Sweet Hunters (1970)

An ornithologist goes on a field trip to a deserted island near the mainland with his wife and small son, and is joined by the wife's sister, who is getting over an abortion; later, an escaped convict is discovered. A situation which may seem naturalistic enough, but the form never is: incidents are isolated, cross-relations are oblique, emotions are unexplained.

Unfortunately the movie Sweet Hunters is not yet available on HBO Max.