Uncontrolled fires may move much faster and burn at higher temperatures than prescribed fires, posing a much greater risk to wildlife and humans alike. During prescribed fires, however, a greater level of control is exerted over these factors by selecting environmental conditions that minimize risks. For example, prescribed fires are not approved by the Florida Division of Forestry during overly dry conditions or when wind speeds are too high. Various studies and observations suggest fire typically causes little direct mortality to large mobile animals such as deer, bobcats, and bear. Even during the extensive wild fires at Yellowstone National Park during 1988, helicopter surveys revealed a surprisingly low number of deer and other large animals had been killed by fire.
Young animals are at greater risk of being killed by fires.
But even at young ages, deer and other mammals are highly mobile and have been observed avoiding fires. Conducting smaller prescribed fires, avoiding the practice of re-lighting unburned patches, and avoiding burning during peak birthing periods can reduce mortality among young individuals. Destruction of bird nests by fire, particularly among shrub and ground-nesting species, is a chief concern of wildlife managers. Attempts to protect nests have resulted in recommendations by some biologists to burn only during the winter months or after the nesting season. If their nests are destroyed, however, most birds will attempt to re-nest.