After a failed first nesting attempt, a pair of rare seabirds are set to become parents any day now.

The pair — one of only three breeding pairs of common tern in Bermuda — lost their first batch of eggs when a boat tied up to their nesting site.

Former conservation officer David Wingate yesterday appealed for the public’s assistance to make their second attempt a success.

“They are so determined to succeed that when I made my last check to count and measure the eggs, one bird actually landed on the head of my assisting colleague, Miguel Mejias, as if to plead mercy when its vicious dive bombing attacks in defence of its nest had failed to deter us,” Dr Wingate said.

The pair of common tern, which can be told apart from the longtail by their buoyant graceful flight, red bills and legs, black caps and forked tails, had been trying to nest on a buoy in St George’s Harbour.

According to Dr Wingate, their first attempt failed when a boat tied up to the buoy — despite a warning sign installed by Conservation Services identifying it as a nesting site — during the dinghy racing event on May 24.

“This prevented the adults from attending their nest, with the result that the embryos died only a few days before they would have hatched,” Dr Wingate said. But he added that the pair has laid again and the eggs are expected to hatch any day now.

Dr Wingate urged boaters to keep clear of the posted buoy to give the birds a chance to succeed — “notwithstanding that you would be liable for fines up to $10,000 if convicted for harming them deliberately”.

He said: “The common tern has since time immemorial been a conspicuous summer resident of our inner harbours and sounds, where it dives to feed on small bait fish and nests on small rocky islets.

“It would be an absolute tragedy to lose this population, which our ongoing research has recently confirmed to be an endemic race, unique to Bermuda.”

Although the common tern has “never been a common bird here”, Dr Wingate said “earlier generations of Bermudians knew it as the ‘redshank’ and valued it as a guide to where the bait fish schools were located”.

Dr Wingate has been tracking the population since the 1960s and recorded between 18 and 35 breeding pairs annually up until 2003, when Hurricane Fabian wiped out the males and chicks.

The females, who migrate to their South American winter quarters much earlier than the males, survived and returned to lay their eggs the next year.

“But of course none of them were fertile resulting in total breeding failure,” Dr Wingate said.

Although the population began to recover, it was decimated by another hurricane in 2008. Only three viable pairs now remain, two of which have already successfully reared a total of four fledglings this year.