green cheek conure suddenly aggressive — help!

My Quaker parrot Ruby has been super bitey the last week. Nothing changed in the environment that I can think of. Could it be hormonal? They're about 5 years old.

My vet in Ajax suggested putting treats inside paper cups, folded paper, or tissue for foraging and I noticed a change within the first week. Highly recommend.

Do you have other pets in the home? My Pionus started acting differently when we got a cat.