A “wealth” of new information about Bermuda’s national bird has been uncovered as part of a collaborative biomonitoring research project.

JP Rouja, the founder of Nonsuch Expeditions which is involved with the study, provided an update on the findings which shed new light on the cahow’s biology, feeding and foraging strategies, and at-sea range.

Mr Rouja has worked with Jeremy Madeiros, a terrestrial conservation officer with the Department of Environment and Natural Resources, as well as a team of international researchers on the Bermuda Petrel Biomonitoring Project.

The project, which focuses on the critically endangered pelagic seabird, has run since 2019 and continues to “bear fruit”.

The latest findings show that the cahow — also known as the Bermuda petrel — embarks on extensive foraging trips lasting up to ten days on average and taking in approximately 750 miles, while during foraging trips, cahows spend over 75 per cent of their time in flight.

They also showed that cahows engaged in very limited diving activity leading, along with other data, to the conclusion that the birds are overwhelmingly nocturnal surface feeders.

Mr Madeiros highlighted in a social media post that the level of research required to “make this work a reality, and some of the amazing new findings that are unravelling the story and life of Bermuda's amazing, iconic national bird”.

In June, the group published a peer-reviewed research article in the journal Ecology and Evolution titled Fine-Scale Movement Data Reveal Primarily Surface Foraging and Nocturnal Flight Activity in the Endangered Bermuda Petrel.

Authors included Mr Madeiros; Paolo Becciu of the Department of Ecology and Evolution at the University of Lausanne, Switzerland; Allison Patterson of the Wildlife Research Division of the Department of Environment and Climate Change, Canada; Carina Gjerdrum of the Canadian Wildlife Service, Canada; and Letizia Campioni of the Marine and Environmental Sciences Centre, Instituto Universitario, Portugal.

The project was carried out during the egg incubation period of the cahow's breeding season in January and February 2023, and involved deploying 25 miniaturised multi-sensor biologgers to the back feathers or central tail feathers of selected adult cahows.

Biologgers, which have been fitted for periods of up to a year, help to identify oceanic range during the non-breeding period.

Mr Madeiros said that the data explained the cahows’ “superpower” of being able to travel such long distances from the breeding colony in Bermuda over remote oceanic regions.

He said: “During foraging trips, cahows spent over 75 per cent of their time in flight, mainly in dynamic soaring flight.

“Dynamic soaring is a very energy-efficient flight technique used by petrels such as the cahow and was the most common flight behaviour used under all conditions.

“Flight increased during dusk and at night, showing greater activity at night compared to the day, while water surface behaviours were more common during the day.”

Mr Madeiros added that there was strong evidence that cahows actively seek out favourable wind conditions, such as the strong winds around winter storms, to enable them to cover such huge distances.

He added: “Evidence showed that cahows engaged in very limited diving activity. Less than 0.001 per cent of depth measurements from eight cahows exceeded 0.1 metres, with the maximum depth recorded at 1.57 metres.

“There were only five dives deeper than 0.5m …

“The results show that cahows are overwhelmingly nocturnal surface feeders, only rarely engaging in shallow diving during their extensive feeding trips on the open ocean.”

Adult and fledgeling cahows sometimes regurgitate when being handled.

Using advanced techniques such as DNA metabarcoding, it was discovered that cahows eat up to 16 species of deepwater bathypelagic fish and nine species of mainly deepwater squid which migrate to the surface at dusk.

Mr Rouja said: “This collaboration is yet another example of how global partners and the latest technology unlocks previously impossible-to-obtain insights into their secret lives.

“Another offshoot of this project is the genomic population study being conducted with local partner BioQuest, initiated using leftover ‘remnant’ blood samples, sent back to Bermuda after originally being drawn for the persistent organic pesticides portion of this study.

“These are being sequenced locally in the BioQuest lab at the Bermuda College, a groundbreaking first for Bermuda and the Caribbean region.”

Mr Rouja said updates will be posted on the Nonsuch Expeditions website including the answer to the “who’s the daddy drama” from the past cahow nesting season. There had been some uncertainty as to the identity of the father of a chick named Inna.

Cahows are commonly seen on the southern tip of Cooper’s Island in St George’s in the late afternoon in November and January to March, according to the Bermuda Audubon Society.

• For more information on the project, visit nonsuchisland.com