Effect of losing a fight on later agonistic behavior toward unfamiliar conspecifics in male Syrian hamsters

In many species, agonistic interactions result in social relationships that are stable over time. In Syrian hamsters, two unfamiliar males that are placed together will fight vigorously and a clear winner/loser relationship is usually established. In sub- sequent interactions, the loser will flee soon after detecting the familiar winner. Here we tested the hypothesis that losing a fight with a conspecific will affect future agonistic interactions not only toward that individual (i.e., the familiar winner) but also to- ward unfamiliar conspecifics. To test this hypothesis we paired two Syrian hamster males in three trials on one day in which the loser had the opportunity to escape the winner. The next day the loser was paired with an unfamiliar male, also for three trials. If he lost again, he was tested on a third day with a third unfamiliar male. Subjects were those males that were losers on all three days. The latency to escape on the first trial on Days 2 and 3 was significantly shorter than on the first trial on Day 1, indicating that losing against the first male affected the response toward unfamiliar males. However, the latency to escape on the first trial on Days 2 and 3 was significantly longer than that on the third trial on the preceding day, indicating that a loser treats unfamiliar males differently than a familiar winner. These results suggest that a defeat during an interaction with one male affects later ago- nistic behavior towards other, unfamiliar males (Current Zoology 57 (4): 449-452, 2011).