Distribution, Nesting Records, and Notes on the Ecology of the White-throated Caracara (Phalcoboenus albogularis)

Abstract

Endemic to Patagonia, the White-throated Caracara (Phalcoboenus albogularis) is one of the least studied caracara species, with several aspects of its ecology, such as breeding biology and diet, largely unexplored. Using citizen science records and opportunistic observations, we obtained data on the breeding biology, nest sites, and diet of the species in Chile and Argentina. Nests were in rocky outcrops and cliffs, and aspects of diet corroborated others’ observations that this species feeds on live prey as well as carrion. The species’ nesting season apparently begins in September and ends in March, with some regional variation. The modal brood size is two, and many nests apparently are used across multiple years. Using citizen science data, we created the first distribution models for the White-throated Caracara, one for the breeding season and one for the winter season. The species predominantly occupies the highland plateaus of western Santa Cruz Province, Argentina, and the Andes Range from around 40° south to southern Tierra del Fuego. The models indicate a mostly consistent distribution without significant latitudinal changes between seasons and, apparently, only a limited transition to lower-elevation areas east of the Andes in winter. In both seasons, this caracara is associated primarily with barren rocky areas and Andean and sub-Andean herbaceous steppe—all open environments—rather than forested areas as has been thought previously. This study provides new knowledge of this regional endemic yet the species remains a poorly known raptor in southern South America. Additional and on-the-ground field research would likely produce benefits when addressing species-related conservation issues.