Odors providing sexual information in Djungarian hamsters: evidence for an across-odor code.

Experiments were conducted to determine the repertoire of odors that are involved in sexual recognition and communication about reproductive state in Djungarian hamsters (Phodopus campbelli). By examining the preferences of males for odors of females over those of males, it was found that some odors support preferences across female reproductive states, other odors induce preferences only during estrus, and yet other odors do not elicit sexual preferences. Similarly, female preferences for male odors was restricted to just some scents. Males were also tested for their preferences for female odors from different reproductive states (diestrous, day before parturition, post-partum estrus). Four different odors were found to vary in attractiveness with these reproductive states, and there were three different patterns of change: (1) mouth and urine odors were attractive just during post-partum estrous; (2) midventral gland was most attractive the day before parturition; (3) vaginal secretions showed a graded pattern of attractiveness, peaking at post-partum estrus. These results show that different odors provide some redundant and some different information, and they suggest that an across-odor code could be used to provide very precise information about a female's reproductive state.