Larus

Many birds are called seagulls.

These birds live all over the world. Most live in the north. They are medium or large birds. Most have grey or black feathers on top. They have white feathers on their heads and bellies. They have long bills and feet with skin between their toes.

Young birds are brown. It takes a few years to grow adult feathers. These birds have lived for a very long time. Fossils show they were around millions of years ago. They are amazing birds to see.

Larus is a large group of gulls.

Many people call these birds seagulls. They live all over the world. Most live in the Northern Hemisphere. Most are medium or large birds. They often have grey or black feathers on top. Their heads and bellies are white. Some have black spots on their wings. These spots are called mirrors. They have long bills and webbed feet. This means they have skin between their toes.

Young gulls are brown. It takes three to five years to grow adult feathers.

Scientists found fossils of these gulls. These fossils are very old. They date back 20 to 15 million years. These birds likely began in the north Atlantic. Then they spread across the globe.

Some gulls form a ring around the North Pole. This is called a ring species. In this group, different gulls can breed with each other. They form a chain of birds around the pole. One group meets another group on the other side. However, new studies show this is very complex. Scientists are still learning how these birds are related.

Larus is a large group of gulls found all over the world.

Most of these birds live in the Northern Hemisphere. Many people call these birds seagulls in their daily lives. They are usually medium to large birds with very distinct looks. Most have pale grey or black feathers on their backs. Their heads and bellies are usually white. You might see black markings with white spots on their wingtips. These white spots are often called mirrors.

These birds have specific bodies that help them live. They have stout, longish bills for finding food. Their feet are webbed, which helps them move in water. In the winter, their heads might look dark or streaked. Young gulls look very different from their parents. They are brown instead of grey or white. It takes three to five years to grow adult feathers. They pass through a middle stage of feathers before they are adults.

Scientists have studied these birds for a very long time. A Swedish naturalist named Carl Linnaeus named this group in 1758. He did this in his book called Systema Naturae. The name Larus comes from Ancient Greek or Latin words. These old words likely meant a gull or a large seabird. The type species for this group is the great black-backed gull. Its scientific name is Larus marinus, which means sea gull.

We can learn about the past through fossils. Fossils of Larus gulls date back 20 to 15 million years. These fossils come from the Middle Miocene time period. Scientists think these birds started in the northern Atlantic ocean. They likely spread across the whole world during the Pliocene. This was a time when there were many different kinds of these birds. Some fossils were found in places like Austria and Romania. Others were found in the southeastern United States.

Some gulls form a special pattern around the North Pole. This is often called a ring species. In this group, different gulls can breed with neighbors. For example, the European herring gull can breed with the American herring gull. These birds form a chain that goes all the way around. However, the gulls at the very ends of the chain are different. They rarely breed with each other in places like Europe.

Recent studies show this relationship is actually very complicated. Scientists are still studying how these birds are related to each other.

The genus *Larus* represents a large group of gulls found across the entire globe.

While they live everywhere, the highest diversity of species is found in the Northern Hemisphere. Many of these birds are common and well-known in their specific ranges. Most people colloquially refer to these birds as "seagulls." Historically, scientists placed almost all gulls into this single genus. However, research between 2005 and 2007 changed this classification. Scientists discovered that the old arrangement was polyphyletic. This means the group did not share a single common ancestor. Because of this, several other genera were resurrected. These include *Chroicocephalus*, *Ichthyaetus*, *Hydrocoloeus*, and *Leucophaeus*.

Physically, members of *Larus* are generally medium to large birds. Most species display a pattern of pale grey or black on their upper parts. Their undersides and heads are typically white. Many gulls also feature black markings on their wingtips. These markings often include small white spots known as "mirrors." Some species also possess black markings on their tails. These birds possess stout, longish bills and webbed feet. Their appearance can change depending on the season. In winter, the head feathers are often streaked or smudged with dark grey. Young birds look quite different from adults. They are brown and require three to five years to reach adult plumage. They pass through subadult plumages that look intermediate between the young and adult stages.

The history of this genus begins with the Swedish naturalist Carl Linnaeus. He introduced the genus *Larus* in 1758. He published this in the tenth edition of his work, *Systema Naturae*. The name is derived from the Ancient Greek *laros* or the Latin *larus*. These terms likely referred to a gull or another large seabird. The type species for the genus is the great black-backed gull, *Larus marinus*. This specific name translates to "sea gull."

Scientists continue to study the taxonomy of these birds. For example, the taxonomy of the herring and lesser black-backed gull complex is very complicated. Depending on the authority, this group may be recognized as two species or as many as eight species.

We can learn about the history of *Larus* through the fossil record. Fossils of these gulls are known from the Middle Miocene epoch. This period occurred about 20 to 15 million years ago. Scientists generally reject the idea that earlier fossils belong to this genus. Biogeography suggests that the genus evolved in the northern Atlantic. During the Pliocene, the gulls spread globally. This was a time when species diversity appeared to be at its highest. Fossil evidence has been found in several locations. These include Grund, Austria, and Romania. Other fossils have been discovered in the southeastern United States. Examples include *Larus elmorei* from the Middle Pliocene of Bone Valley. Other species like *Larus lacus* and *Larus perpetuus* also come from the Pliocene of the southeastern U.S.

One of the most famous biological concepts involves these gulls. The circumpolar group of *Larus* species is often cited as a classic example of a ring species.

In this model, the ranges of the gulls form a ring around the North Pole. The birds form a chain of interbreeding populations. For instance, the European herring gull can hybridize with the American herring gull. The American herring gull can then breed with the Vega gull. The Vega gull can interbreed with Heuglin's gull. Heuglin's gull can then breed with the Siberian lesser black-backed gull. This last bird is the eastern representative of the lesser black-backed gulls. This chain eventually leads back to northwestern Europe.

Despite this chain, the ring does not close perfectly. The lesser black-backed gulls and the herring gulls are sufficiently different. Because of these differences, they rarely interbreed where their ranges meet in Europe. This creates a continuum of species that eventually separates. This pattern was long used to explain how new species form. However, recent genetic studies have added complexity to this idea. These studies suggest that the ring species model may not be as simple as once thought. Scientists are still working to understand the true genetic relationships within this group.

Understanding *Larus* helps scientists study evolution and biogeography. The way these birds spread from the northern Atlantic tells us about ancient ocean patterns. The way they change plumage over several years shows how they adapt to life cycles. Even the complicated taxonomy of the herring gull complex shows how much we are still learning. As genetic tools improve, our map of the gull family tree continues to change. This makes the genus *Larus* a vital subject for studying how life moves and changes across the planet.