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.
Hummingbirds eat many small meals and consume around half their weight in pure sugar (twice their weight in nectar, if the nectar is 25% sugar) each day. Hummingbirds digest their food rapidly due to their small size and high metabolism; a mean retention time less than an hour has been reported.