The Nonsuch Island Cahow-cam is up and running again as researchers hope to capture never-before-seen courtship behaviours.

The streaming camera, which is hidden inside a man-made Cahow burrow, has previously recorded the incubation of eggs, the hatching of a Cahow chick, the feeding of the chick and the behaviour of the young bird.

However, one element that has never been captured is the courtship behaviour of the rare and indigenous birds.

In an online post, conservation officer Jeremy Madeiros wrote: “The Cahow is a pelagic seabird, meaning that it spends its entire adult life living on the open ocean, usually well out of sight of land, feeding on squid, fish and shrimp-like organisms.

“Pelagic seabirds, in fact, do not really need land for anything except as a place to lay their eggs and raise their chicks, usually on isolated, predator-free islands. Geolocator tags fitted to the legs of a number of adult Cahows from 2009 to 2011 revealed that they usually spend the non-breeding months (June to October) either 2,500 miles northeast of Bermuda, near the Azores Islands, or in the area between North Carolina and Nova Scotia.

“It also revealed that the male and female birds are usually separated by thousands of miles during this time, and probably never see each other except at the breeding colony. Since it is virtually impossible to see normally what is happening inside the deep, pitch-dark nest burrows that the Cahow nests in, the Cahow-cam affords a unique opportunity to unravel this chapter in the life of Bermuda’s unique, and critically endangered, National Bird.”

This year, the camera has been set up on a burrow for the start of the bird’s nesting season, and Mr Madeiros said they hope to capture the reaction of the Cahows when they return, courtship and mating behaviour, next-building activity and other undocumented behaviour.

“This period will last up to early December, when both adults usually start the ‘exodus’ period, returning to sea for four to five weeks to feed intensively, for the female to develop the egg growing in her, and the male to pack on fat deposits so that he can take on the majority of the egg incubation duties, sometimes going for two weeks or more without food during the lengthy 53-day incubation period until the chick hatches.

“The next time we will see the adults is in the New Year, when they return in early January to lay their single large egg and begin the incubation period.”

The Cahow, or Bermuda Petrol, were believed to be extinct for several centuries before they were famously rediscovered in 1951. Since then efforts have been made to save the species, including recently translocating birds from the rocky isles where they have nested to artificial burrows on the Nonsuch Island Nature Reserve.

The programme has so far been largely successful, increasing the population from just 18 nesting pairs, producing just eight fledglings a year, to 112 nesting pairs who successfully hatch more than 50 chicks a year.

• To view the live Cahow-cam online, visit the Nonsuch Island website at www.nonsuchisland.com.