What are Anseres? A Guide to the Waterfowl Order
If you are a bird lover, you may have heard of the term anseres, but what does it mean? Anseres is a scientific name for a group of birds that includes ducks, geese, swans, and their relatives. They belong to the order Anseriformes, which is one of the oldest and most diverse groups of birds in the world.
In this article, we will explore the characteristics, evolution, and diversity of anseres, and learn some interesting facts about these amazing waterfowl.
Characteristics of Anseres
Anseres are mostly aquatic birds that have webbed feet, waterproof feathers, and a bill adapted for filtering or grasping food. They range in size from the tiny pygmy goose (Nettapus coromandelianus) that weighs only 260 grams, to the huge mute swan (Cygnus olor) that can reach 12 kilograms. They also vary in color, shape, and behavior, but they share some common features:
- They have a high metabolic rate and a four-chambered heart that allows them to maintain a constant body temperature.
- They have a complex vocal system and communicate with each other using various calls and sounds.
- They have a well-developed sense of sight and can see in color and ultraviolet light.
- They have a unique reproductive system that includes a penis in males and a cloaca in both sexes. They also practice various mating strategies, such as monogamy, polygamy, or promiscuity.
- They are highly social and form flocks or pairs that can last for years. They also show parental care and often cooperate in raising their young.
Evolution of Anseres
Anseres are one of the oldest groups of modern birds, dating back to the Cretaceous period, about 66 million years ago. They are closely related to another ancient group of birds, the Galliformes (chickens, turkeys, etc.), and together they form the clade Galloanserae.
The earliest known anseriform fossil is Vegavis, a goose-like bird that lived in Antarctica. It is also one of the few birds that survived the mass extinction event that wiped out most of the dinosaurs.
After the extinction event, anseres diversified into many different lineages and adapted to various habitats and climates. Some of the most notable extinct groups of anseres are:
- The presbyornithids, which were long-legged wading birds that resembled flamingos or ibises. They were the ancestors of ducks, geese, swans, and screamers.
- The pseudotooth birds, which were large seabirds that had bony projections on their jaws instead of teeth. They were similar to albatrosses or pelicans and could reach wingspans of up to 6 meters.
- The gastornithids and mihirungs, which were giant flightless birds that lived on land. They had massive skulls and beaks and could weigh up to 500 kilograms. They were herbivorous or omnivorous and probably competed with mammals for food.
Diversity of Anseres
Today, there are about 180 living species of anseres in three families: Anhimidae (screamers), Anseranatidae (magpie goose), and Anatidae (ducks, geese, swans). Each family has its own distinctive features and adaptations:
- Anhimidae: This family contains only three species of screamers: the horned screamer (Anhima cornuta), the southern screamer (Chauna torquata), and the northern screamer (Chauna chavaria). They are large birds with long necks and legs that live in wetlands and grasslands in South America. They have spurs on their