Most of California's forests have never been surveyed for owls. In 1993, Steven Self and Thomas Nelson, researchers employed by Sierra Pacific, estimated that California alone is a home to between 6,000 and 8,000 pairs of spotted owls. Federal Documents estimate somewhere between 3,000 and 4,000 pairs of spotted owls exist in the entire United States. It was on these federal figures that the logging ban in the northwest was based. This could be due to the fact that the floors of young forests are more alive than that of old growth forests.
Ancient forests have a low level of life.
This is due to the closed canopy, which does not permit direct sunlight to reach the understory of the forest. In turn, you have plants that grow slowly and fewer seeds for small mammals to feed upon, thus fewer animals for the spotted owl to feed upon. In younger forest, the understory is alive. In the managed forests of California the trees have been spaced and trimmed permitting sunlight to reach the forest floor. The result is lots of food for the dusty-footed woodrat that the spotted owls of California prey upon, therefore lots of spotted owls.