In truth, it is the vast oceans of the world that are home to myriad species of sea birds, but just where do they head when they leave terra firma behind them?

Bermuda's own cahow is a petrel species for whom that question has remained a mystery, and one that has been largely unanswered in the half-century since their rediscovery.

This information can be critical to the survival of a species, and particularly to rare ones such as the cahow. Man may unknowingly endanger their favoured habitats – mounting oil platforms and some fishing practices are harmful to some species – thus threatening their chances of long-term survival.

Australian petrel expert Nicholas Carlile, who brought his expertise to the cahow relocation project in the aftermath of Hurricane Fabian in 2003, is back in Bermuda, and he has brought with him the tools to help answer that question.

Mr. Carlile has been involved in seabird and island research for 20 years with the Department of Environment and Climate Change in New South Wales in Australia.

During his three-week visit here, he and Conservation Officer Jeremy Madeiros are fixing pea-sized data loggers to 12 cahows.

The loggers were purchased with money donated to the project from all sections of the community.

"Saltus Cavendish went above and beyond and donated enough money raised at their 'Rockin Robins Christmas Sing-along' for two of the loggers," said Mr. Madeiros.

This tiny and sophisticated piece of equipment collects location information and stores it while the bird is at sea.

Upon the bird's return the data is down-loaded and tells scientists in general terms where the birds travel when they leave their burrows.

Currently it is believed that cahows fly as far as the US east coast off the Carolinas and as far north as Newfoundland, but nobody knows for sure. Now, using this archival-tag technology, the mystery looks set to be unravelled.

Mr. Carlile, who has already given a talk on the extremely rare Fiji petrel while he been here, has worked with many species of birds and extensively with the Providence Petrel, which has many similarities to our own cahow.

Like the gadfly petrel, this seabird has a limited nesting area. Lord Howe Island in the South Pacific is home to most of the population of this species.

As well, the data loggers have already been used to determine the at-sea movements of the Providence Petrel.

Mr. Carlile will be talking about his work with the Providence Petrel and highlighting its parallels with its cousin the cahow tonight at 7 p.m. at the BUEI Tradewinds Auditorium for the Bermuda Audubon Society.

Admission is $15 for members and $20 for non-members while children are $5. Tickets are available at the door.