User blog comment:Kogath/Monster Hunter 4 Ultimate for the Nintendo 3DS/@comment-6050823-20150222185350

Well, I found something interesting about Shagaru Magala and a reason why Chaos Gore Magala exist.

It turns out that black mist that they use to cover an area in the virus is the way they mark their territory and a way to prevent any Gore Magala within an area from properly molting. Very few Gore Magala get to reach their peak as an adult. Gore Magala barely have any control and barely any resistance against the virus so if they molt near or in an area where a Shagaru Magala is at, they won't be able to molt properly and will become a Chaos Gore Magala.