In the wild gray and fox squirrels most heavily rely upon nuts, tree pod seeds, fungi, tree buds and the inner layer of bark from specific food trees for their diets, which provide them high amounts of plant protein. Animal protein sources, that they are known to also consume, are relied upon to a far lesser extent; these include: insects, insect larva, carrion, bird eggs, and most rarely birds. In captivity, ground grains, including corn, are used primarily for reason that they are lower in fat than tree grains for captive care diets; yet they are higher in carbs proportionally that the natural grain sources in the tree squirrel wild diet. Using a high amount of animal protein in the diet can work for rehabbing, but isn't an optimal main source of protein to use for use in NR diets. Hulled Oats (no bran) are a good secondary source in place of wheat.