It's usually my other birds. He's around them 24/7 and has been for the past several months. And then one of them will make the same noise it's done 100 times before that day and suddenly my cockatiel will decide it's terrifying and take to the air. But in this most recent case it was because he was trying to work out how to get back into his cage off the top, and almost slipped off.
I hate to say this but he really seems to be on the... lower end of the intelligence spectrum. He has a poor understanding of 3D space for a flying animal. I've watched him several times be on top of his cage and walk around in circles backwards attempting to walk down to the inside of his cage. Instead of making his way down the side and through the cage door. Usually I have to go "rescue" him from the top of his own cage and put him back inside or he'll be up there all night.
I'm not sure if this is the main factor in why he's so odd.
I hate to say this but he really seems to be on the... lower end of the intelligence spectrum. He has a poor understanding of 3D space for a flying animal. I've watched him several times be on top of his cage and walk around in circles backwards attempting to walk down to the inside of his cage. Instead of making his way down the side and through the cage door. Usually I have to go "rescue" him from the top of his own cage and put him back inside or he'll be up there all night.
I'm not sure if this is the main factor in why he's so odd.