Wikipedia
Kooshdakhaa are mythical shape-shifting creatures found in the stories of the Tlingit and Tsimshian Indians of Southeastern Alaska temperate rainforest. Loosely translated, Kooshdakhaa means, "land otter man".
They are similar to the Nat'ina of the Dan'aina Indians of South Central Alaska, and the Urayuli of the Yup'ik in Western Alaska.
Physically, Kooshdakhaa are shape-shifters capable of assuming human form, the form of an otter and potentially other forms. In some accounts, a Kooshdakhaa is able to assume the form of any species of otter; in others, only one. Accounts of their behaviour seem to conflict with one another. In some stories, Kooshdakhaa are cruel creatures who take delight in tricking poor Tlingit sailors to their deaths. In others, they are friendly and helpful, frequently saving the lost from death by freezing. In many stories, the Kooshdakhaa save the lost individual by distracting them with curiously otter-like illusions of their family and friends as they transform their subject into a fellow Kooshdakhaa, thus allowing him to survive in the cold. Naturally, this is counted a mixed blessing. However, Kooshdakhaa legends are not always pleasant. In some legends it is said the Kooshdakhaa will imitate the cries of a baby or the screams of a woman to lure victims to the river. Once there, the Kooshdakhaa either kills the person and tears them to shreds or will turn them into another Kooshdakhaa.
Legends have it Kooshdakhaa can be warded off through copper, urine, and in some stories fire.
Since the Kooshdakhaa mainly preys on small children, it has been thought by some that it was used by Tlingit mothers to keep their children from wandering close to the ocean by themselves.
It is also said that the Kooshdakhaa emit a high pitched, three part whistle in the pattern of low-high-low.