Peahens do not Prefer Peacocks with more Elaborate Trains

Traditionally, peafowl experts believe that the male train is the major morphological trait that directly influences mating success. In class, we discussed the possibility of the elaborate peacock train as a signal to coax females or potentially as a status of reproductive success of an individual. The train is an elaborate morphological characteristic and can vary in length and number of ocelli (eyespots). It is thought to have continually evolved in response to female preferences in mates and could be an indicator of males with “good” genes associated with a high reproductive success rate. However, there is evidence both for and against the male train as an indicator of mating success and there is no consensus as to which characteristics of the train are most favored by females. The purpose of this study was to investigate whether peahens prefer peacocks with longer trains or more ocelli, if symmetry of ocellar arrangements affects male mating success and if the male shivering train display affects male mating status.

Researchers defined male mating success as the total number of copulatory events per year. They determined male mating status (rank) based off of female courtship behaviors. Females made frequent visits, termed “run-rounds,” to preferred peacocks prior to every copulation. Each train was photographed to determine the number of eyespots present. A fluctuating asymmetry (FA) index was calculated for each train to indicate the degree to which the eyespots were symmetrical. Complete symmetry was assigned an FA of 0; the smaller the FA, the more symmetrical the train. In addition, researchers looked for “shivering” behaviors which were classified by a peacock that would shake his train in the direction of a nearby female to produce a rustling sound.

Over a seven year period, results showed that train length and the number of eyespots were not related. The length of train had no effect on variances in mating success. In a comparison study of those peacocks that were predated upon versus those that survived, there was no difference in number of eyespots. However, train length in predated males was significantly greater while FA indexes were only slightly greater. More successful males did produe more bouts of shivering and spent a longer amount of time shivering. Since this shivering was provoked by female “run-rounds,” it was deemed dependent on female presence.

The results of this study contradict previous studies that concluded that: male train morphology positively influences mating selection, mating success increases as the number of eyespots increases and males with longer trains showed greater survival rates. In the present study, females did not choose males with a greater number of eyespots nor did they prefer males with symmetrical ocelli. Ultimately, none of the male train measures consistently influenced female preference.

This study produced no evidence that supported the claim that peahens express preference for peacocks with more elaborate trains. Researchers concluded that peacock trains were not the universal target of female choice. They speculated that the male train is a characteristic for which female presence has waned over many years; however it still exists because it is some sort of cue to receptive females. In conclusion, peahens are likely to choose mates based on cues other than those exhibited by the peacock train.

Takahashi, M., Arita, H., Hiraiwa-Hasegawa, M., & Hasegawa, T. (2008). Peahens do not prefer peacocks with more elaborate trains. Animal Behavior. 75, 1209-1219