There are two species of turkeys (Genus Meleagris) living to day: the Ocellated Turkey Meleagris ocellata and the more well-known Wild Turkey (Meleagris gallopavo). It is the latter species from which all domesticated breeds descended from.
The Wild Turkey is a large bird that can fly, but not for any sustained amount of time. It moves about mostly on the ground by walking. They have plumage that is varying shades of brown, allowing a certain amount of camouflage in the environments they live in. Domesticated breeds can come in other colors, such as white. Males are generally larger than females. Both sexes have bald heads similar to a vulture. The exposed skin can be red or a bluish color. Males have an additional flap of skin hanging from their beak called a 'snood'.
Turkeys are only native to North and Central America. Historic Vikings would not have encountered these birds.
In reality and in the Book series, a turkey's primary use for humans is as food. Dragons - specifically Toothless - are seen eating turkey as well.
Their feathers can also be used for garment ornamentation, ceremonies, or decorations. The turkey is also a popular symbol for the Thanksgiving holiday in the United States.
Turkey dishes are mentioned as part of the Freya'sday Eve feast in the Hysteric Tribe Great Hall. Toothless gorges on the food, ignoring Hiccup's frustrated orders to focus on getting him out of a cage rather than eating.
|“||Toothless pretended to be quite deaf, and took his time hopping from plate to plate, gorging himself on deep-fried mackerel, turkey wings, and sweetcorn fritters.||”|
|— Book 4|
Later, Hiccup uses "a gigantic half-eaten TURKEY carcass, and shoved it over the head of the closest Warrior" during the escape from the Hysteric Great Hall.