Officials at People for the Ethical Treatment of Animals (Peta) have honoured late actress Misty Upham for her campaign to stop the abuse of bears in captivity.

The August: Osage County star, who suffered from bipolar disorder, was reported missing last week (06Oct14) and confirmed dead after her father identified a body found in a ravine in Auburn, Washington on Thursday (16Oct14).

Upham was a campaigner for the prevention of mistreatment of bears and in January (14), she wrote an open letter to the United States Department of Agriculture calling for a change in the law to protect the animals in captivity.

The actress called the abuse of bears "horrific" and insisted she had a "deep concern for the welfare of all living beings".

Peta's founder, Ingrid E. Newkirk, has now paid tribute to Upham in a statement released to Wenn.

It reads, "The world will be a colder place without Misty's warm heart, and she will be sorely missed at Peta. She was extremely kind and cared deeply about animals; constantly calling for protection for the bears suffering in roadside zoos on tribal land, a call we will carry forward in her honour. It's a tragedy whenever anyone dies before their time, but Misty Upham was a friend to us and to animals everywhere."

Officials at the King County Coroner's Office in Washington are due to make an announcement about Upham's case on Friday (17Oct14). A cause of death has not yet been revealed.