Juan Fernández petrel (Pterodroma externa)
|Spanish:||Peterel de las Juan Fernádez|
|Size||Length: 43 cm (2)|
Wingspan: 95 – 97 cm (2)
|Weight||500 g (2)|
Classified as Vulnerable (VU) on the IUCN Red List 2007 (1)
Petrels are oceanic birds, with broad webbed feet suited to their aquatic lifestyle, and long wings that enable them to fly great distances over the ocean and endure mighty storms. The plumage of the Juan Fernández petrel is brownish-grey on the back, with a black M-shaped marking across the extended wings. The underparts are white, with the underside of the wing edged in black. The face is white, with a black ‘cap’ extending to below the eyes (2) (3). The black bill has a hooked tip and houses the tubular nostrils that are a unique feature of the Procellariiformes, also known as the ‘tubenoses’ (4).
The Juan Fernández petrel breeds only on Alejandro Selkirk Island, part of the Juan Fernández Islands, Chile (2). When not breeding it can be found over the tropical and subtropical waters of the east Pacific; north to Hawaii, and as far east as New Zealand and eastern Australia (2)
The Juan Fernández petrel is a marine and highly pelagic species that is often found in areas of upwelling, and rarely approaches land except to breed. It breeds on slopes and ridges in fern, forest or grassland, on high ground, between 600 and 1,000 meters, (2).
Juan Fernández petrels spend most of their life out over the oceans, where they search for fish and squid on which to feed (2). They are often found in areas of upwelling, where cool, nutrient-rich water rises to the surface, resulting in an abundance of prey. They can be seen feeding alongside other seabirds (2), or occasionally around fishing boats (2). The Juan Fernández petrel often depends on sub-surface predators, such as cetaceans and yellowfin tuna, to drive prey to the surface (3).
Juan Fernández petrels return to their isolated island to breed in October to November (2), where they form large breeding colonies. Females lay a single egg in a burrow and the grey, downy chicks hatch in February and March. The chicks are brooded for typically three weeks before being left unattended during the day while their parents go off to feed (2) (5). The adults return by dusk to their burrows and waiting offspring. Most of the petrel chicks fledge in May and June (2).
The Juan Fernández petrel appears to face its greatest threats on its tiny breeding island, where numerous introduced species are causing extensive damage to the natural ecosystem, and potentially impacting petrel numbers. Introduced rats, feral cats and coatis pose a significant threat to the Juan Fernández petrel through predation; rabbits compete for burrows; and cattle trample burrows and may degrade suitable breeding habitat through grazing (2) (3) (5). The Juan Fernández petrel may also be affected by human disturbance on their breeding grounds, and fisheries may be indirectly affecting the petrel by reducing numbers of sub-surface predators, such as the yellowfin tuna (3).
Since 1935, the Juan Fernández Islands have been designated a national park and in 1977 they were declared a biosphere reserve (3). However, these measures have offered no protection against the abundant introduced predators that are impacting the island’s native inhabitants. There have been attempts to control these invasive species; in 1983 sheep were successfully removed from Alejandro Selkirk Island (3), and the Juan Fernández-Dutch Cooperative Project implemented control programs for several exotic plant species, goats, and rabbits (5). The Juan Fernández Islands Conservancy (JFIC) aims to protect the long term health of archipelago through a combination of basic research, applied conservation and environmental education in collaboration with local residents (5). In 2001, JFIC began a research program focused on four pelagic seabirds, including the petrel, investigating their basic ecology and factors potentially important for future conservation measures (5). However, without eliminating the threats posed by invasive species, any other conservation measure is likely to be fruitless, and thus JFIC believes that complete eradication efforts, (as opposed to control programs), are necessary (5). Improving management of yellowfin tuna fisheries to ensure their sustainability is also likely to benefit the Juan Fernández petrel (3).
For further information on the Juan Fernández petrel see:
Juan Fernández Islands Conservancy:
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- Cetaceans: a group comprising all whales, dolphins and porpoises.
- Nocturnal: active at night.
- Pelagic: inhabiting the open oceans.
IUCN Red List (October, 2007)
- del Hoyo, J., Elliott, A. and Sargatal, J. (1992) Handbook of the Birds of the World. Vol. 1: Ostrich to Ducks. Lynx Edicions, Barcelona.
BirdLife International (October, 2007)
- Burnie, D. (2001) Animal. Dorling Kindersley, London.
- Juan Fernández Islands Conservancy. (2003) Biology and Conservation of the Juan Fernández Archipelago Seabird Community. 2003 Season Report. Juan Fernández Islands Conservancy, Washington.