Lower half of the tree -- likely to be a woodchuck. They can and do climb, I've had them climb into my younger, smaller trees and strip the lower half -- I guess they don't like the wobbly outer branches, too thin to support their weight.

If it's higher up, most likely deer.

The trees will recover, as long as the new growth isn't continuously stripped.

I would think deer would eat the apples and pears

If it is an animal there will be a bite mark, usually deer bite off a leaf leaving half an inch or so of stem left. Bugs on the other hand will not leave such a clean break. Please describe what fragments are left of your eaten leaves, and if there are leaves missing that are taller than any deer could reach.

Scott

I have a similar issue with two pear trees and a peach. All of the leaves are missing from about four feet down. Most of the leaves look like they were cut where the leaf and stem meet, leaving a tree of stems! The others, the leaves and stems are missing, however above four feet, they look normal. The trees are about six feet in total and were planted about 2 months ago.
Thank you,

pmorris that sounds just like deer.

Scott