Olfactory cues and movement: Stimuli mediating intraspecific aggression in the wild Norway rat

Established male sibling pairs of laboratory-bred wild rats (R. norvegicus) in enclosures and in 4 experiments observed their aggressive, amicable, and sexual behavior following the introduction of conspecifics. Intact male Ss behaved amicably toward familiar male conspecifics, both aggressively and sexually towards unfamiliar anestrous and estrous female conspecifics, and aggressively toward unfamiliar male conspecifics. Anosmic males exhibited amicable and sexual behavior toward unfamiliar males, but did not initiate aggression toward them. The storing of a member of a resident pair in a cage with or without wood shavings, urine, and feces from a foreign colony did not affect behavior toward him by his cage mate. The storing of a foreign male in the wood shavings, urine, and feces of a colony did not affect behavior of that colony toward him. Cessation of movement on the part of an intruder of either sex inhibited attack, while immobile anesthetized male intruders elicited aggression. When presented simultaneously with moving and anesthetized intruders, resident Ss attacked only the former.