Use of appeasement display and recruitment by an adult Striated Caracara (Phalcoboenus australis) to overcome territorial defense

Abstract

Adult animals across many taxa use appeasement signaling to minimize or avoid costly conflict in social settings by jointly communicating their consent to defer and an interest to remain. When foraging, however, appeasement may not be enough to gain access to a resource controlled by a dominant conspecific. In this case, conspecific recruitment can shift the social dynamic, so the resource becomes accessible to all. Striated Caracara (Phalcoboenus australis) are Near Threatened scavenging falconids that breed in high densities on the extreme southern coasts of South America and the Falkland Islands. While juvenile caracaras recruit other caracaras to concentrated food resources, neither recruitment nor appeasement has been reported in adults. Here we describe a female adult caracara that appeared to use both appeasement signaling and recruitment to access food in another pair's defended territory on New Island, Falkland Islands. Appeasement and recruitment calls are one of several behavioral parallels that researchers have noted among Striated Caracara, Common Raven (Corvus corax), and Kea (Nestor notabilis). Although falconids are not typically considered in comparative studies of avian cognition and social behavior, we suggest that caracaras merit further attention, especially given their relationship to parrots in the clade Eufalconimorphae.