Hi Sid - I've looked at this for a while and I really like the backlighting and the yellow glow but I feel like the tree is too dominant. It makes the bison seem cramped in the frame and so I find myself wanting more room for the bison to the left. Perhaps moving to the left in the field if possible would have lessened the feeling. Of course, quite probably it is just me and others will disagree.
I first viewed the image with the top cropped off and I think it becomes much stronger so presented. Otherwise I like the composition and colours, I would consider sharpening the bison a bit more.
Sid, I do like this one. A small suggestion, how about crop from the bottom, to just above the branch in the snow. This moves the bison down some, gets rid of the distracting branch, and I feel makes the tree less dominant and pulls your eye to the bison while not distracting from what the tree adds to the frame.
Your image resembles a postcard and I absolutely love the golden light and composition, I just feel the bison itself is a tad too soft in comparison with the tree. A tad more space below would improve this, IMHO. A very special sighting and I thank you for sharing:)
Hey Sid - humbled to be of inspiration to you
Love the light and overall scene here. My first thought was also to crop from the top, but I like what Grady did too.
I'd deepen the overall midtones and contrast a bit?