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.
1 What to feed hummingbirds and how to choose a hummingbird feeder. 2  Learn about how to make hummingbird food, keep ants out of the nectar, and more in our FAQ section. 3  Print out our BirdNote on Attracting Hummingbirds (PDF).  Study up on your hummingbirds in our All About Birds online bird guide.