Complex sentence: Cockatiels don't necessarily make good pets for very young children because they startle easily with loud or unexpected sounds and may bite out of fear of sudden hand movements, however, they can make good pets for well-behaved older children.
Split into simpler sentences: Cockatiels don't necessarily make good pets for very young children because they startle easily with loud or unexpected sounds and may bite out of fear of sudden hand movements. However, they can make good pets for well-behaved older children.