Typical squirrel dens are formed by self-pruning of trees within the forest stand as lower limbs are shaded, die and drop off. Decay may begin at these spots before the opening heals over. Trees growing in the open are less susceptible to this type of den formation. Gray squirrels usually live near open water, yet both species can survive for many days without trips to pools or streams. Succulent foods, snow, frost and dew are other sources of water.
Convenience seems to determine which sources are used most often.
However, permanent water should be available to squirrels for drouth emergencies. Squirrels can be expected to live within a quarter to a half mile of permanent water during droughs. If permanent water is not available at such times, squirrels will migrate to an area where it is present. The speed with which squirrel habitat develops and the degree of success attained depends upon overall objectives, perseverence and the use of special techniques such as nest boxes. Dens can be built from auto tires, rough lumber, sawmill slabs, nail kegs, or small hollow logs cut in sections.