While I believe that real essential oil diffusers are necessary for serious and life-threatening illnesses in birds, I have been having good results for day to day problems using a kleenex attached to the outside of the cage/aviary with a clothespin:) I cover the enclosure with towels or tarps to make a tent that will keep the EOs from escaping too fast, and then I soak down the kleenex with five or six drops of EOs. It seems to work very similarly to the mechanical diffusers but it's so much quicker and easier to use a kleenex! I usually refill the kleenex after about three or four hours.
Disclaimer: These statements have not been evaluated by the Food and Drug Administration, or by any veterinarian. All information, including any product or technique mentioned, is for educational purposes only. None of the information is intended to diagnose or treat any disease.