String-pulling behaviour in a Harris's Hawk Parabuteo unicinctus.

Variations on the string-pull experiment have been presented to a variety of avian species. Here, we present the results of a basic vertical string-pull task with a Harris's Hawk Parabuteo unicinctus. A 2-year-old subject retrieved a shielded food reward within 8 min on each of eight trials and spontaneously used solving techniques similar to corvids and parrots. Our data contribute to the small body of literature on raptor cognition by showing that it may be within the realm of at least one bird of prey species to perform the string-pull task similarly to avian species renowned for their high cognitive abilities. [ABSTRACT FROM AUTHOR]