A swan and a goose may seem strikingly similar at first sight. Both the water birds are members of the family Anatidae, and subfamily, Anserinae. Both have webbed feet that help them thrust forward while swimming.
Interestingly, both the swan and the goose evolved out of ducks approximately 30 million years ago. Approximately 12 million years ago, swans and geese split off from each other and evolved separately. They further developed subspecies, which can be identified by their unique physical characteristics.
Swan vs Goose
The main difference between swan and goose is that swans tend to be larger in body length, wingspan, and weight than geese in most cases. The Tundra swan, Bewick’s swan, and Canada geese are exceptions to this general rule of thumb.
Swans also tend to have longer and thinner necks with a visible S-shaped curve. On the contrary, geese have short and thick necks that are straight. Although smaller in size than a swan, a goose typically, has longer legs than the latter.
Comparison Table Between Swan and Goose
| Parameters of comparison | Swan | Goose |
|---|---|---|
| Classification | 7 species (out of which one is extinct) under the single genus, Cygnus. | 22 species under 3 different genera. |
| Size | Larger body length, wingspan, and weight than geese (Bewick’s swan and Tundra swan are exceptions) | Smaller body length, wingspan, and weight than swans (Canada goose is an exception) |
| Appearance | Long and thin necks with a visible S-shaped curve. | Short, thick, and straight necks, but longer legs than swans. |
| Colour | White or white with some black spots or completely black on rare instances. | Blackish, grey, or brown with white marks on belly and tail. |
| Habitat | Found mostly in a cold or temperate climate, except in Antarctica. | Only found in Northern Hemisphere, North America, Asia, and Europe. |
| Diet | Aquatic vegetation, mollusks, small fish, frogs, worms, small grass from land (swans browse for food, more in water than on land) | Grass, stems, roots, leaves, shoots, stems, bulbs, grain, and berries as well as small insects (geese browse for food, more on land than in water) |
| Population | Between 1.5-1.6 million birds under 7 species | More than 5 million Canada geese, more than 15 million Snow geese, approx. 2 million Ross’s geese, approx. 850,000 bean geese and so on. |
| Predators | Less number of predators due to large size | More number of predators due to small size |
| Lifespan | Approximately 20-30 years | 10-12 years in the wild and more than 30 years in captivity |
What is Swan?
A swan is a large waterbird with a long thin neck, webbed feet, broad bill, and short legs. It may be fully white in colour, white in colour with a few black spots, or in rare cases, completely black. Swans have a jagged bill that acts as teeth for catching and eating fish.
Swans belong to the Anatidae family under the genus, Cygnus. These birds evolved out of ducks to form 7 species, out of which one faced extinction. A species, namely the Coscoroba swan also exists, but is not considered to be a ‘true swan’.
Swans are generally found in a cold or temperate climate. Several species of these waterfowl are either partly, or wholly migratory.
A swan is known to mate for life. These birds are known to be very protective of their nests and show intraspecific aggressive behaviour on facing any kind of threat. Swans have very few predators by dint of their large size. Foxes, coyotes, raccoons, and wolves hunt eggs and sometimes on adults.
What is Goose?
The term ‘goose’ is used for females, while ‘gander’ for males. Geese are large-bodied waterfowl but have a comparatively shorter neck, smaller size, and lesser weight than a swan. They are known to be either blackish, grey, or brown in colour, having small white patches on their belly and tail. They have webbed feet and a short, broad bill.
Like swans, geese are members of the Anatidae family and Anserinae subfamily. They evolved out of ducks to form 22 subspecies under 3 different genera.
Geese are monogamous and mate for life. Unlike swans, geese tend to be very social. Due to their smaller size, they are more prone to be attacked by predators like coyotes, wolves, and large raptors.
Though docile in most cases, these birds can be quite aggressive sometimes. They vibrate their necks and charge towards the enemy when threatened.
Conclusion
Since swans and geese evolved out of the same bird, it can be quite difficult to tell the two apart. The easiest way is to check for appearance, colour, and size. A swan will have a longer and thinner neck, shorter legs, and a bulkier body.
Swans tend to be less social and more aggressive than geese. Due to this, they are harder for predators to hunt. Interestingly, the population of swans is quite less when compared to geese, despite their large heavy body, aggressive anti-social behaviour, and longer lifespan. This might be because of excessive hunting and poaching of swans by humans.
References
- https://www.cambridge.org/core/journals/behavioral-and-brain-sciences/article/is-erdelyis-swan-a-goose/11B332255E542A22CFB921AB08A17E00
- https://www.tandfonline.com/doi/pdf/10.1080/0015587X.1944.9717717