A badelynge is a collective noun for ducks on the ground, but it has no other known meaning in English that I can find. Badelynge is listed as a collective noun for ducks (sometimes Mallards) on the ground in many sites that list collective noun names:
And just in case you think someone made it up recently, here is a 19th century field guide from England that references the term badelynge as a group noun:
The Shot Gun and Sporting Rifle - And the Dogs, Ponies, Ferrets, etc. Used with Them in the Various Kinds of Shooting and Trapping, by John Henry Walsh, London, England, 1862.
The term badelynge does not appear in most dictionaries as dictionaries often don't list collective noun definitions save for the most prevalent cases. For example, you often do not see "collective noun for swans" listed among the definitions of "bank," nor "boys" under "blush," nor "girls" under "giggle."
As dictionaries so often don't list them, finding a glossary of group nouns at one point vexed me. That was until I found the following:
As it is Wikipedia, so anyone can make up any old thing they want, I've made it a point to verify any word I wish to adopt through other sources, just as you find I did with badelynge. Nevertheless, it remains a good starting point, a good place to begin a search for a group noun.