Terns get a little help from friends

THERE’S good news on the bird front; little terns seem to have bred successfully this summer.

Not much bigger than a starling, this is the smallest of our five tern species. It’s also one of Ireland’s rarest and most vulnerable seabirds. A survey carried out by BirdWatch Ireland suggested that we had about 500 adult birds in 1995.

Sometimes called ‘sea swallows’, terns resemble delicate little gulls with black skull-caps. The plumage is pale grey above and white underneath. You can tell the little tern from its cousins by its smaller size and yellow bill. Terns spend the winter in tropical waters, coming to Ireland in summer only to nest. The season has just ended; little tern families, and some lone birds, are beginning their journey to the coast of Africa. The adults will be back here in April or May, but this year’s youngsters won’t return until the following year.

Little terns are pernickety when it comes to choosing nesting sites. In Ireland and Britain, they seek out coastal shingle beaches, or shell-strewn sandy places, with stretches of clear water, salty or fresh, close by. There has to be a plentiful supply of little fish with which to feed the chicks.

Unfortunately, humans like to visit such places in summer and disturbance by hikers, sunbathers and dog-walkers makes life difficult for the terns. Between 1968 and 1972, there were 16 colonies along the coast between Dublin and Waterford. Only eight of them remained in 1987, increased disturbance being to blame. No nest is built; the eggs, beautifully camouflaged, are laid on the ground among pebbles and broken shells. People walk on them, or on the chicks, inadvertently. The conflict of interest between the terns and ourselves has become so acute that, according to Niall Hatch of BirdWatch, “the bird can’t survive here without human help”.

But all is not lost. Terns tend to nest in loose colonies and they do so at the same locations year after year. BirdWatch has identified the sites; there are about 23 of them. By cordoning off the most important locations and employing wardens to protect them, the organisation has managed to maintain a viable population.

The largest Irish colony is near Kilcoole in Co Wicklow. BirdWatch, supported by the National Parks and Wildlife Service, began wardening there 25 years ago. A caravan is brought to the site in spring so that wardens can keep watch day and night. When the terns arrive, notices are placed, alerting people to their presence.

Humans are not the only threat. Foxes and grey crows target eggs and chicks. So do kestrels and peregrines. Disused telephone cables, running beside the nearby Dublin-Rosslare railway line, provided perching points for predators to launch attacks on the colony. BirdWatch had the wires removed. Posts around the site have bits of plastic, which flap in the wind, nailed to them so that crows won’t alight. Wire netting placed around nests can keep foxes out.

There have been some unlikely intruders. Badgers will eat eggs and a hedgehog almost cleaned out the colony on one occasion. The wardens managed to catch the looter in a cage trap and take it to a suitable location, many kilometres away, where it was released. Otters frequent the salt-marshes inside the shingle bank. These are not averse to eating birds’ eggs but, according to Niall Hatch, they are a lesser of evils as far as the terns are concerned. Their presence, he claims, discourages a much more voracious egg and chick predator, the mink.

In some years, up to 10% of nests were lost to flooding when freak waves swamped part of the colony during high tides with off-shore winds. Wardens have successfully moved nests, a tiny bit each day, until they are well clear of the highest tide line.

Niall Hatch told the Mooney Show that 99 pairs nested at Kilcoole this summer, raising 160 chicks. Figures for the rest of the country are not available yet, but initial reports suggest that the season has been a good one. Well done, BirdWatch and the NPWS!