Hedgehogs are mentioned several times in the How to Train Your Dragon Book series.
Hedgehogs are small mammals known for their prickly spines along their backs, sides, and the top of their head. They are members of the Sub Family Erinaceinae. Hedgehog species occur naturally in Europe, Asia, and Africa. They have been introduced elsewhere, such as New Zealand and are considered an invasive pest.
Hedgehogs can roll in a defensive ball, hiding their vulnerable faces and bellies, and presenting the prickly spines to a would-be predator. Despite that, Hedgehogs do get preyed upon by some Birds of Prey such as the Eagle-Owl, and also some land carnivores such as badgers.
Historic Vikings most likely encountered the European Hedgehog (Erinaceus europaeus).
Hedgehogs have a varied omnivorous diet, tending more toward insectivory. They do consume plant material including Grass roots, Mushrooms, and berries. They eat many types of invertebrates such as a variety of insects like beetles and caterpillars, as well as other invertebrates like earthworms. Hedgehogs also eat some vertebrate animals like bird eggs, frogs, and even carrion.
In the Book series, hedgehogs are mentions typically to describe something prickly.
In reality, hedgehogs can be kept as pets. There are a number of cultures that eat them, and also consider various hedgehog parts or the hedgehog itself to have medicinal value for many things, ranging from treatment of ringworm to warding off witchcraft.
At the beginning of Book 3, a description of Gobber the Belch is given. This includes his beard, "a beard like a hedgehog struck by lightning."
In Book 4, hedgehogs are used to describe Fishleg's ability with the bow-and-arrow.
|“||His ski poles flailed around frantically; his arrows flew out of their quiver like a hedgehog shedding needles.||”|
|— Book 4|
|“||The SOUND it made was unutterably awful, a sadness so extreme it made you want to weep yourself, a sound that crept up the spine like spiders' feet, and scuttled over the scalp, sending each individual hair on Hiccup's head prickling upward like the spines on a hedgehog.||”|
|— Book 4|