In the early spring their main diet is tree buds which have a lot of stored energy for the year's growth. To a squirrel this means good nutrition. Once the buds are gone they switch to the tree blossoms. We are seeing young squirrels out on the very tip of a branch, swaying in the wind.
|Young squirrel reaching for twig tips - REK|
Squirrels will chew tree bark and twigs and no one knows why for sure as they can't digest cellulose. They will use strips of tree bark in their nests but at other times they seem to chew just for the heck of it. As rodents with constantly growing teeth they may be doing it to keep wearing their teeth down like a beaver. We have a constant battle with ours chewing the painted shingle siding which covers an underlying concrete wall. When I covered it with thin aluminum sheeting they chewed it!
Any skull or antler left in the woods for too long will have signs of squirrel chews. The theory is that they are getting calcium which is otherwise missing in their diet, although it could be for tooth wear as well. I leave an old deer skull on our deck which is chewed on daily but one squirrel still is chewing on our house.
Eastern gray squirrels are very territorial and will mark their area with urine and tree chews. They will chew bark and rub it with oral scent glands to mark their territory. A certified wildlife tracker friend spotted one of these marks on a large oak wolf tree in the middle of a field.
A final thought about what squirrels chew. They are rodents. Chewing is what rodents do. They have rootless teeth that are constantly growing and need to be worn down. It is not their problem, it is ours.