The Island is full of hopeless romantics and they are concerned.

It isn’t their own love lives about which they are fretting, but about another animal’s partner predicament. By far, one of the more common calls we received at Felix Neck Wildlife Sanctuary come from folks worried about lonely swans. Why is there only one swan in the pond, they ask, and where is its mate?

Perhaps I shouldn’t be surprised by this inquiry. The group Three Dog Night memorably crooned, “One is the loneliest number that you’ll ever do,” and everyone seems to be familiar with the fact that swans are notorious for not being single.

Swans are symbols of love and fidelity, and are famously known to mate with one partner for life. Shakespeare cited this reputation in As You Like It:

 . . . we still have slept together,
Rose at an instant, learn’d, play’d, eat together,
And wheresoe’er we went, like Juno’s swans,
Still we went coupled and inseparable.

So it is not surprising that people are anxious when they see a single swan. It is also okay; the single swan may not be in for a life of loneliness.

It is possible that one of the swan couple is out of sight, lingering nearby. However, as in the case of even the most solid couples, separation and even divorce is possible for swans. Some swan species even swing.

Studies show that in the notably monogamous swan species, up to nine per cent of couples can split up. In one species in Australia, one out of seven eggs in the nest is the offspring of a different male than the others. So much for the monogamy myth.

There are reasons for swan break-ups and it is mainly about procreation. If swan duos are unsuccessful breeders, they are more likely to split than their fruitful friends. Even those that have breeding success can end up separating. This happens in about three per cent of swan relationships, while swans that failed to procreate have a higher rate (nine per cent) of splitting.

Interestingly, after a separation the female swan is more likely to find another mate, often in less than three weeks, while the male may have to wait till the next season to hook up with a new squeeze.

There are even stronger motives for swans to stay together — protection and parenting top the list. Though they are large birds, there is strength in numbers and two swans are better than one when it comes to safety. Additionally, established pairs learn to parent and improve year after year, and that can increase the survival rate of their offspring.

Regardless of the few outliers that break up, till death do them part is generally the swan way of life. In some cases, only mortality will separate a swan pair. When one dies, the other may grieve, but the surviving spouse can and will go on. Even if a swan dies during nesting season, all is not lost. Either sex can continue to parent, since both the male and the female incubate the eggs and rear the chicks, called cygnets, and both are able to take care of themselves and their chicks as single parents when necessary.

The next time you see swans entwined, it will no doubt conjure up thoughts of love. And if you see a lone bird, perhaps it will cause you to reflect on loss. Their single and paired conditions, after all, well reflect some of our own amorous trials and tribulations. But the hopeful among us should remember that even a sighting of a lone swan may not indicate the relationship’s or the individual’s swan song.

Suzan Bellincampi is director of the Felix Neck Wildlife Sanctuary in Edgartown, and author of Martha’s Vineyard: A Field Guide to Island Nature.