Birds can be used as environmental indicators to assess the health of an environment. Every year migratory birds may return to the same breeding territories. Evidence of a declining bird population in a particular region may indicate another problem present in the habitat, perhaps the disappearance of their food source or preferred nesting sites. The decline of the Kentucky Warbler in certain regions can be attributed to the overpopulation of white-tailed deer. Excessive numbers of browsing deer can devastate the plant life that would normally provide cover for the warbler nests.
Birds are natural enemies of many insects.
In turn, as the immense insect population feeds, local plant life will suffer. Despite the significant role birds play in local ecosystems, every year the numbers of migratory birds that return to our region decreases. Migrating birds are amazingly tough on their long journeys. They can usually survive bad storms, high winds and threats from a variety of predators. But believe it or not, humans are their biggest threat.