I think it was German from the 80s or 90s and the only scene i remember from it was the two girls stripping down to their underwear in the woods and playing with a dead bird or rabbit.
These are the films i know it is not: Maladolescenza, The Crucible, Heavenly Creatures.
Quite possibly Kissed (http://www.imdb.com/title/tt0116783/).
It's a Canadian film, but it does feature a scene where the main character tries to enlist her friend in a necrophiliac ritual. It involves a dead small animal.
The rest of the film moves on from that, but I think it may be the movie you're thinking of.
I just downloaded this and you're right, it's the one. :cheers:
Great!
I did like the movie, to an extent. Glad we could find it for you.