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 do not spend all day flying, as the energy cost would be prohibitive; the majority of their activity consists simply of sitting or perching. 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.wo studies of rufous or Anna's hummingbirds in a wind tunnel used particle image velocimetry techniques to investigate the lift generated on the bird's upstroke and downstroke. The birds produced 75% of their weight support during the downstroke and 25% during the upstroke, with the wings making a figure 8 motion.