The war between pigs and birds is nothing new. Those two species are common antagonists... maybe not in nature but in games. The reason they fight now is that the winter is coming, and the birds have no warm place to hide. So their evil leader decides itll be the best to attack pigs on their peaceful farm...
The suprise attack succeeds and the pigs are forced to live their home. But they wont let some birds just kick their butts like that. So they bought a cannon and they gone wild to fight back!