User blog comment:Kogath/Monster Hunter 4 Ultimate for the Nintendo 3DS/@comment-19936604-20141029103557/@comment-22748142-20141029214643

Just a part of evolution to counter the threat.

In the past, Cham have to standing still or moving slowly to keep invisibilty working , but that won't help them to stop the hunter from striking their back legs.

Thus Cham grews more aggressive, learn to move faster and become invisible for a short time to strike their prey from different angle within 3 secs to catch them off guard. I have seen something like 3 blademasters ganging up a Cham, Cham suddenly becomes invisible and then after 2 secs , reappears right behind the Gunner , beat him up in 1 strike.