Williamson’s lovingly accurate study of otters includes many examples of the playfulness of these animals, be it with each other, with other species, with water, or with inanimate objects.  I liked the contented croaks of the jackdaws as they stretch wings and seek fleas.

‘They played for a while, but jackdaws were beginning to talk in soft, deep, raven-like croaks in the wood, as they wakened and stretched wings and sought fleas.’

Source: Henry Williamson, Tarka the Otter: His joyful water-life and death in the two rivers, illus. C.F. Tunnicliffe (Harmondsworth: Puffin Books, 1976 (1927)), p. 20