Bobolink used in a sentence

Bobolink in a sentence as a noun

If, as you seem to say English is decided by usage, then the idea that there is a 'correct' term for a group of bobolinks beyond 'group' is just a fun fiction. As far as I'm concerned, you're free to describe a group of animals using whatever word conveys the experience best, and since, as you say English lacks a governing council, nobody should worry about using the 'correct' term of venery.