This photo demonstrates the action called "flehming". We were near the timing of the Bighorn rut in Alberta and this ram was checking scent. The open mouth and curled lip enhances the reception of scent, and the behavior is especially seen during rut.
I love to hunt with a gun but it is remarkable how much more immersed in wildlife behavior one becomes when out with just a camera.
This shot benefits from the dark shadowed background which makes the subject pop. Images work best when the subject is evenly lit by the sun. The human eye has much more "dynamic range" than a camera. This enables us to easily see detail in heavy shadow. But when you view a photo taken where the subject is in uneven, shadowed light much important detail is lost.
I could have shot at a slower shutter speed in order to increase depth of focus with a higher f-stop. But the subject is parallel to the plane of focus already and f8 is sufficient for depth of focus without allowing distracting detail to appear in the background with a higher f-stop.
Nikon D1X camera
80-200mm VR lens at 200mm
1/400 sec at F8