Can you mix Hunter and Rain Bird?

Yes, you can mix Hunter and Rain Bird sprinkler components in same irrigation system, and many systems do, as they use standard pipe threads and similar operating pressures, making them compatible, though best practice is to keep same type of heads within same zone for matched precipitation rates. You can mix Hunter and Rain Bird heads, valves, and controllers together, for example using Hunter controller with Rain Bird valves or Rain Bird heads, because they operate on same 24 volt system and 1/2 and 3/4 inch threads are standard. However, you should not mix different types of heads like spray heads and rotor heads on same zone because they have different precipitation rates, causing over and underwatering, but mixing brands of same type is fine, such as Hunter MP Rotator and Rain Bird rotary nozzles both are rotators with similar precipitation if matched. Many professionals mix brands to use best of each, like Hunter controller with Rain Bird 5000 rotors. So mixing Hunter and Rain Bird is allowed and common, just ensure matched precipitation within zone and compatible pressure.