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.
Other birds, such as orioles and roadrunners, occasionally eat hummingbirds. Even though hummingbirds are small in size, they have a large appetite. Their diet is mostly liquidânectarâand these birds get plenty of exercise with all that zipping around just to get from sip to sip.