The quarrelsome Allen's Hummingbird, a bird of the American West, is almost impossible to watch in flight as these tiny birds are incredibly fast. That speed is most likely a result of it's rapid metabolism and high body temperature (around 108 degrees F or 42 degrees C). I intercepted the birds in the photographs below on their fall migration route; dozens of them were fighting over a small patch of thistle blossoms high on the slopes of Mt. Charleston in the Spring Mountains of Nevada. The energy the birds utilized in two hours of bickering would have gotten them to their wintering grounds in northwestern Mexico!