A cahow made an unexpected appearance off the coast of Massachusetts. Cahows, also known as Bermuda petrel, are indigenous to the island, but spend most of their lives at sea.

The sighting was made during an offshore pelagic birdwatching trip to the continental shelf around 140 miles southwest of Hyannis, organised by the Brookline Bird Club.

Jeremy Madeiros, a principle conservation officer for the Department of Environment and Natural Resources, said he was excited to learn about the sighting. He said: “It of great interest to me as it provides confirmation of data we are getting from advanced GPS tags fitted on adult cahows nesting on Nonsuch Island.

“This project was carried out earlier this year by two overseas groups of researchers, in partnership with the Cahow Recovery project managed by the Department of Environment and Natural Resources.

“One of the first tags which was recovered this spring from a male Cahow nesting on Nonsuch recorded a six-day feeding visit to Massachusetts waters, not far from this siting.”

Mr Madeiros said the tag had shown the bird had flown to Georges Bank, about 100 miles southeast of Boston, over the course of two days.

“After spending two days on the bank catching squid and fish, it then returned to Bermuda, hitting speeds of nearly 50mph and covering a total of 1,600 to 1,800 miles. Being photographed and confirmed by groups such as this provide ground-proofing and further important confirmation that this is an important feeding ground for our far-travelling national bird.”

Jean-Pierre Rouja, team leader at Nonsuch Expeditions which collaborated on the GPS-tracking project, said: “We filmed the groundbreaking GPS-tracking efforts this past Spring to be included in an upcoming film. The tracking results will be incorporated in the curriculum that we are developing with the Cornell Lab of Ornithology.”

Once common in Bermuda, the cahow was believed to have been wiped out after British settlement. But the species was rediscovered in 1951 and has since been the subject of a long-term management and recovery programme.

As a result, the population has risen from just 17 or 18 nesting pairs to 131 nesting pairs, and the number of chicks raised every year had risen from seven or eight in 1962 to 73 this year.

Mr Madeiros said: “I think that as the cahow population has slowly increased, and interest in oceanic seabird watching has also increased, we have been seeing more of these sightings.

“In fact, several years ago photographs were taken of a cahow in Irish territorial waters over 3,000 miles to the northeast.

“Despite this, the cahow remains one of the rarest seabirds on Earth, with a tiny overall population.”

• More details about the tracking programme can be found at www.nonsuchisland.com