A rare local seabird is pulling back from the brink of extinction thanks to a “100 per cent successful” breeding season.

But conservationist David Wingate warned that the survival of Bermuda’s three remaining pairs of the common tern remains precarious.

“We can only pray now that no new hurricane will hit Bermuda this year to undo this small incremental step to recover,” Dr Wingate said.

“It is quite possibly the last chance that this most beautiful and graceful addition to our summer harbour scene will have to recover.”

The migratory bird thrives around the world, but the Bermuda population, which DNA analysis shows to be endemic and distinct, was almost wiped out by Hurricane Fabian in 2003.

Since then, a string of direct hits from hurricanes have kept their population dangerously low.

Sterna hirundo has been protected with the help of Bermuda Maritime Operations, the marine police and the local boating community, who have kept “a respectful distance from their vulnerable sign posted breeding sites in St George’s and Hamilton harbours and in Little sound”, Dr Wingate said.

“Two of these sites were abandoned ship buoys dating from the period of US Navy occupation between 1941 and 1995, which had to be modified into mini-islands by the addition of sand, perimeter rock barriers and shade covers.”

Terns typically lay eggs in clutches of three. Nine birds fledged successfully this summer and have been ringed or banded for identification.

Unlike the success story of the cahow, local terns are at the mercy of the elements before they head to their wintering grounds in South America.

“Data from 45 years of monitoring has revealed that every time Bermuda is subject to a direct hit by a Category 2 hurricane or higher, the entire fledgling crop and most, or all, of the male adults are wiped out,” Dr Wingate said.

“Partly for this reason, the tern has never been very common on Bermuda. Over the last 50 years, the maximum number of pairs was 35, attained in the early to mid-1980s at the end of a very long cycle of low hurricane activity in the Atlantic basin.”

Global warming, which is expected to intensify hurricanes, could “easily tip the scale towards extinction of the local population”, Dr Wingate added.

The last chicks to fledge, on the ship buoy in the Little Sound, developed their adult feathers just before Cup Match.