Yup, you got it now. Most owls are solitary and territorial animals. As predators, their food supply is often limited, so they don't like sharing. Any other owl is just competition for limited resources, so even in a place that looks infinitely spacious to us, it's too close in this most likely female Snowy Owl's opinion.

Oh, Tamriel.

Good eye, sniper! I suppose it's possible the artist was just painting off the cuff, but your photo is a very compelling argument for their inspiration.