 Primarily nocturnal , Gaboon vipers have a reputation for being slow @-@ moving and placid . They usually hunt by ambush , often spending long periods motionless , waiting for suitable prey to happen by . On the other hand , they have been known to hunt actively , mostly during the first six hours of the night . In <unk> , Ghana , they were regularly killed around some <unk> in an open area with the forest some 500 meters away — a sign that they were hunting rats in the grassland . They are usually very tolerant snakes , even when handled , and rarely bite or hiss , unlike most vipers . However , bites by bad @-@ tempered individuals do occur . 
