Cockatoo not eating anything other than sunflower and formula

[Midrac]

Hello!
I need little help with my new cockatoo. I'll be very grateful for all sugestions.
First some details:
He is sulfur crested cockatoo around 7 months old. I got him around 3 weeks ago and I was supposed to still give him formula once a day. Fast forward 3 weeks and he still refusing to eat anything other than formula. He was and still eating a bit on his own (not much) bit thats far from enough. Lately im mixing formula with grinded pellet to make him get used to pellet taste but its not helping. He is gladly taking it from syringe but refusing to touch it on his own.
Few days ago I went to the vet and he is fine (wating for pbfd and bfd results but almost for sure he is negstive), the only concerning thing is his weight so I was advised to make him gain a bit. His weight was always around 520g before feeding and now he is 500g. He feels super skinny
Also he never eats in cage (maybe sometimes sun flowers). He eats only when me or my wife are next to him.
Now, what he eats:
1. Formula
2. Formula mixed with Pellets ( 50/50)
3. Sunflower seeds
4. Fruits (strawberries, apples, bananas) - kinda any sweet fruit is fine for him.
That's about it.
What he is refusing to eat, or more like what he is only tasting (he licks it few times and ignore the rest):
I tried almost anything, 4 different Pellets, peas, corn, pumpkin, carrots, sweet potato, dried fruits, dried veggies, made a lot of different warm foods (mixed with pellet and not). I have no idea what to do. Warm/cold and dry or wet food is same to him. At best he takes few bites and goes away. He also gets angry at pellet and throws it around.
Should I keep feeding him formula (and give it more than once a day) or give him as much sunflowers as he wants? I know that both of this solutions are bad but I think its better then him loosing more weight. How can I make him eat on his own and how can I make him graduate from syringe feeding? I'll appreciate a lot any suggestions what I can do.

Here photo of this cute baby

 

[Mizzely]

So 3 weeks is a very short amount of time. Babies can be a lot more open to new stuff, but birds as a general rule are neophobic - weary of new things. Often they don't know food is food just because it's put in front of them. My Jardine's took 3 years to touch fresh foods!

If it were me, I would continue to feed him formula; right now he's not getting many good calories otherwise. I would offer other items daily, and I wouldn't change things too much yet. It's tempting to change stuff all the time to see what sticks, but I think consistency can also help. Instead of seeing the same thing in the bowl every day for a few weeks and then finally deciding to try it, it sounds like he's seeing things change so rapidfire that he can't get used to something before it's already replaced with another new thing he can't get used to. Make sure to be eating things in front of him too, especially out of the same bowl if you can! That way he sees you (his flock!) testing stuff out too (yes, even the pellets sometimes )

So, try a bowl of the same pellets for a week, as an example. A bowl of the same types of veggies, etc.

I'm not a baby expert by any means, this is just my gut feeling on how I would go about it.

Formula is not bad. It's also more than just food. It is comfort and reassurance, confidence and trust building.

 

[Toy]

My U2 was a good 10 months old before she weaned. I got her at 7 months & was told to feed her soaked pellets 3 times a day. I was given Zupreem Natural pellets & told to soak them in hot water until soft, then drain off excess water. I hand fed them to her one pellet at a time. She'd eat 10-14 pellets per feeding. She also had in cage foods, which were some seed mix & pellets. Cockatoos love to throw/toss their food. Mine is almost 25 years old now & still tosses her food.

I'd suggest keep feeding the formula, but also add in hand feeding of soaked pellets. If he takes to eating the moist pellets, slowly cut back on feeding formula. You need to "fake" eat some to show him it's OK to eat. Same with veggies. Also make sure he has in cage foods as well.

Most will loose some weight as they wean.