Ground-hornbills (Bucorvus) show means-end understanding in a horizontal two-string discrimination task

Abstract

This study investigates problem solving in one northern ground hornbill (Bucorvus abyssinicus) and two southern ground-hornbills (Bucorvus leadbeateri) in a horizontal string-pulling task. In five conditions, two strings were stretched out on the ground and subjects had to pull the end of the string which was properly connected to an out-of-reach food reward. Two subjects succeeded above chance in choosing a rewarded string over an unrewarded one (parallel and converged conditions), and continued pulling longer strings when the reward did not immediately move closer (coiled condition). One bird additionally understood which string was physically connected to the reward (contact condition). Although this study is preliminary, it highlights the necessity to extend research on physical cognition to other large-brained avian orders in order to better understand the underlying ecological and social selection pressures involved.