Metabolism

Hummingbirds are found only in the Americas, from southern Alaska to Tierra del Fuego. Only the migratory Ruby Throated Hummingbird breeds east of the Mississippi River. They migrate south in fall to spend the northern winter in Mexico, crossing 500 miles across the Gulf of Mexico in a nonstop flight. A few species are year round residents in the warmer coastal regions, such as Anna’s Hummingbird, a common resident from southern California to British Columbia.

Hummingbirds have the highest metabolism of all animals, a necessity in order to support the rapid beating of their wings. Their heart rate can reach as high as 1,260 beats per minute. Their wings beat at about 25 cycles per second, which produces their characteristic humming sound. They typically consume more than their own weight in nectar each day, and to do so they must visit hundreds of flowers daily. At any given moment they are only hours away from starving. Most organisms with very rapid metabolisms have short life spans. However, hummingbirds have been known to survive for as long as 17 years.

The bill of the hummingbird is one of its most distinctive features. It protects a long tongue with a brushy tip that is used by the hummingbird to lap up nectar. The tongue itself splits in the floor of the mouth and the two rear segments wrap under the jaw, behind and over the head, and attach at the front of the skull. It contains only a few taste buds and salivary glands.

Hummingbirds feed on the nectar of plants and are important pollinators, especially of long, tubular flowers. Like bees, they are able to assess the amount of sugar in the nectar they eat. They reject flower types that produce nectar which is less than 15% sugar and prefer those whose sugar content is around 25%. Nectar is a poor source of nutrients, so hummingbirds meet their needs for protein, amino acids, vitamins and minerals by consuming insects and spiders, especially when feeding young.

Hummingbirds will consume sugar water from artificial feeders. Such feeders allow us to observe and enjoy hummingbirds up close while providing the birds with a reliable source of energy, especially when flower blossoms are less abundant. Only white granulated sugar is proven safe to use in hummingbird feeders. A ratio of 1 cup sugar to 4 cups water is a common recipe.

The Sword-billed Hummingbird is found in the Andes. It is noted as the only species to have a bill longer than the rest of its body. This adaptation is to feed on flowers with long corollas such as Passiflora mixta. The tongue is therefore also unusually long. Since the beak is very long, it grooms itself with its feet. The total length can be 6 inches, making it one of the largest hummingbirds.

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