@Robyn-Hepburn, You mentioned the border you put around the wolves. It does make that part look different from the rest of the illustration. You could try making it a slightly lighter shade than the background behind it, instead of the white. You could also take more space to blend it from light to dark around them.
Also, they look like foxes to me. They are cute.
I'm not sure how realistic you're going for, but you might want to make them larger & stockier for wolves. There are some wolves that look more like coyotes and foxes, but I think they live in warmer climates. Most of the time when people think of wolves, they think of the kind with thicker bodies and necks, and wider, shorter ears and muzzles.
Here's a couple of photos to compare typical / iconic foxes & wolves.
Since the girls are skating on the pond, the wolves would have thick fur like the photo above.
I know foxes can jump & climb into a tree, but I don't think wolves can (at least, not higher than they can jump). I don't think them being in the tree is supposed to be literal here, but it's something to consider.
I don't know this story, but you could also think about what role the wolves take in the story. Are they threatening, fearsome, mysterious, playful, beautiful, curious, or cunning?
The girls kind of remind me of the Charlie Brown kids. 
The foliage in the foreground has a lot of interesting shapes & fanciful design.
Again, I don't know how much realism you want to incorporate into the illustration. If you are going for something more natural & realistic, some of these plants are too tropical.
You could look at a search for cold-hearty evergreen bushes. The palm plant on the lower left & the pointy variegated plant on the lower right definitely look like warm climate plants. The variegated one is very striking, so if you do cut it here, you should save it for another drawing.
I'm not sure about flowers when there's a hard freeze deep enough to make the ice safe to stand on. (I happily live where it doesn't snow.) But some plants can flower in the snow, so if you're going for "close enough" realism, we can say the one in the center is a camellia. You could also have snowdrops or crocus.
The trees in the background would also probably be dormant and leafless, since they look like deciduous trees. The two trees are also very thin to support that much foliage (and animals! 
). The verdant greens add to the liviness of the drawing, so you could change them to evergreens, like pine trees.
Something that is distracting for me is the dark section that goes across the page. I wasn't sure what it was, but I think it's a forest? If that is the case, it would be good to place some trees in the space between the two main trees and the rest of the forest.
Yes, the text is clearly legible. It's very pretty.
)
