Costa's hummingbird, Calypte costae, occurs in deserts and coastal shrublands in the southwestern United States and northwestern Mexico. Similar to other hummingbirds, this species feeds primarily on nectar, but insects (a primary source of protein) are also an important component of the diet. Increased protein intake is especially important to females producing eggs, and insects are probably a major component of food provided to growing chicks.
Males and females do not form pair bonds, and males do not participate in nest building, incubation, or nestling care. Females construct nests of feathers and small pieces of plants bound together with spider silk. Nests are usually small and flimsy compared to other hummingbird nests, possibly because there is little risk of nest damage from rain in the deserts. Nests are often built four or five feet above the ground on a dead yucca stalk, a cholla cactus, or a shrub. Two eggs are laid and incubated for 15 to 18 days, and young leave the nest after 20 to 23 days.
In Utah, this hummingbird is present only from March through June, most commonly in the Virgin River drainage in southwestern Utah. Although it is present only during the breeding season, no nests have been located in Utah. This may be related to the difficulty of distinguishing the female Costa's hummingbird from the female black-chinned hummingbird, a common species in Utah.