Flehmen response

The Fallow Deer rut is in its early stages - it generally starts a little later than the Red Deer rut. The Fallow Buck seen here is displaying the Flehmen Response. By curling up his top lip he exposes an organ in the roof of his mouth that can detect pheremones and other scents that indicate when a Fallow Doe is in season. This behaviour is found in horses, Red Deer and several other species of animals.
Here endeth the biology lesson!