Researchers studying Bermuda’s national bird have found themselves investigating a soap opera drama among cahows on Nonsuch Island.

While the critically endangered seabirds are typically monogamous, a clash between two males caught on camera has sparked questions about which bird is the father of a recently hatched chick.

However, a genetic population study is expected to provide an answer — along with unveiling more about the genetic diversity of the species and how it survived in secret for centuries.

JP Rouja, the founder of Nonsuch Expeditions, said: “For a species that is thought to be generally monogamous, how much of this has been going on?

“They experienced a near-extinction bottleneck event in the 1600s, and then barely survived with a hidden population of a few dozen for over 300 years.

“One would expect much higher levels of inbreeding during the bottleneck, which this genomic population study should help explain.”

Jeremy Madeiros, the chief terrestrial conservation officer, said the infidelity drama began to play out on CahowCam2 last October.

He said that one of the birds, Sampson, was among several chicks translocated from Horn Rock to Nonsuch Island in 2005.

Sampson originally paired with a female cahow named Susie and the pair successfully fledged 12 chicks over the next 14 years.

However, Susie did not return to the island for the 2023-24 breeding season and is suspected to have died at sea.

“Sampson returned and waited for a month for the return of his mate, however, such an eligible bachelor was sure to attract the attention of the ladies,” Mr Madeiros said.

“By late November, 2023, he was joined in the nest by a new, young 5-year-old female cahow that had fledged from Horn Rock in 2018.

“After initially repelling her advances, he eventually accepted her and they produced their first egg in 2024, which in common with most first eggs produced by first-time breeding females, did not hatch.”

Mr Rouja said that the researchers expected the pair to reunite this year and were monitoring the burrow on CahowCam2 when a cahow arrived “earlier than expected” on October 27.

The following day, a second cahow arrived at the burrow, and the pair was recorded mating.

“When Jeremy and I were next able to get out to Nonsuch on October 29 he found that as expected one bird was the new female, but was surprised to find that the male was not the resident Sampson, who had yet to return,” Mr Rouja said.

“As Jeremy predicted, the following night we were then able to witness via the CahowCam the return of Sampson and, after a fight, the prompt eviction of the smaller interloping male, after which Sampson was seen to settle in with his younger mate.”

The female subsequently laid a single egg in January, which hatched on March 9.

Mr Rouja noted that the “interloping male” was later identified and it was found that he had moved to his original nest with his original mate, and the pair had produced their own chick.

The soap opera drama will have an answer as Nonsuch Expeditions partnered with Carika Weldon, the founder of CariGenetics, to launch BioQuest, an organisation focused on using genomics to assist with conservation.

Mr Rouja said: “We have already produced the reference genomes for the grooved brain coral, Bermuda skink, and of course for the Bermuda petrel, or cahow.

“BioQuest has now embarked on a genomic population study of the entire cahow population, and has already sequenced the first 50 samples out of about 350 birds.

“In the immediate future, we will include a sample from this season’s chick and its potential half-sibling in the burrow further up the hill, giving a definitive answer to Jeremy’s parentage concerns, which he would have otherwise been unable to prove.”

Dr Weldon said the genetic sequencing will be able to identify how all of the cahows are related with each other.

“This will help us to understand the genetic diversity of the current population — the more diverse the healthier — the inheritance of certain traits that may have helped them to survive and inversely why some pairs are less successful,” she said.

“There will be no dramatic reveals on camera, however, this will allow the conservation team to piece together the huge picture of how a species thought to be extinct for 350 years could survive and thrive so well today.”

Mr Rouja added: “Whilst we won’t interfere with already existing pairs, had we had access to genomics prior to the initial translocation effort 20 years ago, this might have influenced which birds were selected for translocation.

“Lessons learnt here may help with the planning for similar programmes and the recovery and management of similar species in the future.”