Bermuda Petrel (Pterodroma cahow)

Bermuda Petrel

Subspecies

Genus	Species	subspecies	Region	Range
Pterodroma	cahow		AO	wc

Genus

Genus Pterodroma, Pseudobulweria and Aphrodroma are also knwon as the Gadfly Petrels. They vary in size from rather small birds such as the Cookilaria-species, measuring about 26 cm, to the much larger and robust representatives of this group like the White-headed Petrel with an overall length of about 43 cm. Their plumages also vary a great deal from species to species; from completely black to light grey mantles and pure white bellies, and with different color phases within species. One feature shared by all of them is the black bill of which the shape also shows much variation. Some species are extremely rare and restricted to a very limited area, other are abundant and wander widely or have unknown pelagic ranges.
The group of the Gadfly Petrels counts over 35 species, mainly from the Southern Hemisphere. There are three genera: Pterodroma with about 30 species, Pseudobulweria counting four and Aphrodroma with only one. Many authors have tried to classify the large number of species of this group and to determine their relationships. This has resulted in a division in several subgenera and the grouping of several species which are considered to have a more or less close relationship. The taxonomic discussion has not come to an end yet: new species have been added or split recently and probably will be in the near future.

Physical charateristics

Medium-sized, long-winged, brownish-grey and white gadfly petrel. Brownish-black cap extending to eye, but interrupted by pale eyebrow. Brownish nape extending towards upper breast to form partial collar. Brownish-grey mantle, upperwing and tail. Pale uppertail-coverts may form narrow whitish band. Entirely white underparts. White underwing with narrow black trailing edge, black tip, extending narrowly onto leading edge. Black bill. Pink legs, pink feet proximally, black distally.

Listen to the sound of Bermuda Petrel

[audio:https://planetofbirds.com/MASTER/PROCELLARIIFORMES/Procellariidae/sounds/Bermuda Petrel.mp3]

Copyright remark: Most sounds derived from xeno-canto

wingspan min.:	87	cm	wingspan max.:	91	cm
size min.:	36	cm	size max.:	39	cm
incubation min.:	51	days	incubation max.:	54	days
fledging min.:	90	days	fledging max.:	100	days
broods:	1		eggs min.:	1
			eggs max.:	1

Range

Atlantic Ocean : Westcentral. Pterodroma cahow once bred abundantly throughout Bermuda (to UK).

Habitat

It formerly nested in soil burrows, but such habitat is not available on current breeding islands and it now nests in suboptimal, natural erosion limestone crevices and artificial burrows.

Reproduction

The breeding season is January-June, and breeding success has increased from less than 5% per year in the 1950s to more than 25% per year in the 1990s. Ringing recoveries have shown that birds return to birds first return to breed four years after fledging. The breeding grounds are not visited by birds between mid-June and mid-October

Feeding habits

Little known. Probably crustanceans, fish and squid.

Video Bermuda Petrel

httpv://www.youtube.com/watch?v=ZI4DARxZw4I

Conservation

Successful conservation has increased the population of this species, but it remains extremely small and the species consequently qualifies as Endangered. If the population continues to grow, which recent figures suggest it has, the species will warrant downlisting to Vulnerable in due course.
Pterodroma cahow once bred abundantly throughout Bermuda (to UK). It was thought extinct for almost three centuries, until reported (with specimens) during the first half of the 20th century. In 1951, 18 pairs were rediscovered breeding on suboptimal rocky islets (total area 1 ha) in Castle Harbour. Intensive management has resulted in slow but steady increases, and the population was estimated at 250 birds in 2005, with 70 pairs fledging a record 40 young in 2003, and 71 pairs fledging 35 young in 2005. More recently, 40 young fledged in 2008 and at least 35 chicks hatched in 2009. Fourteen individuals fledging from Nonsuch Island after translocation in 2005 and 2006 were observed in 2009 returning to the island and entering artificial burrows. One chick was born on the island in 2009.

Migration

In the non-breeding season, birds probably move north into the Atlantic, following the warm waters on the western edges of the Gulf Stream2. There are confirmed records off the coast of North Carolina, USA1,3, and one bird was captured in the Azores in November 2002. Probably follows the Gulf Stream.

Distribution map

Bermuda Petrel distribution range map

Planet of Birds