It sounds like he had quite a scare!
Covering half of his cage was going to be my first recommendation.
If he is still puffed up and acting lethargic, I would provide some heat in the form of a lamp over the covered part of the cage- about a foot away from the cage. This way if he needs warmth, he can get it, but if too warm, he can move away.
Keep noise levels down, and keep people from going in/out of his room frequently.
Keep his food and water available.
Give him a few hours to just settle down.
Assuming he was not injured during the fall, he should be fine by tomorrow.
If he is not back to himself by tomorrow- he may need to see his veterinarian. But be aware that car rides and veterinary visits are EXTREMELY stressful for canaries, and these birds can often pass away from the stress of a car ride or veterinary visit, especially if already debilitated. If he does need to see the vet, take things really slow and quietly. Keep his cage covered, and have the air conditioner on in the car- but not TOO cold.
I hope he is better by morning- please let me know if you have any other concerns to address.
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