It's a pretty big problem out here (front range of Colorado) they eat the crap out of trees (mainly Siberian Elms but also Locust, Hackberry, Ash, etc.) , some years are worse than others. I think the starving part may have something to do with it not sure. Pretty sure squirrels aren't meant to be here but then again neither are trees. When I first came out here from the midwest and had to trim a squirrel damaged tree I was like WTF, they aren't supposed to eat the tree.