Basically you provided your Cockatiel with a nice nest! LOL The regurgitation was a hormonal/mating behavior. What you saw as hide and seek, was really him establishing his territory and nest, and checking for rivals or predators. I would recommend you take the new “nest” away, also. He has already escalated to hormonal behavior, and male cockatiels can get very obsessed with a nest or object when they get hormonal and don’t have a mate. You would never want to provide something like this for a female, because it can cause chronic egg laying. But there are health issues that a male can suffer from, too, if he remains in a hormonal state. To help you understand, a cockatiel pair would only use a nest during breeding season. When the days get shorter and the weather changes, the pair leaves the nest and returns to the flock. They will not use a nest again until the next year when breeding season begin. They mostly sleep in trees, with the rest of the flock for protection. In captivity, the indoor environment is typically ideal for breeding year round. As Cockatiels get mature, the owner often needs to make some changes to prevent the bird from being hormonal year round – particularly with females. With a male, he can get too obsessed with his nest or an object. Sometimes a male will refuse to leave the nest except to eat or drink. He might choose an object as a mate and regurgitate obsessively on it. He can get territorial and very aggressive. In some cases his urge to mate gets so bad, he can suffer from a prolapse through his vent – the place his poop comes out of. To avoid this scenario, it’s best not to give him anything that he can use as a nest – no boxes, bird tents or huts, no cozy places inside or out of the cage. If he gets obsessed with a toy, take it away and give him something different. It’s better to prevent this behavior than try to deal with it once it begins. As you observed, he was stressed when he lost his first nest, but improved since you gave him a new nest. I would remove it, and at the same time, give him some new toys and ideally, move his cage to another place in the room. This type change and disruption can break the hormonal cycle, because suddenly his environment isn’t as stable as he thought and it no longer a good place to establish a territory and nest. In captivity, some males in a breeding pair can get so territorial, they fight the hen and stop her from going into the nest box. For whatever reason, the males can be more inclined to somewhat short circuit when it comes to nesting in captivity. So by making the changes, he should remain a good pet and not become aggressive or withdrawn.
Thank you for asking Lafeber,