Lovers’ quarrels and problem tenants have caused a dramatic start to the 2026 cahow nesting season on Nonsuch Island.

The Nonsuch Expeditions blog said that researchers watching the live-streamed CahowCam1 burrow saw one of the endangered seabirds lay its single egg for the year on January 5.

However, those who tuned in days later caught more excitement than usual with an “all-out, six-hour battle” between the female and her partner.

The Nonsuch Expeditions blog said that while the couple that occupy the burrow have been known to fight over who gets to incubate their egg, cameras on January 9 caught a distressing altercation between the pair.

While cahow pairs usually take turns incubating their egg, granting their partner an opportunity to feed and rebuild fat reserves, conflicts can arise when the birds are not in sync.

The blog, written by Nonsuch Expeditions founder JP Rouja, said: “In their case, her refusal to hand over results in arguments ranging from gentle nudging to passive aggressive shoving to full-on fights, which in some seasons have even contributed to the accidental failure of the egg.

“This current season, the night before he was officially logged as arrived, a male spent six hours at times violently battling her to take over the egg.

“This was very distressing to watch for the team and online followers, as it seemed to be a nest invasion. However, Jeremy believes that it might in fact have been him and she just wasn’t ready for his return, let alone for him to take over incubation.

“She pushed back and resisted in ways that would have been impossible or even fatal for a smaller female.”

The nesting couple also had to deal with another intruder — a red land crab that took up residence near the CahowCam camera itself.

While the crab was not considered a direct threat to the birds, who are known to chase such trespassers, a blog post noted that the crustacean was feeding off the nesting materials, potentially risking damage to the egg.

Jeremy Madeiros, terrestrial conservation officer with the Department of Environment and Natural Resources, said: “Unfortunately it has been coming out a lot and stealing a lot of the nest material, which is mainly bay grape leaves and grass, and dragging it into its burrow.”

While Mr Madeiros was unable to evict the crab during a visit on January 6, he replaced the stolen nesting material to better protect the egg.

He said: “Nests that don’t have a lot of nesting material and have stones and sticks and stuff incorporated often have a much higher egg failure rate because it doesn’t take much for a sharp little stone to punch a hole through an egg.”

Among the birds spotted on Nonsuch Island last fall was a young cahow named “Totoro”, the first fledgeling from the 2021-22 breeding season to return to the island.

Mr Madeiros said he had been looking out for birds from that season to make their maiden return, because 37 of the fledgelings were fitted with global location sensor tags.

The tags, provided by research partners Letizia Campioni, are capable of recording and archiving daily positions for periods of more than two years.

Mr Madeiros said: “This should solve the mystery of whether the fledgelings go to the same oceanic areas that the adult birds do, during the period where the young cahows spend the first three to five years of their lives before they return to look for nest sites and mates.”

He said Totoro, a young “prospecting” male cahow, was caught in a nest on Nonsuch on November 27, more than three years after he was first tagged on camera in June 2022.

Mr Madeiros said he removed the tag from the now-adult bird and provided it to Dr Campioni to extract the location data.

He said it is hoped that the data collected will help to fill in the gap of where young cahows go in the “lost years” between when they leave Bermuda and when they return in search of burrows and mates.

Data gathered from adult cahows have shown the birds travelling great distances across the North Atlantic, with one bird recorded venturing 57,000 miles between April 2009 and June 2010.

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

By the 1620s, the species was believed to be extinct.

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

As part of the project, man-made burrows were created on Nonsuch Island, with chicks translocated to the sanctuary in the hope that they would return to Nonsuch as adults.

The project has borne fruit, with a growing number of birds fledging on the island.

Last year, cahows enjoyed a near record-breaking year of a total of 78 chicks fledging in the 2024-25 season across all the colonies, just two shy of the most successful season, 2023-24.

• For more information, visit the Nonsuch Expeditions website at www.nonsuchisland.com