The collective noun for ducklings is a brood. Flock, raft, and team are the other collective nouns for ducklings.

The collective noun for mosquitoes is a scourge. Cloud, swarm, and horde are the other collective nouns for mosquitoes.

The collective noun for yaks is herd. Drove, gang, and trip are the other collective nouns for yaks.

The collective noun for ravens is a murder. Unkindness, storytelling, and conspiracy are the other collective nouns for ravens.

The collective noun for rats is pack. Colony, horde, mischief, and plague are the other collective nouns for rats.

The collective noun for greyhounds is a leash. Pack, team, and race are the other collective nouns for greyhounds.