Development of object permanence in food-storing magpies (Pica pica)

The development of object permanence was investigated in black-billed magpi es (Pica pica), a food-storing passerine bird The authors tested the hypoth esis that food-storing development should be correlated with object-permane nce development and that specific stages of object permanence should be ach ieved before magpies become independent As predicted, Piagetian Stages 4 an d 5 were reached before independence was achieved, and the ability to repre sent a fully hidden object (Piagetian Stage 4) emerged by the age when magp ies begin to retrieve food. Contrary to psittacine birds and humans, but as in dogs and cats, no "A-not-B error" occurred. Although magpies also maste red 5 of 6 invisible displacement tasks, evidence of Piagetian Stage 6 comp etence was ambiguous.