"Kennings started off in Old English and Norse poetry where something is described without using its name, for example, stick fetcher = dog. Anglo Saxons (and Vikings) often used kennings to name their swords: Throat slitter. So, a poem made from kennings would be a list of expressions about one subject. More often than not each item on [the] list is made up of two words."
The Works, 2000, MacMillan Children's Books
Woodpeckers wrote kennings about themselves or their lives, following the rules of using a noun + a verb or a noun + a noun, joined by a hyphen.
Here are Henry and Nathan's kennings.