I know all the scientific facts about birds not having a good sense of taste, but I can not believe it.
I keep chickens, doves, and finches and I can tell you they have a very good sense of taste.
If I feed my finches some seed that is fresh in one cup, and some older seed in another, the birds will prefer to eat the fresh seed. To us the seed looks and feels the same - so how do they know which bag is the freshest?
If I use 2 brands of egg food, one will be preferred to the other, even if they look and smell the same to me.
My chickens will love some vegetables and greens, but only eat others begrudgingly or not at all, even if they look the same colour and have the save texture.
Once I offered my ringneck doves some chick starter that was left over from the chickens. They would not eat it. I then noticed it had gone off slightly and smelled a bit strange. I gave them fresh chick started and they ate the lot!
Also if I add vitamins to the water, some of my doves will hold off drinking it, even if the liquid is still clear.