Nildro-hain was a doe that lived in Cowslip's Warren. She was Strawberry's mate, but she died after being caught in a snare. After her death, Strawberry left Cowslip's Warren, to build a new Warren (Watership Down Warren) with Hazel and the other Sandleford Warren survivors. Her name means Song of the Blackbird. After arriving at the Watership Down Warren, Hazel mentions her when discussing their lack of does.
Kingcup is her possible Miniseries counterpart.