Typical squirrel dens are formed by self-pruning of trees within the forest stand as lower limbs are shaded, die and drop off.
(Typical squirrel dens; are formed; by self-pruning of trees) (lower limbs; are shaded; ) (lower limbs; die; ) (lower limbs; drop off; )
Typical squirrel dens lower limbs lower limbs lower limbs
are formed are shaded die drop off
by self-pruning of trees