News on the Cahow

The most recent Cahow nesting season began in mid-October 2005 and ended with the successful departure of the last chicks from the nesting grounds on Nonsuch and other Castle Harbour Islands on the night of 17th June, 2006. 5 new nest burrows were occupied by new pairs of Cahows, raising the total number of active Cahow nest burrows to a new record high number of 75. The original number of Cahow nesting pairs remaining when the Cahow was rediscovered was only 17 to 18, so this represents a more than four-fold increase in the breeding population. Despite this, the Cahow continues to be one of the rarest seabirds on Earth and is listed as critically endangered.

The total number of Cahow chicks fledging successfully in 2006 rose to 36, up from 35 in 2005 and 29 in 2004. Of these, 20 were translocated to Nonsuch Island as part of the translocation project to establish a new nesting colony which is much safer from flooding and erosiion from hurricane and storm waves than the present tiny islets that the Cahow is confined to. Some of these islets suffered from partial collapse during hurricane 'Fabian' in 2003. This follows on from 21 chicks successfully moved in 2005 and 14 moved in 2004. Therefore, a total of 55 Cahow chicks have already flown out to sea from nonsuch Island out of a planned total of 95 chicks over a five-year period. It is planned to move another 20 chicks a year in 2007 and 2008 to complete the project, and by 2008 it is hoped that the first Cahow chicks should begin to return as adults, hopefully to establish their own nest burrows, raise their own chicks and bring the project full circle.

Not only is Nonsuch island higher and larger than the present nesting sites,but it is also covered by thick soil and forest cover, which should enable the Cahows to be able to dig their own burrows. At present, Cahows can only use deep natural rock crevices, of which only a few are suitable on each island, or artificial concrete burrows made on the islands by the terrestrial conservation division of the Dept. of Conservation Services.

The other exciting event to happen in 2006 was the first return of Cahows banded in 2002 and 2003 as chicks in nest burrows on the present nesting islets, back to the islets as adults after several years of living on the open ocean, generally hundreds of miles from any land. Prior to 2002, Cahows had not been fitted with identification bands and there was no way to tell individual birds apart. It was thought that Cahow chicks required at least 5 to 8 years before they were old enough to breed, but we now know as a result of these returns that at least some of the birds can return as early as 3 years of age, with most returning at 4 years. 9 chicks have now been confirmed as returning, 7 from 2002 and 2 from 2003. 6 of these returned to the same island they were hatched on, and 3 went to other islands. We also know a bit more about just how many of the chicks survive those first several years at sea, when they are learning how to survive. 25% of the chicks banded in 2002 have now returned after surviving a very difficult teacher...the North Atlantic Ocean! it is amazing that even this many survive to this point, as there is no supervision from the adults, the chicks are thought to be totally on their own, and they have to learn how to find and catch food and survive predators and storms completely on their own instincts and amazing flying abilities. A very humbling fact and testimony to the strong will to survive of Bermuda's national bird.

In the next couple of years new techniques planned include fitting some adult Cahows with data loggers which can record the locations of the birds at sea over long periods, to finally begin to solve the mystery of where the birds go when they leave Bermuda.

As we begin a new nesting season, I will keep you informed of further progress and developments with the Cahow Recovery Project.