Much better on the left tree, was gonna say there shouldn't be a highlight on the right edge. I like how the darkness creates a feeling of space in the composition.
I'd darken the sky color, make it bolder and bluer maybe. It's so bright outside in the real world, that it's surprising how deep the sky blue can be.
Hollows aren't so frequent, it'd be a rare occurrence to have two trees with hollow next to each other. Feels contrived, but maybe that's just me.
I think it would make a better frame if on the left tree you raised the branch to show more of the center, and filled in the top left sky with leaves.
Just some ideas.