A whooper of a love story

WHOOPER swans Romeo and Julietta are in the news.

Like most of their tribe they would spend the summer in Iceland. In winter they moved to Britain, where their preferred haunt is the Wildfowl and Wetlands Trust reserve at Welney in Norfolk.

As is the case with swan couples generally, the two are devoted to each other. All was rosy in the garden until a year ago.

Then disaster struck; Julietta injured herself and could no longer fly. Travelling 1,800 km to Iceland last spring was not on. But what would Romeo do? Injuries such as Julietta’s are relatively common; swans often collide with power cables, breaking a wing. Flightless victims are usually abandoned by their mates, so it was expected Romeo would kiss his beloved goodbye andhead off.

Whoopers migrate in flocks and as departure time approaches birds become restless and agitated. The pressure on an individual to go with the others is intense. Nevertheless, Romeo stayed behind with his injured wife. Then an extraordinary thing happened; the pair nested on the reserve. Two cygnets hatched, one of which has survived. Although a few pairs breed in Scotland and some do so occasionally in Ireland, whoopers haven’t nested in Norfolk since 1928.

“If you want monogamy, marry a swan” the saying goes. Some swan species, however, are more dutiful than others. The familiar mute swan of Irish lakes and ponds, although never licentious, is rather more lax in its morals than the whooper. Of the 1,500 mutes I ringed in Dublin and Wicklow, 97% remained faithful to their spouse from one year to the next. It’s important to clarify what we mean by “spouse”; there are no marriage ceremonies or registrars for swans. Juveniles spend the winter in flocks, or herds, at traditional locations, ballrooms of romance for them. They have their courtship rituals and mating protocols just as we do; observe the behaviour of birds in flocks and flirtations soon become apparent.

Bonding is a slow process. Despite what the “family values” lobby claims, monogamy has its drawbacks. While it guarantees stability, helping the spouses to become an effective team, an individual may become hitched to a defective partner and fail to produce viable young year after year. It is crucial, therefore that a swan makes a wise choice.

In late winter or early spring, newly-formed pairs leave the flocks and seek out territories. Then comes the honeymoon year, during which swans copulate, make crude nests but seldom produce eggs; after the stresses of courtship and territory acquisition few brides are heavy enough to ovulate. Usually, the first eggs are not laid until the following year. On average, an Irish mute swan is five years old by then. Up to the arrival of eggs, the pair bond tends to be weak; there’s many a slip twixt cup and lip. If things don’t work out, birds may go their separate ways. However, once the pen is sitting on eggs and the cob is defending the territory, the parents are definitely an item.

Of swans which produced at eggs in Dublin and Wicklow, around 3% went on to have eggs with another partner while the original mate was known to be still alive. Although it took me many years to arrive at this statistic, it’s not a completely reliable one. Tracking ringed swans is difficult. It’s possible, with great effort, to log life histories for about one swan in three. The rest disappeared at some stage. A missing spouse may be dead or it may have flown away. You can only be sure a divorce has occurred when you know what happened to the spouse. The breakdown figures, therefore, are subject to bias.

It is even more difficult to monitor the social behaviour of the migratory whooper swans but studies indicate an even higher level of fidelity than among mutes, as the Romeo and Julietta story illustrates. Will their cygnet head for Iceland without its parents next month or will it too remain on in Welney?