[Ma3ma3a]

Hi i have two young cockatiels, i don’t think we are bonding well. When I try to pet them or scratch there heads they start biting and whistling help please.
Note: they like sitting on my shoulders.

 

[Jo Hess]

Not all birds like a scritch from owner. I'm on my 6th tame tiel over 20 years and he won't let me touch him at all! Wiill go for a serious bite to me if I try which is new and hard for me. Past tame tiels would take scritches forever to the point where my fingers and hand felt like couldn't do it anymore. In fact they'd bump my hand for more and more.
By your pictures, I'm guessing you might have a boy and girl, in which case they will be more interested in each other touching rather than the parrent.
If they like sitting on you, you know they are tame. I personally would never bring in 2 tame baby tiels in at the same time as they would naturally gravitate to each other which doesn't strengthen the bond to you. Maybe if you separate them by room which I would not ideally want if me, as they would no doubt keep calling out to each other.
No clear cut answer to that other than don't take on 2 tame tiels at the same time as they can revert back to not being tame when near and around each other.