An unexpected visitor has been making itself at home in an abandoned cahow’s nest on Nonsuch Island.

Thanks to infrared “CahowCams” installed in the nests by Nonsuch Expeditions team leader Jean-Pierre Rouja in 2012, new insights are being gained into what happens after burrows are left vacant in the wake of nesting season.

Within an hour of the cahow chicks making their seasonal journeys, a Bermuda land crab arrived in the nest, which came as no surprise as one turned up last year also.

However, within three hours, much to the surprise of the expedition team, a completely new inhabitant showed up at about 4am in the morning — what is believed to be a small petrel bird. It entered the nest to see if it could make an adequate home. The bird has returned for four successive nights to date to rearrange the nest material and to attract a mate.

Mr Rouja said: “This year we left the camera running after the chick had fledged on June 5 to see what happens immediately after the burrow is abandoned, and sure enough as happened last year, within an hour a land crab made its way into the burrow to start feeding on the nesting materials.

“To our utmost surprise, however, around 4am a small petrel-looking seabird first called into and then entered the chamber as if prospecting for a new nest site. This bird was less than half the size of a cahow, with a different vocal pattern, so we knew it was something new. He spent about an hour rummaging around and then departed before sunrise, leaving all of us who were watching online not sure what we had just witnessed and thankful that it had been recorded.”

Chief terrestrial conservation officer Jeremy Madeiros initially believed the bird to be from the storm petrel family, which is of the same nocturnal, burrow nesting tube-nosed family as the cahow. However, none of these is known to have ever landed or nested in Bermuda, let alone be filmed doing so.

“As of 4.30am this morning, ‘Stormy’, as he is now nicknamed, was sitting in the entrance of the recently vacated cahow burrow on the edge of a cliff on Nonsuch Island, calling out to sea for a prospective mate, whilst unknowingly connected to the digital world.”

The Nonsuch Expeditions team digitised the video and the audio recordings and shared the footage among the local and international birding community experts and the consensus so far confirms Mr Madeiros’s suspicion that it is the dark-rumped variation of a Leach’s storm petrel. The birds normally nest 800 to 900 miles away in the Canadian Maritimes and are less than half the size of the cahow, with a wingspan of 19 inches as opposed to that of 36in to 38in for a cahow.

Mr Madeiros added: “We all thought we had witnessed an amazing one-off event. However, the CahowCam has allowed us to witness two more 3.30am visits as this little bird who seems to be intent on occupying this nest and attracting a mate. The odds of this bird not only deciding to nest in Bermuda 800-plus miles from home but also happening to pick the one burrow where we have a camera operating must be a million to one.

“Now that he is here, there is actually the remotest possibility of him succeeding in attracting a mate, as the species is known to feed in our open ocean waters. This is a great gift for today, World Oceans Day, as it shows that even as we increase our understanding, there is so much more to learn.”

The 2016 nesting season has produced record numbers from the Nonsuch Island colonies, with six out of a total ten chicks having fledged, and is on track to produce the second-highest number of fledgelings from the whole colony, with 58. There were 59 in 2014.

• You can log in to www.nonsuchisland.com/live-cahow-cam/ for updates or watch live. To view the video and any subsequent footage, visit www.nonsuchisland.com