When in the stronghold, the leader could be heard talking:
Stronghold leader: Mister Strain has written to our stronghold with words on encouragement: "To my most favoured Blighters. We’re not daft enough to remain ignorant of the threat that these so-called Rooks pose on our territory. I urge you to clip their wings but keep their brains intact for my own enjoyment. I will be in touch. Cletus." There you have it! Keep a close eye on your surroundings, they’re a sneaky bunch.