean dozens of matings and dozens of seasons of raising chicks for each bird.
What Happens If a Swan Loses Its Mate?
If a swan’s mate dies, the surviving mate will mourn the loss. They will stay in the location where they lived with their mate for days. One swan held up 23 trains in Germany for an hour after its mate died. The surviving swan refused to be moved and firefighters eventually had to come in and forcibly, but safely, remove the swan.
After the surviving bird decides to move on, it will join a new flock or find a new mate.
If the mate dies while the pair was raising their cygnets, the surviving mate will stay with the chicks and continue raising them alone.
After the young birds have left the nest and are old enough to survive on their own, the surviving bird will find a new mate.
Do Swans Mate with Other Birds?
In most species, the females and males will have one partner, but they’ll have multiple sexual partners over their lifespan. That means one clutch of chicks can be made up of eggs that were fertilized by several different males.
The whole group of chicks is raised as one by the male, with no discernment of who fathered the chick.
Then there are the birds who divorce each other. We don’t always know why, but sometimes the pairs will decide to separate and find new mates.
Audubon reports that three percent of mute swans (C. olor) will divorce for no discernable reason, and nine percent of pairs who fail to breed will divorce.
This practice is known as being socially monogamous, but not sexually monogamous.
