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12.4: Calypte anna: Anna’s Hummingbird

Difficulty Level: At Grade Created by: CK-12

Common Name

  • Anna’s Hummingbird

This bird was named after Anna Masséna, Duchess of Rivoli.


Calypte anna is a very common hummingbird on the West Coast of North America. They are stocky, medium-sized hummingbirds. Anna’s hummingbird is about 10 cm (4 in.) in length, with a wingspan of 12 cm (5 in.), and weighs about 3 - 6 grams. C. anna has a bronzy green dorsal area, a medium-length bill, and a broad tail. The males can be identified by their bright rose throats and dark tails. Females have a dull mix of gray and white, or gray and brown, and a white-tipped tail.

Males are well known for their mating rituals of flying up to a height of 130 feet to plummet to the ground, pulling up at the last second, making beautiful noises with their tail feathers. Hummingbirds are the only birds that can fly backwards.

The complete taxonomic classification is:

  • Kingdom: Animalia
  • Phylum: Chordata
  • Class: Aves
  • Order: Trochiliformes
  • Family: Trochilidae
  • Genus: Calypte
  • Species: C. anna


C. anna lives on the western coast of North America. Their breeding range is from British Columbia to Arizona. They are permanent residents on the West Coast of the United States. Anna’s hummingbird lives in open woods, shrubs, gardens, and parks. During breeding season, males live on canyon sides and hill slopes, while the females live in trees, such as oak and evergreens. In the summer Anna’s hummingbird lives in higher elevations, and in the winter they live in lower elevations.


Cell Biology

C. anna has many eukaryotic cells, like all birds and other animals. Eukaryotic cells have a nucleus and many organelles. Organelles are a number of specialized structures within a cell. Some examples of organelles are the nucleus, mitochondria, vacuoles, ribosomes, and the endoplasmic reticulum. These organelles all have different functions to keep the cell healthy, so the body can keep working. The nucleus contains DNA that has information on how to build thousands of proteins. The mitochondria provides the energy (ATP - adenosine triphosphate) the cell needs. Ribosomes produce proteins. Vacuoles act as storage centers, storing water and nutrients. The endoplasmic reticulum transports proteins within the cell.


Theropods are a group of bipedal dinosaurs that birds are thought to be evolved from. The ancestor of birds is very similar to a theropod called Deinonychus. Deinonychus is an extinct predatory carnivore with very many bird-like features. They lived about 110 years ago in North America. Evolution of flight is still unknown, for scientists have some theories, but are not 100% sure yet. One of their theories is that wings were evolved from a bird ancestor that lept to catch prey or to avoid predators, therefore developing wings from their arms to help them leap higher. Another theory was that the wings were evolved from a bird ancestor that lived up high in trees. Therefore wings were modified arms that helped the animal glide from tree to tree. Birds have evolved over thousands of years, to what they are today.


Some predators of Anna’s hummingbird are western scrub-jays, American kestrels, greater roadrunners, and curved-billed thrashers. C. anna is a pollinator. Its favorite flowers are long, tubular flowers in red, orange, violet hues. Some of these flowers are azaleas, fuchsias, pitcher-sage, Indian warrior, and the monkey flower. C. anna eats small insects, spiders, nectar, sap, and sugar-water mixtures from feeders. Apparently male hummingbirds have a close coevolutionary relationship with Ribes specious, commonly known as fuchsia-flowered gooseberry. We benefit from the Anna’s hummingbird because it pollinates a wide variety of flowers.

Anatomy and Physiology

These hummingbirds have long, extendable, straw-like tongues that help them get the nectar that are deep inside flowers. They have a lifespan of 8.5 years, reaching sexual maturity at a year old. Anna’s hummingbirds lay about two eggs per breeding season. These eggs take about 14-19 days to hatch. C. anna has wing flexibility, and their wings can beat at a speed of 25 beats per second or 1500 beats per minute. Anna’s hummingbirds have the largest brain-to-body size of any bird, giving them a phenomenal memory. The pneumatic bones of an Anna’s hummingbird are hollow and only air-filled. C. anna has a four-chambered heart. That is very important since hummingbirds have such a high metabolism. Their respiration is in two cycles, unlike mammals who only have one cycle. These two cycles provide huge amounts of air and helps remove excess body heat. During the first cycle, they inhale air from the posterior air sacs and then exhale air from the posterior air sacs to the lungs. When the air enters the lungs, this is the oxygen/carbon dioxide exchange site. During the second cycle, air inhaled from lungs go into anterior air sacs. From the anterior air sacs, air is exhaled out of the primary bronchus. The primary bronchus is one of the two main air passages that branch from the trachea.

Digestion is a very important part of the bird’s body. The crop is an enlarged extension of the the esophagus. Here they store food for digesting later or to feed their chicks. The proventriculus is the anterior glandular stomach that produces gastric acids and digestive enzymes, just like in our stomachs. After the proventriculus, the food goes to the gizzard. The gizzard is the posterior muscular stomach. Its main purpose is to grind food. The gizzard may need to be aided with rocks or stones, called gastrolith.


Anna’s hummingbirds are not social animals. They will dive at anything that comes near their territory. The Anna’s hummingbird migrate in the fall and spring. To conserve energy, the Anna’s hummingbird are active during the day and become torpid at night. Male Anna’s hummingbirds have a special mating ritual. The male flies to a height of 130 feet, and plummets down to the ground pulling up at the last minute, making a beautiful sound through their tail feathers.

See The Courtship of Anna's Hummingbird (Britannica.com) at http://www.youtube.com/watch?v=NMErQg0dFDs for a further description of this mating ritual and these birds.


  • http://www.naturebytesvideo.com
  • "All About Birds." Anna's Hummingbird, Identification,. N.p., n.d. Web. 12 Mar. 2013.
  • Bailey, Dave. "What Is a Bird?" San Diego: Mission Trails Regional Park Trail Guide Training Program, 2008.
  • Book of North American Birds. Pleasantville, NY: Reader's Digest Association, 1990. Print.
  • Calypte Anna — Details. Encyclopedia of Life. N.p., n.d. Web. 26 Mar. 2013.
  • Chinery, Michael. The Grolier Illustrated Encyclopedia of Animals. Vol. 2. Danbury, CT: Grolier Educational, 1994. Print.
  • Peterson, Roger Tory. Peterson Field Guide to Birds of Western North America. 4th ed. Boston: Houghton Mifflin Harcourt, 2010. Print.
  • Sibley, David. The Sibley Field Guide to Birds of Western North America. New York: Knopf, 2003. Print.
  • Udvardy, Miklos D. F. Field Guide to North American Birds. New York, NY: Knopf, 1998. Print.



  • Hilary Castaneda
  • Victoria Nguyen

Supervising Faculty

  • Amy Huff Shah


  • Museum School, San Diego, California


  • Published prior to review.

Edit History

  • Created: April 5, 2013
  • Version 1.0 submitted to CK-12: July 2, 2013
  • CK-12 edits: in progress


  • Middle School (grades 6-8)

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Date Created:

Jul 08, 2013

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Jan 30, 2016
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