“As the 2025 Cahow nesting season has been finished for about 3 weeks, with the last of this season's chicks fledging out to sea between the 13th and 21st June, it is a good time to review some of the details about the recovery program for Bermuda's unique, and endangered, National Bird.
We had a total of 78 successfully fledging chicks this year, the second highest on record, only exceeded by 79 chicks in 2021.
The Cahow, or Bermuda petrel (Pterodroma cahow), once superabundant across the Bermuda Islands, was quickly decimated by the arrival of humans on the islands, and in particular by the introduction by the settlers of mammal predators such as hogs, rats (accidently), cats and dogs, to the point where it was considered to be extinct by the 1620s.
This belief persisted until 1951, when just 18 breeding pairs of Cahows were miraculously re-discovered on 4 tiny half-acre, small rocky islets, which were so small and difficult to land on that their presence went undiscovered for 330 years. Dr, David Wingate managed the species for 40 years, controlling rats and building artificial burrows, enabling the population to increase to 53 pairs by the time he retired in 2000. In the 25 years that I have managed the project, I have continued this work, with the population tripling to its present level of 165 established breeding pairs,
By 2009, I was able to get two new breeding colonies established on the much larger and more elevated Nonsuch Island, which is much more resistant to hurricane flooding and sea-level rise, through the translocation of near-fledged chicks from the original small islets to artificial burrows on Nonsuch. This involved two 5-year projects, with a total of 175 chicks moved to Nonsuch and fed daily on fresh Anchovies and Squid for up to 3 weeks, enabling them to imprint on their new home before fledging out to sea. Three to six years after fledging, almost half of these birds returned as adults, with the first returned birds producing the first naturally hatched Cahow chicks on Nonsuch since the 1620s.
These colonies have in the last 16 years grown to 40 breeding pairs, and Nonsuch has been assessed as being eventually capable of supporting up to 5,000 pairs of Cahows! I certainly won't live to see those numbers, but as a biologist it has been deeply satisfying to get the recovery on Nonsuch rolling, so to speak!”
Jeremy Madeiros | Chief Terrestrial Conservation Officer > Department of the Environment and Natural Resources