Passerine

Many birds are perching birds.

They have special toes. Three toes point forward. One toe points back. This helps them sit on branches.

When a bird lands, a part of its leg pulls tight. This makes the foot curl. It stays stiff on the branch. This helps them sleep without falling off.

Most of these birds are small. Some eat bugs or seeds. They also eat fruit.

Baby birds are born very weak. They have no feathers. They cannot see yet. Parents must take care of them.

These birds come in many kinds. Some can sing beautiful songs. Others can copy sounds they hear.

Passerines are a huge group of birds. They make up 60% of all bird species.

These birds are often called perching birds. This is because of how their feet work. They have an anisodactyl arrangement. This means they have three toes pointing forward and one pointing back.

This foot shape helps them sit on branches. A special tendon in the leg helps even more. When the bird bends its leg, the tendon pulls tight. This makes the foot curl and stay stiff. It lets them sleep on a branch without falling off.

Most passerines are small. However, the common raven is quite large. Some birds are very tiny. The short-tailed pygmy tyrant is the smallest.

Many of these birds are songbirds. They use muscles to make beautiful music. Some birds, like the lyrebird, can mimic sounds.

Baby passerines are born very helpless. They are born without feathers and cannot see. Their parents must stay close to care for them.

Passerines are a massive group of birds. They make up about 60% of all bird species on Earth.

This group is called Passeriformes. The name comes from the Latin word for sparrow. There are over 6,500 different species in this order. They belong to more than 140 different families. This makes them one of the most diverse groups of land animals.

These birds are often called perching birds because of their feet. They have an anisodactyl arrangement. This means they have three toes pointing forward and one toe pointing back.

This foot shape helps them grip branches easily. A special tendon in the leg works like a built-in lock. When the bird bends its leg, the tendon pulls tight. This makes the foot curl and stay stiff. It allows them to sleep on a branch without falling off.

Scientists believe passerines first appeared around 60 million years ago. They likely started in the Southern Hemisphere.

As the southern continents moved apart, the birds spread out. The New Zealand wrens were among the first to become isolated. Later, a major group called the Passeri moved into Australia. About 40 million years ago, another group moved into Eurasia and Africa. This history helped create the many different birds we see today.

Passerines come in many different sizes. Most are much smaller than other types of birds. The short-tailed pygmy tyrant is the smallest at only 6.7 centimeters long.

On the other hand, the common raven is quite large. The thick-billed raven can weigh over 1,500 grams. Some birds have very long tails. The superb lyrebird has 16 tail feathers. The long-tailed widowbird also uses a long tail as an ornament.

Many passerines are famous for their voices. Songbirds use special muscles to control their syrinx. This organ helps them make complex songs.

Some birds are even great mimics. The lyrebird can copy many different sounds. Most passerines eat insects or seeds and fruit. Their babies are born very helpless. They are born without feathers and cannot see. Because of this, parents must work hard to care for them.

Passerines are members of the order Passeriformes, a massive group of birds. This order includes more than half of all bird species on Earth.

There are over 6,500 identified species across more than 140 families. This makes Passeriformes one of the largest bird orders. It is also one of the most diverse groups of terrestrial vertebrates. Most passerines make up about 60% of all birds. The name comes from the Latin word for sparrow, specifically from the house sparrow, *Passer domesticus*.

The most famous feature of these birds is their ability to perch. They possess an anisodactyl arrangement of their toes. This means they have three toes pointing forward and one toe, called the hallux, pointing backward. The hallux is long and joins the leg at nearly the same level as the front toes.

To help them stay on branches, they have a special anatomical adaptation. A tendon runs from the underside of the toes to the muscle behind the tibiotarsus. When the bird bends its leg, this tendon automatically pulls tight. This causes the foot to curl and become stiff. This mechanism allows them to sleep while perching without falling off.

Passerines are categorized into three main suborders based on their evolutionary history. The first is the New Zealand wrens, which are tiny birds restricted to New Zealand. The second is the Tyranni, also known as suboscines. These are primarily found in North and South America and are often called non-singing birds. The third suborder is the Passeri, which includes the songbirds.

Within the Passeri, there are two major groups: the Corvides and the Passerida. The oscines, or songbirds, have the best control over their syrinx muscles. The syrinx is the vocal organ of birds. This control allows them to produce complex songs. Some, like the lyrebird, are even famous for being accomplished mimics.

The evolutionary history of these birds began in the Southern Hemisphere. Scientists believe they originated around 60 million years ago. Their diversification happened as the southern continents separated during the early Eocene. The New Zealand wrens were the first to become isolated in Zealandia. Later, the Tyranni originated in South America, while the Passeri emerged in Australia.

About 40 million years ago, the parvorder Passerida dispersed into Eurasia and Africa. This movement led to a massive radiation of new lineages. Today, the three major Passerida lineages include about 4,000 species.

Passerines vary greatly in size and physical form. Most are smaller than birds in other orders. The smallest is the short-tailed pygmy tyrant, measuring only 6.7 cm long and 1.8 g.

In contrast, the thick-billed raven can exceed 1,500 g. Some birds are defined by their tails. Most passerines have 12 tail feathers, but the superb lyrebird has 16.

Other species, like the long-tailed widowbird, use extremely long tails as sexual ornaments. Some birds, such as treecreepers, have stiff tail feathers used as props for climbing tree trunks.

Reproduction in passerines involves significant parental investment. Most chicks are altricial, meaning they are born blind, featherless, and helpless. Because of this, they require extensive care from their parents. Most passerines lay colored eggs, which differs from many nonpasserines that lay white eggs. Clutches vary in size based on environment and species. Australian lyrebirds may lay only one egg. In the Northern Hemisphere, hole-nesting species like tits can lay up to a dozen eggs.

Some species, like those in the family Viduidae, are brood parasites. They do not build their own nests but lay eggs in the nests of other birds.

Understanding passerines helps scientists study how biology and environment interact. For example, research shows that nest construction is a complex task. Building nests with different attachment modes requires different levels of cognitive ability. Furthermore, the fossil record helps clarify how species move across the globe. While small bones do not always preserve well, fossils like *Wieslochia* from the Oligocene provide clues.

These findings show how birds expanded from their origins to inhabit almost every corner of the world.