With upwards of 10,000 species of birds globally, I wanted to find out how diverse birds are. The diversity between species of birds is incredible, from the tiniest sparrow to the giant eagle. Find out why birds are one of the most diverse animal groups.
The diversity of birds can be seen in their different habitats, geographical locations, the shape of their bills, and feet and toes. Their size, colors, diet, and ways of flying are also very different.
Please read on if you want to learn more about why birds are so diverse.
Different Species and Orders
There are roughly 10,000 species of birds globally, with estimates of almost one thousand in North America.
Birds can be found in many habitats, from tundra to deserts and almost everywhere. For a bird to live in a specific habitat, they have to survive against predators and be able to find food.
Birds live in various habitats, including tundra, forests, deserts, seawater and freshwater, rainforests, and mountainous regions.
The size of a bird affects its range size, which also affects its population size. Large species are usually less abundant than small species. If their range size is small, this will also affect their population size.
Few species of large birds have small ranges as they prefer an extensive range. However, small birds do not always stick to smaller ranges and can often be found in vast fields.
A bird’s beak varies depending on the type of food they eat. Birds with a less-varied diet will have a bill shaped to get to their preferred food.
Finches have a wedge-shaped bill allowing them to crack seeds using a nutcracker motion. Parrots can crack a nut’s shell using their powerful statements before pulling out the nut with the down-curved tip.
Toucans have large bills, which they use to cut off fruit from the tree before slicing it into manageable chunks.
Some birds, such as the godwit, have a long up-curved bills. They use this to pick up aquatic prey. Whimbrels have a down-cured statement to dig in the sand for crabs, mollusks, and fish.
Crossbills feed on spruce and pine cones, which they pry open with their bills. Their upper and lower mandibles cross, making this an easy task.
Grosbeaks have stout bills, which they use to eat seeds. The woodpecker’s beak is straight, allowing them to get to ants by chiseling at the tree. Nuthatches have long bills that enable them to get into crevices.
Species of birds such as nightjars and swifts have short bills, which allows them to catch insects while in flight. Orioles use their accounts in a variety of ways. They can snatch caterpillars and insects from trees and use their account to stab fruit. They then open their mouth, which cuts into the fruit, allowing them to drink from it.
Feet And Legs
Further diversification between birds can easily be seen in their legs and feet. Birds’ legs and feet are different according to the functions they need to perform.
Bird’s toes often point forwards and backward. Some species of woodpeckers have two facing forwards and two facing back. This allows them to hang onto the sides of trees easier.
Depending on the species, most have three facing forward and one pointing backward. However, some species do not have a backward-facing toe. Birds can have 2, 3, 4, or 5 toes.
Some birds walk on their toes (digitigrade). However, others will walk flat on their feet, with their heel on the ground.
Birds can use their feet to walk, run, hop, climb, swim, steer, perch, catch and kill prey, and scratch, among others.
Some birds have webbed feet, such as ducks, geese, and swans, although this is generally limited to aquatic birds. The webbed feet help them to swim and steer when in the water.
Some species, such as coots and grebes, have lobed feet. These are long and help the bird walk on soft, uneven surfaces. These stiff flaps are found along both sides of the toes.
All birds have claws on the end of their toes. The forelimbs of a bird are the wings.
Birds range in size from the smallest bird in North America, the Calliope hummingbird, to the California Condor. The Californian condor has a wingspan of up to 9 1/2 feet and weighs up to 23 pounds. The Calliope hummingbird is tiny at 3 inches (8 cm) long and weighs 0.1 oz.
The body size determines the life history of the bird. Larger species tend to live longer and breed later in life. They also have a longer breeding cycle and fewer young. Some large birds do not start producing until they are ten years old and may lay just one egg with an incubation period of 2 months.
This is in stark contrast to some smaller birds, which start to breed in their first year and lay up to 12 eggs. Smaller birds generally have a lower incubation period than large birds, typically a couple of weeks, and may have two breeding periods in a year. This inevitably leads to a larger population of small birds than large birds.
Although large species generally live longer than smaller species, some exceptions exist. Tiny hummingbirds only lay two eggs, whereas an ostrich can lay up to 10.
With such a vast range of species, there should be no surprise that almost every color can be seen on a bird. Birds have a wide diversity of patterns and colors in their plumage.
The colors are used in various ways and can aid courtship or display a threat. Colored plumage can also be used as camouflage from prey and predators. Generally, only the parts of the feathers that can be seen are brightly colored, with those concealed being dull.
Colors on feathers are produced by pigments called melanins and lipochromes. These two pigments have different colors on the feathers.
Lipochromes produce reds, oranges, yellows, greens, and blues. Melanins have darker colors like black, brown, reddish-brown, and yellow. Colors are sometimes related to the bird’s diet, with crows and ravens needing plenty of riboflavin to achieve their color. These pigments can also protect the bird from ultraviolet rays from the sun.
There is another diversity within the colors of birds. Colors are either iridescent or non-iridescent. Non-iridescent colors can be seen from any angle, but iridescent colors, such as those on hummingbirds, can only be seen from certain angles.
Although birds of different species have a diversity of colors, birds of the same species can also have different colors depending on where they live. Birds that live in shady areas may be different colors from those living in areas with lots of suns. This is due to some colors fading in bright sunlight.
Flight is an adaptation that birds use to move around. However, birds do not need all fly in the same manner and use several different methods.
We are used to seeing birds flap their wings. In this flight method, birds flap their wings up and down to propel themselves through the air. On the upstroke, the wings are held so that the wingtip moves closer to the body. On the downstroke, however, the wings move downward parallel to the body.
The downstroke generates thrust and allows the bird to fly straight and level, whereas the upstroke can provide lift.
The amount of times the wings are flapped depends on the species and size of the bird. Hummingbirds can beat their wings 80 times a second, whereas some herons flap their wings twice a second.
Although all birds that can fly use their wings in this manner, the diversity of flight in birds can be seen by species that use thermal currents to soar and glide. Some species save energy by riding these air currents to great heights. By locking their wings, the thermal air currents allow them to flow without using power to flap their wings.
Soaring is generally only used by larger birds, such as birds of prey, and sea birds, such as albatrosses and gulls, although ravens, storks, and herons also use this flight method.
Birds can use the thermals to reach heights before gliding off to new territory. Once they get a new thermal, they can begin to climb again. Soaring is used to search for a few reasons, including hunting for food and during migration.
Whereas soaring is reserved for large bird species, hovering is a means of flight by some of the smallest birds. Hummingbirds hover to reach areas that would be difficult to get, such as plants that would collapse even under their little weight.
The hummingbird can support their weight without propelling themselves forward by fully extending their wings and flapping very fast. They do this by slanting the body upwards, causing the flight feathers to beat horizontally. They then flap their wings in a figure of eight, with the downstroke being a forward stroke and the upstroke a downwards stroke.
Birds such as the blue tit use a bounding flight effect. In doing this, they interchange moments of flapping their wings into a state where they keep their wings directly against the sides of their bodies and follow their path.
The undulating flight is similar, whereas it is moments of gliding followed by flapping. Both of these methods can be used to save energy in flight.
There is another method that some birds also use to save energy when flying. This can be seen when you watch a bird that passes close to the ground. The ground helps reduce drag on the wings, helping to save energy.
Although we think of birds as animals that use their wings to fly, there are over 60 species that cannot fly at all, further diversifying birds from each other.
Flightless birds are limited to a specific order, and many orders also include birds that can fly.
Another way to see how diverse birds are is to study their diet. Birds can eat a wide variety of foods. The diet of a bird will generally depend on the species and size of the bird.
Larger birds, such as birds of prey, will eat other birds, mammals, rodents, frogs, fish, and crustaceans. Smaller birds may eat insects, earthworms, snails, fruit and berries, spiders, seeds, other birds, mammals, rodents, frogs, fish, crustaceans, and plants. However, a bird’s diet depends on its species and habitat.
Bryan Harding is a member of the American Society of Mammalogists and a member of the American Birding Association. Bryan is especially fond of mammals and has studied and worked with them around the world. Bryan serves as owner, writer, and publisher of North American Nature.