Bird watchers spotted a cahow off the coast of Ireland on Monday.

The sighting marks the farthest Bermuda’s national endemic bird has ever been observed, Dr David Wingate confirmed yesterday.

“This is the most remote sighting we have seen so far,” said Dr Wingate.

Maps produced by geolocation tags attached to 12 cahows have shown the birds reaching as far as Ireland, but an actual sighting, said Mr Wingate, is just as rare as the bird itself.

With between 300 and 350 cahows spread out over millions of miles of ocean, to spot a single cahow as far away as Ireland, Dr Wingate said, is “incredibly exciting.”

“The chances of encountering [a cahow] is a million to one, so that’s what amazes me about [the sighting.] I suspected we would see it further down the road when the population grows more, in about ten years, but not this soon.”

The Bermuda Petrel, commonly known as a cahow, was seen by cetacean and seabird surveyors on board the research ship RV Celtic Voyager, some 170 nautical miles west-northwest of Slea Head, on the south-west tip of the island.

Dr Wingate said the location of the sighting is very near to the continental shelf, which would explain what the cahow was doing there in the first place. Cahows, he said, look to take advantage of nutrient-rich waters where fish stocks are more abundant. And as the nutrient-rich Gulf Stream waters rise to the surface, forced up by the shelf, with them come the fish that eat the plankton, and then the birds that eat the fish.

“One hundred and fifty miles offshore is about the edge of the continental shelf, where it drops off into deep water. They don’t usually go much outside of there and that’s about as close as we’d expect them to get to Ireland.”

The sighting signals a strong return for the cahow population, in what Dr Wingate called one of the greatest conservation success stories in the world.

Referring to the Sea Venture that shipwrecked on Bermuda’s reefs in 1609 and led to the permanent settlement of the Island, he said: “When the Sea Venture left [England]they were probably seeing cahows at sea all across the Atlantic. They could have seen them circling around the ship across the Atlantic without realising this is a bird endemic to Bermuda.”