 Heaney, Gray, and Taylor concluded that these results put keas on a par with elephants and chimpanzees in terms of cooperative pulling.These conclusions are in sharp contrast to those of Schwing, Jocteur, Wein, Noë, and Massen, who tested ten captive keas in a loose-string task on an apparatus that provided limited visibility to follow the trajectory of the string.After training with a human partner (no solo training was done), only 19% of trials led to the birds obtaining food in the joint task.