Juan Fernandez Petrel

Photo © by Michael Hooper
Coast of Southern Chile, 5 February 2020

Alternative name: Pacific Petrel

Pterodroma externa

Identification

42·5–45 cm (17-18 in) , wingspan 95-97 cm. A large grey and white gadfly petrel, long-billed, dark-capped and with clean white underwings.

• White feathers on forehead with blackish bases (looking as dark spots), pattern extending to anterior superciliary area, plainer white on foreface
• Blackish grey to dark brown-grey cap extending to most of ear-coverts and around eye (sometimes black there)
• Grey or brownish grey rest of upperparts, darker on most of upperwing and tail and with a dark transversal M (like other species of the group)
• Sometimes some spots or even a complete narrow and irregular whitish horseshoe between rump and uppertail-coverts
• Dark grey tips of remiges forming a narrow trailing edge on underwing
• Short blackish-grey and rather narrow crescent starting on carpal angle and not reaching central wing, white rest of carpal area, often with some blackish dots on primary coverts next to anterior edge of wing
• Dark grey exposed undertail with white bases and the outer pair has dark restricted to the distal third or less
• Grey large patch on underparts on side of neck connecting with mantle and forming a partial collar
• Black bill

Sexes similar. Juveniles similar to adults.

Photo © by +Hooper Michael Hooper
at sea between Chile and Peru, 21 March 2023

Similar species

Distinguished from White-necked Petrel by lacking the bold and well-cut white hindcollar, also tends to be slightly darker on uppertail-coverts and tail and less blackish on anterior underwing, especially on carpal area.
About the same size like Galapagos Petrel, but looks generally paler, greyer and more contrastingly patterned above. Also lacks the large blackish patch on carpal area.
Underparts similar like Bermuda Petrel, Barau's Petrel and Black-capped Petrel but easily told from all three species by much whiter underwing and by the latter lacking the broad and clear-cut white horseshoe on rear upperparts.
Similar in plumage to other species (like Masatierra Petrel and Stejneger's Petrel) but note the mostly white underwing and larger size.

Distribution

Breeds on Alejandro Selkirk Island (formerly Más Afuera Island) in Juan Fernandez Islands, Chile.
Migrates north, ranging over tropical and subtropical waters of eastern Pacific, north to Hawaii. Regularly off western Mexico. A Vagrant to New Zealand and eastern Australia.

Taxonomy

This is a monotypic species.
Has been considered a subspecies of Black-capped Petrel and often includes White-necked Petrel.

Habitat

A pelagic species, doesn't approach land except at breeding colonies.
Breeds rather high at 600-1000 m on slopes and ridges in fern forest or grassland.

Behaviour

Diet

Feeds probably mostly on fish and squid. Catches its prey by surface seizing, dipping, aerial pursuit and pattering.
Often associates with other seabirds or cetaceans. Occasionally around fishing boats.

Breeding

Breeding season starts October/November. Nests in burrows, lays 1 egg. Fledging mostly in May/June.

Movements

A transequatorial migrant.

References

1. Clements, J. F., T. S. Schulenberg, M. J. Iliff, S. M. Billerman, T. A. Fredericks, B. L. Sullivan, and C. L. Wood. 2019. The eBird/Clements Checklist of Birds of the World: v2019. Downloaded from http://www.birds.cornell.edu/clementschecklist/download/
2. Del Hoyo, J, A Elliot, and J Sargatal, eds. 1992. Handbook of the Birds of the World. Volume 1: Ostrich to Ducks. Barcelona: Lynx Edicions. ISBN 978-8487334108

• List of references

Recommended Citation

• BirdForum Opus contributors. (2024) Juan Fernandez Petrel. In: BirdForum, the forum for wild birds and birding. Retrieved 5 May 2024 from https://www.birdforum.net/opus/Juan_Fernandez_Petrel

External Links

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