Williamson, who was born in London and had moved to Georgeham, Devon, in 1921, began making notes for "Tarka" about two years later: although he was usually a rather rapid writer, the book took him around four years to write thanks to the large amount of detailed research needed. Williamson often claimed that he was inspired to write "Tarka" after rescuing and raising an otter cub, but the truth of this story is uncertain and it seems likely that the 1909 book "The Life Story of an Otter", by Cornish naturalist John Coulson Tregarthen, was a more substantial influence. Nevertheless, Williamson spent a great deal of time gathering information on otters' habits and behaviour.