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Bermuda Petrel Pterodroma cahow

Bermuda Petrel

At a glance

Breeds only in Bermuda

Once thought to be extinct

Survives only because of careful management by conservation officers in Bermuda

The rarest extant seabird in this hemisphere

The very existence of this species is the result of the dedicated work of one individual: David Wingate


Bermuda petrels were first discovered in Bermuda in the 16th century when nesting birds numbered in the hundreds of thousands. They do not nest at any other locality, and they went extinct at all known, mainland localities by 1620 as a result of human exploitation and introduced predators including wild pigs. After being considered extinct for over 300 years, 18 pairs were discovered in 1951 on five small islets off Bermuda.



Small petrel (15 inches, 38 cm, in total length). Resembles the larger Black-capped petrel but lacks white collar and rump patch. Less white in forehead region. Short massive black bill with tube-nose. Black-capped Petrels have a darker form that has restricted amounts of white on dorsal surface and could cause confusion with identification. No sexual differences in morphology.


Like the adults.


The North Atlantic may have been colonized twice by Pterodroma, once by summer breeding species, and once by winter breeding ones (P. hasitata, P. cahow).  Several authors have stated that the Bermuda Petrel P. cahow is a form of P. hasitata.  Helicoidal twist counts of intestines indicate that the Black-capped Petrel and the Bermuda Petrel are clearly distinct and that the Bermuda Petrel may be of closer affiliation to the European petrels of the eastern North Atlantic.

Likely locations

Bermuda, Gulf Stream off of the Carolinas.

Alternative common names

Bermuda: Cahow (named after loud nocturnal vocalization)


Endemic: Breeding confined to small islets off of Nonsuch Island, Bermuda. At sea distribution poorly known. Other than birds seen around Bermuda and off SE United States there are several unpublished reports from the Sargasso Sea. Like others in the genus Pterdroma, this petrel most likely disperses great distances from their breeding site.



At sea

The only published records of at sea occurrence are for waters around Bermuda and from the Gulf Stream over the Outer Continental Shelf of North Carolina. Thus, the latter appears to be an important foraging area for this rare species. Unpublished reports of individuals in Sargasso Sea. Found off North Carolina April to August, with one December report.

At the nest

Their current total nesting range is less than one hectare. Winter breeder, nesting in burrows under rocks. At breeding sites from late October through May. Nocturnal. Single white egg. Pairs reuse same nest site from year to year.

Current Population

32 pairs in 1984, increasing to 53 pairs by 1999. This is one of the most endangered birds in the world. Hurricanes in the last decade have destroyed a number of their nesting burrows and the population is currently lower than the 1999 count of 53 pairs. Bermuda reported 29 pairs actively nesting in 2005.

Conservation Status

Endangered US Fish and Wildlife Service (Federal Register 8495) but just recently recognized as occurring in US waters due to the previous lack of documentation(specimens/photos). Nesting population is carefully managed by Bermuda government.

Conservation Needs

The Bermuda government is vigorously protecting the islets on which these petrels nest. The sites are constantly monitored for rats, and additional nest sites are constructed as the population expands. Natural nest cavities have been fitted with excluder baffles to prevent tropicbirds from evicting petrel eggs and chicks. Nest are repaired and cleaned of sand and debris after major storms. Feral cats on Bermuda would seemingly prevent recolonization of the mainland by this species.

Playback of vocalizations could be used to attract first year breeding birds to new nesting sites. An abandoned US military base could be used as a site for expanding the existing limited nesting areas used by this species. Because of the high profile of this globally endangered species, carefully thought out ecotourism focused on this petrel could help raise funds for stepping up the species' recovery rate.

Concerns continue that offshore oil exploration could harm birds at known foraging areas off the Southeastern United States. Oil spills, the release of heavy metals into the water column through drilling operations, and lights associated with drilling platforms would all prove detrimental to the species survival.



External images and videos

Selected References

Lee,D. S. 1999. Pelagic seabirds and the proposed exploration for fossil fuels off North Carolina: a test for conservation efforts of a vulnerable international resource. Jour. Elisha Mitchell Scientific Soc. 115(4): 294-315.

van Halewyn, R. and R. Norton. 1984.The status and conservation of seabirds in the Caribbean. Pp. 169-222. In J. P. Croxall, P. G. Evans and R. W. Schreiber (eds). Status and Conservation of the World’s Seabirds. ICBP Tech. Publ., No. 2. 778 p.

Wingate, D. 1968. DDT Residues and Declining Reproduction in the Bermuda Petrel. Science 159(3818): 979-981.

Wingate, D. 1972. First successful handrearing of an abandoned Bermuda Petrel Chick. Ibis 114(1): 97-101. 


David Wingate, Jeremy Madeiros

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West Indian Breeding Seabird Atlas
by Will Mackin and David Lee is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 United States License. Based on work at www.wicbirds.net.Permissions beyond the scope of this license may be available at www.wicbirds.net.

Suggested citation: Lee, D. S., W. A. Mackin. 2008. Bermuda Petrel. West Indian Breeding Seabird Atlas <http://www.wicbirds.net/bope.html>. Last Updated: _____. Date accessed: ______.

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