In Nevada, hummingbirds embark on a journey that requires a lot of their time and energy. This journey, known as migration, is necessary for their survival. While no one knows for sure what prompts hummingbirds to migrate, a chemical change in their bodies may signal that it's time to leave one location in order to secure food resources in another. Because their preferred foods—flowering plants and insects—do not survive in cold temperatures, hummingbirds must move to warmer, southern climates before winter comes. They return north only when flowers are back in bloom and insect populations rebound.

A hummingbird must consume lots of food to sustain its long journey. Nectar from flowers is high in energy, but the protein, vitamin, and mineral needs of hummingbirds are provided by the insects they eat. By the time a hummingbird begins its migration, it will have increased its body weight by 25 to 40 percent. However, migration takes a toll: a hummingbird completes its journey at well below its normal weight. While the distance covered and the destination for each hummingbird species vary, studies show that each individual bird follows the same route every year. In fact, it's not uncommon for a hummingbird to annually visit the same backyard feeders.

Hummingbirds migrate alone for strategic reasons. First, flocks are more visible to predators. Also, because most hummingbirds stop frequently to feed, traveling in flocks would result in greater competition at flowers or feeders and a lot of waiting time. Finally, because of their small size, hummingbirds derive no aerodynamic efficiency from flying in each other's wake, as other flocking birds do. However, they do use the wind to their advantage. They are more likely to fly when winds blow in the direction of their destination.

Unless the migration route is entirely over water, hummingbirds fly during the day and sleep at night. They fly just above tree level over land or near the surface over water, probably to spot food sources. They may encounter strong headwinds or storms, sudden shifts in weather, a lack of food sources, and even unfamiliar predators—all of which may prove fatal. The first thing survivors do when they reach their destination is fatten up. Males then focus on attracting a female to their territory, while females begin nesting.

To learn about the different traits and adaptations in various hummingbird species, check out A Variety of Hummingbirds.

To learn more about the migratory patterns and habits of the Rufous Hummingbird, check out Little Brain, Big Journey.

To learn how natural selection works in hummingbird populations, check out Evolving Ideas: How Does Evolution Really Work? and Hummingbird Species in the Transitional Zones.

To view a hummingbird's beak in relation to that of other birds, check out Bird Food and Bird Beak Gallery.

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