What Am I?

❄️ 🎄 ❄️ It’s What Animal am I Wednesday?
I am native to the arctic to sub-arctic regions of the Northern Hemisphere. I stand about 1.2 meters tall, not including my antlers. I am covered in thick brown or dark grey fur which keeps me nice and warm in the freezing landscape. I like to eat grasses and occasionally root vegetables if someone else pulls them up and leaves them out for me.
I have several unique evolutionary adaptations which some people describe as a bit “magical”. I have a bioluminescent naval cavity which enables me to navigate through thick snow or fog. A by-product of digesting vegetables is hydrogen gas, which is very light and allows me to escape predators by making me almost weightless – I can practically fly through the air! I am most active around the winter equinox, which typically occurs in late December.
Who do you think I am?
📷 Jon Tyson on Unsplash (cropped)