Striated caracara

The striated caracara (Phalcoboenus australis) is a bird of prey of the family Falconidae. In the Falkland Islands, it is known as the Johnny rook, probably named after the Johnny penguin (gentoo penguin).[2]

Striated caracara
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Aves
Order: Falconiformes
Family: Falconidae
Genus: Phalcoboenus
Species:
P. australis
Binomial name
Phalcoboenus australis
(Gmelin, 1788)

Description

The adults' plumage is almost black in color, while the legs and lores are orange and the neck has silver striations. Chicks have chestnut down, which they lose after their first molt. Juveniles (i.e., after fledging until entering fourth year) have brown plumage with chestnut striations on nape and breast that deepen as they age. Full adult plumage is acquired after the fifth molt (i.e., entering fourth year), though the beak does not reach full adult coloration until the fifth year.

Distribution and habitat

The species breeds on coastal islands off Tierra del Fuego, through the Chilean fjords, and the outer islands of the Falklands archipelago. Although logistical challenges prohibit a comprehensive survey of the mainland population, the Falklands is thought to be the species stronghold. Historical records indicate the species range may have included East Falkland, however striated caracaras now breed only in the outer islands in association with penguin and albatross colonies.

Behaviour

Feeding

The striated caracara is primarily a scavenger, feeding on carrion, mainly dead seabirds and dead sheep, offal and food scraps. Invertebrates also comprise a large part of their diet, including kelp fly larvae dug from intertidal kelp wrack, beetles, and earthworms dug from invasive grasses in hillside drainages. However, striated caracaras will opportunistically prey on weak or injured animals, such young seabirds and newborn lambs, the latter which has led it to be persecuted by sheep farmers.

Breeding

The nest is built on the ground, tussac stands, or cliff ledges, where the female will lay up to 4 eggs. Their hatching is timed to coincide with the nesting season of seabirds, providing a constant food supply for the chicks. Once chicks have fledged, they disperse and gather into flocks.

Status and conservation

The population in the Falklands is estimated at 500 breeding pairs. Juveniles and adults are almost entirely fearless of humans and treat their approach with indifference. Over time, conflict with the sheep farmers has led to a great reduction in their numbers. This is now being corrected by the Falkland Islanders.

  • Subadult striated caracara feeding on a dead gentoo penguin chick
  • Juvenile (2 year old) striated caracara
  • Subadult striated caracara at Amazona Zoo, Norfolk, England
  • Adult striated caracaras on Sea Lion Island, Falkland Islands

References
  1. BirdLife International (2012). "Phalcoboenus australis". IUCN Red List of Threatened Species. 2012. Retrieved 26 November 2013.CS1 maint: ref=harv (link)
  2. Gorman, James (1990). The Total Penguin. Prentice Hall. p. 87. ISBN 978-0-13-925041-5. Sealers called it the "Johnny penguin" or "John penguin." In that incarnation, it seems to have given its name to the striated caracara, a bird of prey that feeds on young gentoo penguins in the Falklands and is called the "Johnny rook."
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