Stalkers are very stealthy creatures, and prefer to hunt in packs. They often stay in packs since they are pretty weak Evolved, and are more intuned with their animal instincts. They often times end up clawing out their eyes, and their ears off. So they do not need to see to hunt, and will usually use the ears on the top of their head to hear their victims. This will be a more common Evolved for people who are very athletic, and psychopaths or sociopaths.