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Raptor Research Center

Autilio, Anna – Striated Caracara (Phalcoboenus australis)

Anna Autilio with a Striated Carcara

Anna Autilio with a Striated Carcara

The Striated Caracara (Phalcoboenus australis) or “Johnny Rook” is a highly social, scavenging raptor native to the Falkland Islands and Tierra del Fuego. The IUCN Near-Threatened status and highly restricted range of this bird have not allowed it to be a subject of intense study, and much is still unknown about their ecology. During the breeding season, Johnny Rooks are reliant on seabird colonies, but during winter when seabirds are scarce, the caracaras must forage differently, which puts different age classes and individuals in conflict, with each other and with the Falklands’ sheep farmers. They can be quite curious and destructive!

Striated Caracara

Striated Caracara

The birds’ tolerance of human proximity and reliance on human settlements as winter foraging grounds makes them an ideal species with which to study carcass consumption over the entire period of a carcass’s availability.  Juvenile caracaras have been observed foraging in groups, and exhibiting “gang” behavior, similar to rooks and ravens, in order to compete with the more aggressive adults. I hypothesize that juvenile vocalization instigates this grouping behavior, and that this behavior is an adaptive strategy for juvenile survival through their first few winters, when raptor mortality is highest. This type of study of social winter feeding dynamics is a tactic chosen by very few solitary raptor species.

My research is conducted on Saunders Island, located in the northwest Falkland Islands. Saunders is the 4th largest island in the Falklands, and though no Johnny Rooks are known to breed there, during the winter groups of 50 or more birds forage in and around the only human settlement on the east side of the island. My goal is to better understand the feeding ecology of this population, in order to reduce the conflict these near threatened birds have with farmers in West Falkland.

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