In fables and traditional stories, when birds (or any group of animals) decide they want to change their king, it is usually due to one or more of the following reasons:

• Injustice or Tyranny: The current king might be cruel, unfair, or oppressive, using his power to harm or exploit his subjects rather than protect them.
• Incompetence or Weakness: The king may be seen as ineffective, unable to make wise decisions, defend his kingdom from threats, or ensure the well-being of his flock.
• Selfishness or Neglect: The ruler might be too focused on his own vanity, comfort, or power, neglecting the needs and concerns of the birds he is supposed to govern.
• Desire for a Better Leader: They might believe that another bird possesses superior qualities, such as greater wisdom, kindness, strength, or a more democratic approach, which would lead to a more prosperous and peaceful existence for all.

These themes are common in various folklore and fables where animals choose or challenge their leaders, often serving as allegories for human governance and societal dissatisfaction.