Mice have to eat too, and phloem is good stuff. If there are still intact strips of bark, wrap with burlap to deter mice. If bark removal is in a complete circle, you'll lose those trees.

Mice. If bark is gone all around the stem it will die. Otherwise wrap burlap around the injured stem to keep mice off it.

Thanks, There are a lot of mice in the open space and fields. The bark was chewed all the way around. What a shame. These were so well taken care of and was pushed to grow as fast as possible as a shield from some townhomes nearby. This was the first year I didn't put chicken wire around the trees. that's why I thought for sure it was the rabbits. We have lots of them, too.

Hi Genie9, sorry about your tree loss. Probably just an annoying bit of detail to you, but what are being referred to as mice are very likely actually voles. But hey, they look like mice, and they sure do eat a lot of plant bark.

As the gentlemen above have suggested, it is not too late to protect what hasn't been completely girdled. Since you've put considerable effort into this planting, you may as well go the extra step and try to save what you can.

Incidentally, rabbit damage will resemble small branches very cleanly cut off, almost as if by a hand pruner. But that bark damage is indeed voles.

+oM

For future reference, for protection against trunk bark gnawing you don't need chicken wire -- rather, what works best is a spiral plastic wrap (ie. spiral-cut tube) you can get at your local nursery, and then cut to various size pieces to suit the plant.
Personally, I use it for protecting Japanese maples -- which the voles find far more tasty than conifer bark -- and which are also much more expensive !
Good luck (for next time).