Thank you, i can confirm this - no stalker there yet (only alpha, old alpha and prowlers). Basicly all the big island with Fort Vitoria tp contains few groups of chirpys (some have one or two stalkers usually).
Well actually main reason is that someone posted on Entropedia that they drop Devil's Tail. I want to either: confirm that or decide i have killed so many that getting at least one tail is very unlikely (it is hard if not impossible to prove that something actually does not drop). Person who reported this drop on entropedia is not from created account but from ip adress and he reported he got it from Stalker. So at least knowing they exist - i know it may have happened

.
About the Mutated one - i had no idea when or where they may spawn and my info on those is minimal

. But now i have more interest into it since Hurikkane mentioned it? August? Could you explain?
Falagor