Agnonistic behavior in organized and disorganized cotton rat populations.

Agonistic interaction rate is significantly lower in groups of caged cotton rats (Sigmodon hispidus) from naturally occurring organized populations than in groups composed of strangers. Some type of social structure is apparently present between animals sharing a common area under natural conditions. After a 24-hour period, there is no significant difference in the behavior of the two groups, an indication that a social structure is rapidly formed in the disorganized groups.