You're speaking with Dr. Michael Salkin. Welcome to JustAnswer. I'm currently typing up my reply.
I regret that my state board of veterinary examiners doesn't allow me to speak to customers by phone in this venue but other experts in this category may be able to assist you in this regard. Please let me know if you'd like another expert to do so and I'll opt out of this conversation. Please stay in the conversation if you wish.
Yes, your macaw should see an avian vet. Please see here: theparrotsocietyuk.org/veterinaryadvice/avian-vets/ Ectoparasites such as mites and lice aren't commonly the cause of how he looks. Moulting, self-mutilation, and infections (bacterial, fungal, and viral such as the circovirus of psittacine beak and feather disease) need to be considered and tested for. The avian vet will need a history of when your macaw began looking as he does, what part of his body lost feathers initially, your macaw's diet, and whether or not you've seen him preening excessively.
I regret that I can't be more specific for you from here. I, too, would need to take a thorough history and perform a thorough physical exam on your macaw including blood and urine tests and cultures of feather follicles and specialized serological testing. Please respond with further questions or concerns if you wish.
You don't. The avian vet collects droppings and urine from him, draws blood from a vein, a perhaps cultures a feather follicle. While he's at the vet, his beak and claws can be clipped for you. Because he's new to you, it's a good time to have him throughly examined even if he didn't look so scraggly. Please continue our conversation if you wish.
He'll need to be transferred into a carrying cage available in pet/agricultural merchant stores.
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