Anecdotal accounts about animals repeatedly exposing themselves to sources of passive movement by engaging with swings, slides, or carousels are generally assumed to be "play." Criteria for play-like behavior require the activity to be (1) of no immediate relevance for survival
(2) voluntary, intentional, and rewarding
(3) non-ethotypical
(4) repeated, yet unstereotyped
and (5) free from stress.