‘A score of hearts under browny-red coats beat faster at the otter’s chiding yikker as she picked up her cub by the neck and carried him to the shore.’

Repeated short, sharp cries made by a bird or other animal, here applied to otters.  See also ‘yinny’ and ’tiss’.

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. 26