Cahows are facing a “potentially devastating threat” from the passage of Hurricane Melissa, Nonsuch Expeditions has reported.

JP Rouja, the organisation’s founder and a team leader, said that cahows have been returning to the island in St George’s early in recent years, bringing them during the hurricane season — a trend believed to be triggered by climate change.

He said while there is little concern about the safety of the birds on elevated Nonsuch Island in St George’s, neighbouring nesting islands may face a challenge.

Observers will be able to watch the cahows in their burrows via Cahow Cams — the cameras operated by Nonsuch Expeditions, which are located the birds’ burrows and on the island’s surface.

Mr Rouja said: “Whilst not as much of a concern for the Nonsuch Island colonies that were built more than 50ft above sea level for this very reason, some of the burrows on the original nesting islands get completely over swept during hurricanes and are under major threat not only from physical damage to the concrete burrows … but even more worryingly when early returning birds overlap with late season hurricanes as we look to be facing later this week.”

He added: “After a rather frustrating late summer to early fall, Bermuda has felt the effects of three near-miss hurricanes with Erin, Humberto and Imelda, but fortunately none of the cahows were back yet.

“However now, as the decreasing yet still threatening Hurricane Melissa lines up to pass Bermuda on Thursday night as a Category 2, even if it keeps its current track passing to the west, the accompanying swells are predicted as of this writing to be as high as 35ft feet.

“These, depending upon their direction, could completely over sweep the Green Island and Long Rock colonies which would be a disaster, as many of the pairs on those islands will be back and hunkered down in their nests.

“We can only hope that Melissa's path to the west of Bermuda will reduce the size of its accompanying swells and surge, which generally are larger if a storm passes to the east or southeast of the island.

“All we can do is hope for the best and assess the damage on the smaller original nesting islands once the hurricane, hopefully the last of this season, is past the island and conditions calm enough to get back out in the boat.”

Footage of the Cahow Cam 3 surface camera during the storm will focus on Green Island to monitor the conditions during daylight hours.

• Visitwww.nonsuchisland.com/live-cahow-camfor updates and footage