Birds are some of the most lucrative vertebrate animals on earth. They are spread all across the world and you can spot them anywhere.
Approximately, more than 95 percent of global bird species diversity has been specified. According to research by some ornithologists as well as scientists, it is known that there are practically between 9,000 and 10,000 species of birds. However, these are just estimates based on biological concepts of what birds can breed together.
Although, this research is an underestimate of the growing species of birds all over the world.
How Bird Classification Works
No matter the kind of living organism on this planet, they are all coordinated into a classification system so that scientists can keep track of which animals are which. Birds are classified according to their similarities as well as differences.
The hierarchy is organized into orders and then those are divided into families and finally into genera. The whole hierarchy is precisely portrayed down below.
- Order
The figure of 29 orders of birds keeps updating as there is continuous research going on about bird biology. The relation between groups of similar birds is becoming better understood by the day.
The significant changes in the classification of birds are a result of the new research using DNA analysis. This analysis is even better than the previous ways of morphology as it helps to determine how closely two species of birds are related so they can be put in a certain group together.
- Family
The orders of birds are divided into 233 families out of which 83 species dwell in North America. Similar to the bird orders, both the number and composition of the bird families are always fluctuating. Again, this is due to the constant ongoing research between the different kinds of birds.
Many families of birds such as the Laridae used to include all species of Gulls, Terns, Skuas, Jaegers, and Skimmers. Whereas now, there is sub-division of this family into four distinct families of Gulls, Terns, Skuas and Jaegers, and Skimmers.
- Genera (singular: genus)
The main thing that divides the family group and individual species of birds is the genus. This means that the collection of an individual and a group of a family can form a taxonomic unit which is known as the genus.
As per research, you may know that a large number of waterfowls in North America are a representation of the 61 ducks, geese, and swans. They all belong to the family Anatidae. In this family, there are several other groupings of birds of the same kind like puddle ducks or diving ducks, and others.
- Species
The species is the most important building section of the entire classification system. A species means that the birds of the same kind can freely breed within each other and their young ones will also be capable of breeding with similar organisms.
Furthermore, there are currently between about 9800 independent species of birds in the world but this number keeps changing constantly. This is because scientists keep discovering new species that were unknown before. This can also mean that they determine that two previously different species were not actually different at all, but just two-color variations of the same kind of species.
Types Of Birds
The whole avian kingdom is divided into 18 orders which are then divided into families, genera and species. Here, you’ll learn what each of these orders mean and the common characteristics members of each order share.
- Passeriformes
These are perching birds. Swallows, Sunbirds, Shrikes, Creepers, etc. are members of this order. There are about 5,700 species in 74 families, although this depends on the authority.
This complicated collection contains more than half of all known bird species; bill, plumage, as well as birds that are highly varied. Most of the Passeriformes are sized small to medium. The length of all these birds ranges between 7 to 125 cm.
Majority of all Passeriformes are insectivores. Fish, grains, fruits are also in the diet of many of its members. Swallows, Sunbirds, Shrikes, Creepers, etc. are members of this order.
- Apodiformes
These are hummingbirds. There are approximately 425 species of these birds in 3 families. Hummingbirds are fast-flying birds that feed in flight on insects or nectar. Their essential flight feathers make up a relatively large proportion of the wing.
However, their feet are weak as they mostly use their wings to travel distances. The length of their bodies as well as the wingspan ranges between 6 to 23 cm.
- Order: Piciformes
These are woodpeckers. There are around 400 species in six families, including jacamars, puffbirds, toucans and others. You can find them globally in forests.
They have outer toes that are able to face backward. This is what makes them special and experienced in climbing. The length of all these birds’ range between 7 to 61 cm.
- Charadriiformes
These are gulls and auks. Plovers, jacanas, and others are among the 370 species in 17 families found worldwide. There are three fundamental body plans to these birds. The shorebirds that feed on tiny individuals in either mud or water.
Bills vary in length but are generally large and used for probing. Laris have webbed feet, similar to ducks. This helps them swim as they find and eat fish by diving into the water. They also find food by stealing it from the mouth of other birds. The length of these birds ranges from 12 to 78 cm.
- Order: Psittaciformes
These are lorikeets and parrots. They are usually tropical with some pleasant-zone species. These birds are typically brilliantly colored and have strong wings for flying.
Lorikeets have very thick and hooked beaks so that they can easily suck nectar. Their outer toes are also pointed backward. The length of their bodies ranges between 8 to 100 cm.
- Order: Falconiformes
These are perpetual birds of prey. There are about 309 species in 5 families, including hawks, falcons, eagles, and condors.
The length of their bodies range between 14 to 150 cm. The wingspan of a condor is over 10 feet. Some fossil forms are bigger which means that the length was even longer in some.
- Galliformes
They are chicken-like birds. There are around 290 species of these birds in five families, including pheasants, guinea fowl, and guans. They are terrestrial and have strong, scratching feet. Their wings are short and rounded.
They even have lengthy aftershafts in their feathers. The length of their bodies ranges from 15 to more than 200 cm.
- Gruiformes
These are cranes. There are around 210 species in 11 families, including rails, coots, and moorhens. It also contains a diverse group, ranging from little quail-like hemipodes to huge long-legged cranes, swimming coots and finfoots, and cursorial bustards.
The length of their bodies ranges between 12 to 176 cm. The carnivorous phororhacoids of the early Cenozoic Era also belong to this order. The fossils form up to about 7 feet tall!
- Procellariiformes
These are seabirds. Their noses are in the shape of a tube and they also have webbed feet. There is a musky odor which comes from the. Most of these birds have narrow wings and rigid, smooth flight.
The length of their bodies range between 13 to 200 cm. The wingspan of albatrosses is more than 3 meters. They can be found in the oceans globally but there is an even larger number in the Southern Hemisphere.
- Coraciiformes
There are approximately 211 species in ten families, including hornbills, bee-eaters, rollers, and motmots. You can find these birds worldwide, except in the far north.
There are also heterogeneous group of birds in this order that build their nests in holes. Many of them have long and pointed bills. The length of their bodies range between 10 to 120 cm.
- Cuculiformes
These are cuckoos. There are about 141 species in two families, including anis, roadrunners, and the hoatzin. One of the species has been extinct since the year 1600. The birds in this order are long-tailed with toes that are either backward or sideward facing.
These birds feed on both fruits and small animals. Most of them are arboreal, but a few are terrestrial. The length of their bodies range between 16 to 76 cm.
- Anseriformes
These are waterfowls. There are approximately 150 various species all around the world. They also have webbed feet and long, broad bills that include fine plates.
There are also large-footed marsh birds in this order. Their bills are almost chicken-like. The length of their bodies ranges between 34 to 180 cm.
- Ciconiiformes
These are herons and storks. You can find about 120 species in six families all around the world in this order. Specific birds such as shoebills, ibises, and bitterns are among these birds.
They are usually found in the far north. These birds have long legs and their bills are long as well. Unlike most birds, their feet are not webbed. The length of their bodies are between 25 to 152 cm.
- Caprimulgiformes
These are pelicans. You can find about 121 species of these birds in five families all over the world. There are specific birds such as frogmouths, potoos, and the oilbird that can be found in this order. Similar to the order of ciconiiformes, these birds can also be found farther up in the north.
They are nocturnal and can camouflage themselves with nature or their surroundings. Their feet are also weak and they have big mouths. Most of them feed on insects captured in flight. The length of their bodies is between 15 to 60 cm.
- Pelecaniformes
These are also pelicans. There are about 66 species of these birds in six families found across the world. Certain birds such as cormorants, gannets, and tropic birds are among them.
You can also find water birds in this order. They have webbed toes on all four of them, and either a hooked or a straight beak. Their bills are also highly pointed. The length of their bodies is between 48 to 188 cm.
- Tinamiformes
These are a special kind of bird called trogons. These birds cannot be found in large numbers as there are only 47 species in one family. You can find ground-dwelling birds in this order that resemble quails or pheasants with flat, stretched, and rather fragile bills.
They even have tiny tails. The length of their bodies vary between 20 to 53 cm. These birds can be found In Central as well as South America.
- Sphenisciformes
These are penguins. They are quite common and can be found in colder regions such as Antarctica. There are about 17 species in one family found in the Southern Hemisphere’s seas. This is somewhat rare compared to the other species.
Penguins have flipper-like wings so that they can easily propel underwater. Their feet are also small and webbed so that they can also swim in water to catch fish. They walk in a firm position and have short and dense feathers that molted in patches. The length there is between 35 to 115 cm. oftentimes, the fossil forms up to even to 180 cm.
- Struthioniformes
These are ostriches and emus. You can find about 10 species of these birds in 6 families. They are usually found in Africa, South America, New Zealand, and Australia where there is an availability of dense forests. The height of their bodies reaches up to 35 cm to 2.7 meters in height. This means that the maximum reaches up to 9 feet!
Many ostriches have tiny tails with no aftershaft or only a little aftershaft. On the other hand, some species have almost no wings. Although, wings are not quite necessary as these birds cannot fly. It is safe to say that the biggest live birds are included in this order.
This classification was a compilation of the information about birds through the recent study by a famous ornithologist called Frank Gill. There are many other orders of birds as well in this compilation.
What Are The Number Of Bird Species In The World?
The research revolving around birds keeps changing and scientists keep discovering more species by the day. So far, there are about 18,000 species of bird in the world, which is twice as many as there were previously. Researchers examine a random sample of about 200 species. Among those 200, they can identify two different species of birds on average.
Many authors suggest that ornithologists undermine the number of biological bird species in the world and that there is possibly a larger number than the researchers depict. Recently, BirdLife International made a discovery of 792 new species of birds among which many other ambiguous species are unknown within the biological species.
Furthermore, the rough estimates for how many taxa are fixed within each bird species are most likely biased. The researchers also didn’t post guidelines for how the species was split so it is not possible to determine if the taxa were split accurately.
The scientists need to be able to identify the species in the field to practice conservation and to do that, they will need special tools. The current tools available cannot sort all the wild birds into the taxa based on the genetic differences. Moreover, a whole population is not constant as there are variations in either color or species within any biological species so the taxa are not stable.
That variation is blended and redistributed through mating so it is not necessary that the current differences we notice on birds are fully due to evolution. However, there are other related theories behind figuring out the number of bird species that exist in the world.
The Natural History Of Birds
Just like any other animal, birds have a natural history too. While some specific birds have a different and ancient history, some birds simply existed from the period of evolution. Down below, this article will talk about their history of locomotion, flight, why some birds cannot fly, and about their certain movements such as walking and swimming.
- Locomotion
Birds are naturally the best swimmers due to their feather-covered bodies and bony structure. Although, as you may know, some birds such as penguins can’t fly even though they have flaps. Ostriches also have primitive wings but it is of no use because the most they can do is walk.
Birds usually fly when they have a considerable distance to cover, although there are exceptions in this case as well. Some birds such as the mountain quail of California even migrate by walking even though they have wings. They start their journey before the young ones have grown their ability to fly and before some of the adults have molted.
- Flight
Most naturally, birds fly by flapping their wings and changing directions according to the wind with the help of their tails. Quite interestingly, a bird’s wing has many adjustable features such as it can be shortened or heightened by flexion. The feathers at the tip can also spread or close according to their preference or the environment.
The types of flight vary greatly in birds. The modifications of their wings have something to do with the wind. Birds like albatrosses have long and narrow wings that make it easy for them to maneuver in the ocean wind. Songbirds, on the other hand, have short and rounded wings to help them fly quickly from perch to ground or perch to perch. Tails are also related to their flight as it enables them to quickly change their direction on air.
- Lightlessness
Through evolution, some birds have completely lost their ability to fly. Flightless birds have a secondary special condition which is their rudimentary wings. You can mostly notice this loss of flight in birds living on remote islands with no mammalian predators. This is because they’re not in danger of any other animal chasing them so they don’t need to fly all the time to be alert.
Moreover, these birds are usually big in size which helps them escape from their predators, if there are any, so they don’t really need to fly.
- Walking And Hopping
As some birds shifted from trees to the ground, their legs modified according to the change. The leg bones of large and slow-moving birds became very heavy and the toes became even shorter. On the contrary, the toes of birds that walk on softer grounds became longer.
Many birds that fly also walk or climb up and down trees to keep their legs functioning. Small birds such as swifts only use their legs for perching and rarely for walking whereas songbirds both hop and walk as well as fly! The position of birds when they’re walking is usually parallel to the ground.
- Swimming
Some birds such as auks, use their wings for both flying and propelling under the water. Similarly, the wings of penguins have had significant modifications so that they can use them underwater, and the webs in their feet help them steer in water. Basically, swimming in birds is related to their webbed feet.
However, some birds with no webs or lobes in their feet also swim and some birds with webs in their feet don’t swim at all. Certain birds only swim at the surface as they cannot go under the water. Whereas other birds such as certain ducks, swim to the bottom of the water to get their food.
The Origin And Evolution Of Birds
It might surprise you to know that birds actually evolved from the small carnivorous dinosaurs from the Late Jurassic! Although their diversity and evolution were a mystery for a long time, there is a clear explanation about this that has existed over the last two decades through proper research of new fossil discoveries.
Research conducted in the late 1900s suggests that birds are theropod dinosaurs, with the discovery of feather conservation in non-avian theropods, providing the final piece of evidence for this group’s dinosaur origin. The publication of more phylogenetic analyses of non-avian theropod dinosaurs is greater than any other group of fossil vertebrates. This led to a greater interest in the origin of birds.
Thus, based on the similarity of features between birds and theropods, scientists came to the conclusion that perhaps they were the ancestors of birds. After the construction of evolutionary trees made to investigate the issue, paleontologists were even more convinced that the research is in fact, correct. So, it is safe to say that the birds are just a twig on the dinosaurs’ branch of the evolutionary tree.
Many of theropod dinosaurs’ traits had alterations during the period of birds’ evolution. It’s important to keep in mind that the animals were not “trying” to evolve into birds in any way. It is very evident that the set of characteristics that distinguish birds emerged through a complex series of processes and served various functions along the way.
Another line of evidence comes from alterations in dinosaur digits that led to the evolution of birds. The first and second digits’ wrist bones solidified and took on a semicircular shape. This allowed the hand to spin sideways against the forearm and so, the birds’ wing joints were eventually able to move in a way that created a nudge for flying.
Thus, birds still evolved in some of the same paths as their theropod relatives. There was an improvement in their flight efficiency as well as many of their bone walls became thinner and better integrated together. In addition, their feathers also became longer. However, there are other related approaches as to where birds came from which will intrigue you to learn more about them.
Birds are a very exquisite species of animals and with proper care, they will exist for many more years to come.
Scientists and ornithologists are constantly researching them so that there is no underestimation in determining the number of species. It also helps to keep track so that they’re not at the risk of going extinct.
