Hummingbirds (Family Trochilidae) are birds known for their small size, nectarivory, long beaks, and rapid movements. They have the highest metabolism of any warm-blooded animal, requiring high-sugar nectar just to maintain it. Their main nutritional diet, however, comes from insects. Their wing beats are so rapid, that the human eye cannot see them, but they do generate a deep buzzing sound similar to that of bees. The rapid movements of their wings cause them to be the only bird that can fly backwards. Hummingbirds are also the smallest species of bird. The smallest is the Bee hummingbird (Mellisuga helenae), averaging a weight of two grams.
Hummingbirds live in a variety of climates up and down North and South America. Most species live in tropical and semi-tropical areas, but some species live in temperate regions as far North as Southern Alaska, and high altitude as the Andes Mountains. There are no Hummingbirds native to Europe, so historical Vikings would not have known about these birds.
In the Book series, Hummingbirds are used as a metaphor for other creatures.
In reality, Hummingbirds are occasionally kept in zoos and aviaries. The Hummingbird also figured into some historic South American native cultures, such as a manifestation of the Aztec God, Huitzilopochtli.
Semi-Spotted Snowpeckers, a fictitious bird seen in Book 4, are said to "flit about like hummingbirds." Indicating they have very fast and exaggerated movements.