Causes and symptoms. Fatigue may be the result of one or more environmental causes such as inadequate rest, improper diet, work and home stressors, or poor physical conditioning, or one symptom of a chronic medical condition or disease process in the body.
1 A hummingbird will use its tongue to lap up nectar from flowers and feeders. 2  A hummingbird's tongue is grooved like the shape of a W. 3  Hummingbirds have tiny hairs on the tip of the tongue to help lap up nectar.
What do sunbirds eat? by BESG | posted in: Feeding-invertebrates, Feeding-plants, Sunbirds | 29. Sunbirds are a group of small Old World passerine birds that feed mainly on nectar but also take insects and small fruits (left top). When feeding their young, insects are the main diet. Sunbirds are considered the jewels of the Old World tropics. Many species, especially the males, possess glittering iridescent colours. In morphology and nectar feeding behaviour, they remind one of the hummingbirds of the neotropics. In both groups, the females are plain. But sunbirds and hummingbirds are definitely not related. Sunbirds are omnivorous, feeding primarily on nectar and insects.