Whooper swans trumpet their arrival

I HEARD an unmistakable sound — a wild trumpeting filling the sky.

Jim Wilson in his recent book Freshwater Birds of Ireland describes it as being like an out-of-tune wind instrument. I think this is a little harsh because for me it’s one of the most beautiful of all bird calls. I looked up and 30 or 40 whooper swans were flying overhead in a V formation.

An estimated 12,500 whooper swans spend the winter in Ireland. They come from western Iceland to Ireland and western Scotland. Birds from eastern Iceland spend the winter in eastern Scotland and southern Scandinavia. When the Irish birds first arrive they congregate in large flocks on Lough Foyle and Lough Swilly. Later in the winter they break up into groups, like the one I saw the other day, and head further south. Most of them leave again in March or early April.

Occasionally a swan will not make the return journey, possibly because it’s suffering from a minor injury that would make the long flight too hazardous. I’ve seen them on the Shannon in summer and every year since 1992 between one and three pairs have bred in north Donegal. There are also records of whoopers mating with resident mute swans and successfully rearing a hybrid brood. The main visual difference between the two species is that the whooper has a black and yellow beak and the mute’s is black and orange.

It really is a difficult journey between north Donegal and west Iceland at seasons of the year when the north Atlantic weather tends to be very turbulent. It’s about 1,300 kilometres. In ideal conditions the birds can do it in 13 hours because they’re fast fliers. But it can take several days. They normally fly in a V formation and the bird at the point of the V is changed regularly so that it can rest in the slip-stream of the others. Pilots have observed them at an altitude of 8,000 metres. Up until about 10 years ago a flock of whoopers, usually containing 52 birds, used to winter on a small lake near me. They are normally very site faithful so I was apprehensive when they failed to turn up one winter. Shortly afterwards I learnt that Bord na Mona had developed some lakes on cutaway bog at Boora in the neighbouring county of Offaly and that a flock of 52 whooper swans had suddenly turned up there. Obviously Bord na Mona stole my swans.

I I found them very interesting birds and I was aware that in winter, Ireland holds about 20% of the world population. One thing I noticed about them is that, unlike mute swans, they preferred to feed on land. Round here they particularly liked to graze on winter cereals. I only recently learned that this is a relatively new phenomenon.

Whooper swans have been increasing in numbers for the past 30 years, both in Ireland and on their breeding grounds in Iceland. The other wild swan that visits us in winter, which I call a Bewick’s swan despite the fact that an international conference of ornithologists has recently changed its English name to the tundra swan, is steadily decreasing in numbers in Ireland.

* dick.warner@examiner.ie

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