I have a african grey congo he is picking lot of feathers from few days is this the signs of stress

but my bird is whistling, playing and his diet is normal can somebody guide me

Take a look at the feathers he is losing. Look at the end of the shaft . Is it normal? Meaning, does it have a smooth, whole looking appearance? Or is it jagged and frayed?

Look at the Grey "feather part"called the "barb". Are the ends of the barb smooth looking? Or do they look ripped or clipped?

This will give you an idea whether he is just molting or if he is plucking out or barbering his feathers.

If you have jagged shaft ends or ripped looking barbs, he might be plucking. If the feathers he has molted are normal in appearance, he is simply going through a molt.

But if he is looking sparse and the feathers are thin, as though new feathers are not growing back, he may have a dietary deficiency, and a blood panel is in order to discover what is lacking in his diet so it can be corrected. He will also be tested for any bacterial or fungal issues.

For instance, the ideal Calcium to Phosphorus ratio in an African Grey is 2 to 1. You can find out from a blood test what it is and an Avian Vet might prescribe supplements and a change of diet.

This will give you a better picture of what is going on with him so if there is a problem, at least you'll know what's going on.

Keep an eye on him and pay attention to those feathers. That will keep you up on what's happening so you'll know how to react if a problem pops up.