Cahows have started their return to Bermuda despite storm damage to a handful of burrows.

Jeremy Madeiros, principle scientist, terrestrial conservation, Department of Environment and Natural Resources, wrote on the Nonsuch Expeditions blog that despite a series of near-misses, storms had done only minor damage.

“Only a minor amount of damage was caused to cahow nest burrows on the smaller exposed nesting islets, involving the replacement of one concrete nest lid washed overboard, minor damage to the entrances of two concrete artificial nest burrows and clearing of stones and other debris washed into the nests by waves on two of the lowest elevated islets,” he said.

“The largest nesting colonies on Horn Rock and Nonsuch Island were relatively unaffected.”

Mr Madeiros said the seasonal return of the seabirds was “well under way”, although the strong winds and storms had limited visitor access to the island.

On October 19, when Mr Madeiros went to Nonsuch to release two injured longtail chicks, he said he checked up on three adult cahows that had already returned to the island, including one returning to Bermuda for the first time since fledging in 2018.

“On October 23, I was able to get out to Nonsuch for a couple of hours following meetings and confirmed that more cahows were taking advantage of the continued rough, breezy conditions to return,” Mr Madeiros added.

“At the B cahow colony, although at least three nests had been visited, only one adult cahow had stayed over in the nest for the day.

“Over at the A cahow colony, at least another seven nests had returned cahows in residence, although time restraints only enabled me to check the birds in a few of them.”

One of the burrows found occupied was one monitored through the CahowCam project, which uses small cameras to livestream activities within the burrow.

Mr Madeiros said both birds were in good physical condition, and the pair had successfully fledged seven chicks since 2010.

“They have a long record of nesting successfully one year then failing the next, and as they failed earlier this year, hopefully this means that this nesting season they will be successful again,” he said.

Cahows, also known as Bermuda petrel, were largely wiped out by introduced predators and hunting by early English colonists, and by the 1620s the species was believed to be extinct.

However, the species was rediscovered in 1951, with a handful of the birds found nesting on four rarely visited rocky islets, sparking efforts to rebuild the population.