John,
I normally don't use the saturation slider in lightroom at all. But I would suggest that you try increasing the colour temp and the saturation and increase the black a bit. This I feel is a must as the image near the bottom of the bison is a bit light. I would also take off a little bit from the bottom without reducing any other side. I feel this image has lot of potential still to be exploited. Like it.
Cheers,
Sabyasachi
I think Sabyasachi has a good suggestion on the silhouette. I downloaded and tried a curves adjustment locking the curve at the mid point and 3/4 point and then darkening the shadows by placing a point at the 1/4 tones and pulling down. Made all the shadows darker and created a nice looking graphic quality to the image.