ALL LIFE ON earth, either directly or indirectly. Plants obviously must have sunlight or full-spectrum artificial light to manufacture their food by photosynthesis. Plants, in turn, pass on their energy to the animals that consume them.
Light is also essential for the survival of most animal species.
Obviously, it is required for vision, and most birds have highly developed sight. Full-spectrum light may be needed for the maintenance of health in ways still unknown, add, finally, light is important for the psychological well being of animals. Avian species, including nocturnal birds, are highly dependent upon sight for survival. The avian eye displays the basic pattern of a vertebrate's eyes, but it incorporates many adaptations that have improved visual abilities. The avian eve is considered to be the finest ocular organ in the animal kingdom.