As long as the owl is able to fly, even for a short distance, it should be
left alone. Many owls that are winter visitors from the north are young
males dispersing to find new territory and may well be stressed or
undernourished. This is natural, albeit unpleasant. However, if the bird
has an obvious broken wing, it definitely will not survive unless it is
rehabilitated, and even then, it is doubtful.
As others are sure to mention, winter owls like N. Hawk Owls, Snowy Owls,
and S.E. Owls spend a lot of time on the ground, particularly snowies, who
don't really know what a tree is. Trying to help the owl is likely
stressing it even more. They could throw it a few dead mice, but further
intervention is not advised.
Port Kent, NY