Bermuda’s national bird has returned to Nonsuch Island, with cahows laying the first eggs of the season.

The Nonsuch Expeditions Blog reported that while rough weather had limited access to the island, researchers found on January 4 that the first cahows of the season had returned to their burrows to lay eggs.

Jeremy Madeiros, senior terrestrial conservation officer, wrote: “In two burrows, single adult cahows were incubating the first confirmed eggs of the season, while in two other nests, pairs of adult cahows were together in the nests but had not produced eggs as of yet.”

They returned to Nonsuch Island on January 6 and found that two more cahows had returned to the two colonies on the island and recorded additional eggs.

Action on CahowCam1, a research camera hidden in a cahow burrow which broadcasts online, picked up shortly after 11pm on January 6 with a female cahow returning to the burrow and laying an egg minutes after midnight.

Mr Madeiros said: “Then, as to emphasise how well-synchronised these birds are after being separated by hundreds of miles at sea for the last five weeks, the male bird arrived at the nest at about 1.49am, with the birds mutually preening each other and the male trying to convince the female to relinquish the egg so he could begin his incubation ‘shift’.”

Mr Madeiros said that as of January 9, cahows had returned to nine of the 40 burrows on Nonsuch Island.

Cahows, also known as the Bermuda petrel, were largely wiped out by introduced predators and hunting by early English colonists. 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.

In 2023, researchers recorded 156 breeding pairs with 76 successfully fledged chicks across six islands, including Nonsuch Island.

This year’s breeding season began in late October and November last year, when the birds returned to the island for courtship, nest building and mating before returning to the sea for four to six weeks for what is described as a “pre-egg laying exodus”.

They then return at the beginning of January, with mating pairs often arriving within hours of each other back at their nest burrows.

Mr Madeiros said weather conditions so far this winter had been unusually wet and windy, allowing visits to the Castle Harbour Islands one or two days a week in between weather systems and the strong to gale-force winds that they often brought.

For more information, visit www.nonsuchisland.com.

• UPDATE: this article has been updated with links to the Nonsuch Expeditions website