COUNTRY SIGHTS AND SOUNDS: Black-headed seagulls are back with a bang

We can hardly believe they are back, and in such numbers! A great crowd circled high overhead, screaming glad tidings to one and all. I knew what they were up to – water-born flies are hatching in throngs to be carried high by updrafts of air, where they are picked off by those hungry birds.

It was enough to see them as a distant, swooping, white-winged cloud, but I could scarcely watch when they converged on my little corner, darting and diving to snatch the living mid-air.

Now see those colours, close up! From more than a few yards they are, as their very name suggests, black-headed gulls. Seen properly their heads are dark chocolate, their black eyes red-rimmed and circled with white, legs and bills blood red. Despite these brilliant colours it is white that stands out; how clean, how clear, the epitome of pureness.

This image won't last year-long though. Looking after a family of young gulls is a messy business, as summer plumage will yet testify.

A solitary hooded crow flew into their midst, no doubt wondering what all the fuss was about. If there is food to be had, he will be there. Several of the gulls made preemptory swoops against this interloping larger bird. I thought they might strike – they were close enough to do so – but they turned aside repeatedly while the crow turned to fly among them.

Something must have happened. Perhaps the crow had his tail tweaked, or perhaps one of the gulls flew a little too close. Whatever it was, the crow was suddenly outraged. With a series of guttural cries it launched itself into the crowd, singled out one particular bird and pursued it at length, at moments no more than a foot behind.

The chase went on for a minute or more before the wings of the assailing bird carried him away. No doubt he will visit the gull colony again when there are eggs or young birds to thieve.

These gulls have been gathering slowly, with their numbers gradually building over the last month. Having spent the winter and early spring travelling the land and feeding where they may, their thoughts are now turned to summer breeding. They nest on small, rocky islands hereabouts, creating loose, shallow bowls comprised of dead vegetation. Two or three eggs is their lot, with two broods being quite common and a third a distinct possibility if food is plentiful and the weather kind.

Some female black-headed gulls will lay at least some of their eggs in the nest of another, and leave the foster parents to care for the hatchlings.

It is the rich supply of high-protein insect food that brings generations of gulls back here to breed year on year. The adults fill their crops with these and regurgitate them onto the ground for their family to pick over. As we said, it's a messy business.

Even as the gulls are arriving, so the whooper swans that came here for the winter are turning for home. That same evening a flock two score strong flew to the north, eager for clear and cool Arctic air.

Lightly coloured by the sinking sun, they flew low, no more than a few meters above the treetops, leaving their soft, musical voices to dissipate over the bay.

There must be a lesson in the way they organize themselves for the arduous journey that lies ahead.

No doubt there are individual birds that could fly more strongly than their peers, that could push

ahead and leave the majority trailing behind. Yet they don’t do that.

Each bird takes position in that classic V formation, taking advantage of the slight uplift provided by the wings of the one ahead. There is no rush, no element of competition. Each does his best for the migrating flock, taking turns to work hard at the front and then an opportunity to rest in the slipstream of another.

Things change once they reach Icelandic shores, when the stronger among them quickly become dominant and secure the best breeding territories close to prime feeding locations. In this way, the stronger swans enjoy increased breeding success and will be in better condition when the time comes to return to Mayo next autumn.

By the time they arrive, our gulls will have dispersed once more, leaving the lake and the surrounding land to the whopper swans. These moments pass far too fast.