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Hummingbirds evolved to display unique adaptations and anatomy allowing them to survive in several climates. They are easily identified by their small size, vivid coloring, long beaks and rapid wing movement. More than 300 species of hummingbirds are known to exist today, and habitats range from tropical to temperate climates. Hummingbirds can be found feeding from brightly colored flowers.
Beak and Tongue
Hummingbirds have a long, narrow beak that allows them to reach the nectar from brightly colored, tubular flowers. They also feed on insects and have a flexible lower beak that allows them to grab insects from the air during flight. The tongue, like the beak, is quite long, and the tip is covered in hairs to pull more nectar from flowers.
Hummingbirds have an excellent memory and can recall any feeding source they have used in the past. According to the website World of Hummingbirds, a hummingbird brain accounts for 4.2 percent of the hummingbird's weight. In the bird kingdom, hummingbirds have the largest brain in proportion to body size.
A hummingbird's eyes are located on the sides of the head and are very large in comparison to the size of the bird. The location and size of the eyes allow the bird to see both in front and to both sides simultaneously. Hummingbirds see colors similar to the ones we see, and also have the ability to see ultraviolet wavelengths. The eyes are protected by at least 12 bones called ossicles.
Heart and Lungs
Heart rate in hummingbirds is extremely high during flight, reaching up to 1,250 beats per minute. Resting heart rate drops to approximately 250 beats per minute. This allows the blood to circulate quickly, delivering oxygen to the muscles during rapid muscle movements of flight. The lungs of a hummingbird serve to both deliver oxygen into the bloodstream and help cool the hummingbird. The respiration rate for these birds is approximately 250 breaths per minute—about four breaths each second.
Wings and Muscles
The main muscles hummingbirds use in flight are the pectoralis majors. These muscles are almost entirely made up of Type I, fast-twitch muscle fibers, allowing the wings to beat up to 200 times per second. Unlike other birds, hummingbirds can fly both forward and backward and change directions quickly. The shoulder joint allows the wing to rotate up to 180 degrees, allowing for the fast and precise movements. According to the World of Hummingbirds, they can reach speeds of 60 miles per hour during a dive.
Hummingbirds have adapted to survive in conditions with cold weather and limited food. They do this by reducing their metabolism and entering a state called torpor. Typically a hummingbird's body temperature is 105 degrees Fahrenheit. During torpor, body temperature drops to as low as 70 degrees, allowing the bird to survive until conditions improve.
Female hummingbirds are born with two ovaries; however, soon after birth the right ovary disappears. This helps make the bird lighter for flight. If an egg is fertilized, the female will lay the egg in a nest; unfertilized eggs are reabsorbed into the body. Male hummingbirds produce sperm in the testes, but do not have a penis. Reproductive organs in both males and females shrink during non-breeding months to decrease the female's weight during flight and migration.
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