Anser (bird)

These birds are geese.

Some geese are white. Some geese are grey.

They have pink or orange feet. Their bills can be black too. Some have white on their heads.

These birds live in wet places. In the summer, they stay in cool lands. In the winter, they fly to warmer spots.

There are 11 kinds of these geese. They are very special birds!

The genus *Anser* is a group of 11 living geese.

These birds live in wet areas. Many live in the cool north. In summer, they stay in subarctic lands. In winter, they fly south. They move to warmer places.

These geese come in many shapes and sizes. Some are very large. The bean goose is one of the biggest. Other geese are quite small.

Most have pink or orange feet. Their bills can be black or orange. Their bodies are often grey or white. Many have black feathers on their wings.

Humans work with these birds too. People have made domestic geese. These are birds kept on farms. Some come from the greylag goose. Others come from the swan goose. We must help protect some kinds. The emperor goose is near-threatened. The swan goose is also vulnerable. This means they need our care.

The genus *Anser* is a group of 11 living species of geese. These birds are part of a larger group called waterfowl. They include both grey geese and white geese. Most of these birds live in the Northern Hemisphere. They like open and wet places to live. You can find them in subarctic and cool temperate regions during the summer. Some species even live in warmer temperate areas.

Many *Anser* geese follow a seasonal pattern. They breed in northern lands during the summer months. When winter comes, they migrate south to find warmer weather. They usually fly to places where the temperature stays between 0 °C and 5 °C. This movement helps them stay in better conditions. Their bodies are built for these long trips. They use their wings to travel great distances each year.

Scientists have studied these birds for a long time. A French zoologist named Mathurin Jacques Brisson introduced the name *Anser* in 1760. The name comes from the Latin word for goose. It was based on the greylag goose. That bird was first named by Linnaeus in 1758. Learning about their history helps us understand how they are related. Scientists even use DNA to see how they evolved.

These geese come in many different sizes and colors. The bean, greylag, and swan geese are among the largest. On the other hand, the Ross's goose and lesser white-fronted goose are quite small. Most have pink or orange legs and feet. Their bills can be black, pink, or orange. Many have grey or white bodies with black feathers on their wings.

Humans have a long history with these birds. Some geese have been domesticated to live on farms as poultry. European farm geese come from the greylag goose. Chinese farm geese come from the swan goose.

We must also work to protect them. The swan goose and lesser white-fronted goose are listed as vulnerable. The emperor goose is also near-threatened. Protecting their homes helps these species stay healthy.

The genus *Anser* represents a diverse group of waterfowl found throughout the Northern Hemisphere. These birds are classified within the subfamily Anserinae, which includes true geese and swans. They belong to the broader family known as Anatidae. The genus is characterized by a Holarctic distribution, meaning they inhabit many parts of the northern regions. Most species thrive in open, wet habitats during the subarctic and cool temperate summers. Some species extend their breeding grounds further south into warmer temperate zones.

To survive changing seasons, many *Anser* species follow a strict migratory pattern. They typically breed in northern latitudes during the summer months. When winter approaches, they migrate toward more temperate regions. They often seek areas where the temperature stays between 0 °C and 5 °C. This movement ensures they remain in environments suitable for their survival. Their physiological adaptations allow them to navigate these vast distances annually.

Physically, the species within *Anser* exhibit a wide range of sizes and appearances. The largest members include the bean goose, the greylag goose, and the swan goose. These larger birds can reach significant weights, though domestic versions are often much heavier. Conversely, the Ross's goose and the lesser white-fronted goose are among the smallest. Most species possess pink or orange legs and feet. Their bills may be black, pink, or orange, or a combination of these colors.

Most have grey or white bodies with black primary feathers on their wings.

Taxonomy and the history of the genus have undergone several important changes. The name *Anser* was introduced by the French zoologist Mathurin Jacques Brisson in 1760. The term is derived from the Latin word for goose. It was established using the greylag goose as the type species.

Previously, the "white geese" like the snow goose were placed in a separate genus called *Chen*. However, scientists now include them in *Anser* to maintain correct evolutionary groupings. This ensures the genus is not paraphyletic, which would happen if the bar-headed goose were excluded.

Understanding the evolutionary relationships of these birds has been a complex scientific challenge. This difficulty arises because of rapid radiation during the Pleistocene epoch and frequent hybridization. In 2016, a study by Ottenburghs and colleagues used exonic DNA sequences to map these relationships. Their work helped clarify how different species are connected through their genetic history. A follow-up study in 2023 further refined the details of the bean goose complex. This research revealed that the pink-footed goose is most closely related to the taiga bean goose. This was a significant finding, as it changed the previous belief that it was closer to the tundra bean goose.

Humans have interacted with *Anser* geese for many centuries, particularly through domestication. Two species have been specifically raised as poultry for commercial use. European domestic geese are descended from the greylag goose.

Meanwhile, Chinese and some African domestic geese are descended from the swan goose. While many species have benefited from hunting protections since the 19th century, others face modern risks. Habitat loss and over-hunting remain serious concerns for certain populations.

Conservation status varies significantly across the eleven living species. While many are not considered threatened, some require urgent attention. The lesser white-fronted goose and the swan goose are both listed as Vulnerable. Additionally, the emperor goose is classified as near-threatened. In some regions, large flocks of geese can cause conflicts with farmers by grazing on crops during the winter. Monitoring these populations is vital for maintaining the biodiversity of northern wetland ecosystems.