Sexual Imprinting: Effects of Various Regimens of Social Experience On Mate Preference in Japanese Quail Coturnix Coturnix Japonica

The present investigation has focused on the relationship of social experience during different developmental stages and subsequent mating behavior. Japanese quail Coturnix coturnix japonica were employed as subjects in that these avians become sexually mature as early as 42 days posthatch and they readily mate in an experimental apparatus. Four different treatments of exposure to albino Japanese quail were compared on a number of measures to determine how a particular regimen of social experience might affect social behavior in sexually mature males. The four experimental treatments were: First, exposure to normal age-mates only for either the first 5 or 20 days posthatch and then isolation from the 2ist day posthatch (NEX). Second, exposure to albino age-mates for the first 5 days posthatch and then isolation (SEX). Third, exposure to only albino age-mates during the first 20-25 days posthatch and then isolation (PEX). Fourth, exposure to albino age-mates from day 16 through day 25, and then isolation (LEX). The first measure obtained was the experimental virgin male's approach to a confined female in a simultaneous choice test between a normal and albino female. This measure proved to be an unreliable predictor of mate preference except in the case of the NEX group. Hence, except for those cases wherein subjects are reared with typical social objects can one expect that measures such as the approach response be related to more typical social interaction such as mating. The second observation was the mount preference for either the albino or normal female in a simultaneous choice test. Both the NEX and SEX groups selected normals 100% of the time. The PEX group selected albinos in all but one case. The LEX group was essentially equivocal with respect to a preference; 6 selected normal females and 4 selected albinos. This observation demonstrates that it is possible to establish the albino coturnix female as the preferred sexual object on the basis of a program of social experience. The data are discussed in terms of mechanisms that may serve to produce the observed differences among treatment groups. The final observation was whether or not coturnix males would mount albino females (within five minutes) when they were presented alone. This later observation served to differentiate the NEX and SEX groups and suggested that sexual responsiveness toward a particular social object may result from more than a single influence. Again, data from the albino test were discussed in terms of the mechanisms that were thought to be responsible for the observed differences among groups. An imprinting mechanism is thought to be responsible for the selection of albinos in the simultaneous choice test for both the PEX and LEX groups. The rationale for such a conclusion was based on the difference between the SEX and LEX groups in the number of subjects selecting an albino female in the simultaneous choice test. No members of the SEX (early exposure period) group mounted albinos in the simultaneous choice test, whereas 4 LEX's (later exposure period) mounted albinos in the simultaneous choice test. This difference was concluded to have resulted from social experience at a later ontogenetic stage rather than due to the increased duration of exposure in that the LEX group was exposed to normals for 15 days (a greater amount than the 10 day exposure treatment) and the SEX was not exposed to normals at all. A habituation-sensitization mechanism is thought to be responsible for the difference in mounting albino females in the albino test between the NEX group and the SEX and LEX groups. No NEX mounted an albino female, whereas all SEX and LEX males mounted albino females. This interpretation is based on the observation that avians generally manifest increased fear responsiveness toward newer objects after the first few days posthatch, and that experience with novel objects has been shown to reduce subsequent fear responsivity toward the experienced object. Further, it is assumed that in addition to the generalization of habituation from the earlier exposure to albinos there also was some generalization of sensitization to albinos as social objects. The coturnix appears to be a highly suitable species for the further study of those parameters effecting preferences for albinos in a simultaneous choice test.