I'd like to ask for your help again. I can't remember (nor find) the title of a Western film I saw in the 1980's, about some settlers finding the remains of another wagon train that had recently been slaughtered. There were only two (possibly one?) survivors: adolescent girls. They join the wagon train of their saviors, trying to cross a treacherous mountain pass. The settlers are killed one-by-one, and in the end the young girls turn out to be the murderers (in the final scene we find out they can communicate with eagles).

Thank you in advance,