Page "Tundra Swan" Paragraph 24

In summer, their diet consists mainly of aquatic vegetation – e. g. mannagrass ( Glyceria ), Potamogeton pondweeds and marine eelgrass ( Zostera ), acquired by sticking the head underwater or upending while swimming ; they also eat some grass growing on dry land.

At other times of year, leftover grains and other crops such as potatoes, picked up in open fields after harvest, make up much of their diet.

Tundra Swans forage mainly by day.

In the breeding season, they tend to be territorial and are aggressive to many animals who pass by ; outside the breeding season they are rather gregarious birds.