http://www.ck12.org Chapter 12. Understanding Biodiversity: Animals: Birds
Habitat
C. annalives 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.
Biology
Cell Biology
C. annahas 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.
Evolution
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 calledDeinonychus.Deinonychusis 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.
Ecology
Some predators of Anna’s hummingbird are western scrub-jays, American kestrels, greater roadrunners, and curved-
billed thrashers.C. annais 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. annaeats small
insects, spiders, nectar, sap, and sugar-water mixtures from feeders. Apparently male hummingbirds have a close
coevolutionary relationship withRibes 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. annahas 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