Unprotected trees are targeted by wildlife.
When trees are initially planted in the open space, cages protected them from goats and other predators. As the trees grew, the cages became too small and were removed. Damage has been observed on these unprotected trees this past year. There are about 17 trees without cages in the open space and most appear to have the same damage, barks appears to be rubbed off the trees.
After consulting with the Resource Conservation District, Solano Land Trust, and UC Extension, it appears the damage is from deer rubbing the velvet from their antlers. Deer shed their antlers in winter when the bone cells in the antlers die. Deer grow new antlers for the new year and the new growth is covered in a fuzzy skin that helps called velvet that helps nourish the bone growth. During the spring, deer typically rub their fuzzy new antlers against trees to strengthen their neck muscles and mark the tree with their scent. Click on the website Sciencing for an interesting article on deer antlers.
Cages, again, appear to be the appropriate solution. The new cages will be about 3′ in diameter, providing the tree with room to grown while also providing protection from deer. We hope to install the cages this spring. When the tree trunks get bigger in a few years, we can try removing them and see if they can co-exists with the wildlife on their own.