The Bird-Conjuring Charm - 3rd-level Transfiguration
Casting Time: 1 action
Range: 60 feet
Duration: Concentration, up to 1 hour

You conjure either a Swarm of Small Birds or two Swarms of Tiny Birds that are a species of your choice. The swarm disappears when it drops to 0 hit points or when the spell ends. The conjured birds are friendly to you and your companions. Roll initiative for the summoned swarms as a group, which has its own turns. They obey any verbal commands that you issue to them (no action required by you). If you don't issue any commands to them, they defend themselves from hostile creatures, but otherwise take no actions.

The HM has the creatures' statistics.

At Higher Levels. When you cast this spell using certain higher-level spell slots, more creatures appear - twice as many with a 5th-level slot, three times as many with a 7th level slot, and four times as many with a 9th-level slot.