Play behaviour may be subdivided into social play, locomotor play and object play. Object play has been proposed to constitute an important factor in developing skills concerned with physical problem solving. Especially tool using species seem to benefit from object play during their ontogeny. However, object play is not easily distinguished from exploration as both behaviours seem to serve no immediate benefit. Here we try to discuss proposed definitional differentiations and their implications. Further, we provide examples of how object play might be adaptive for problem solving proficiency in some bird species, indicating similar ecological factors driving the evolution of object play in primates and birds.