Call me maybe? Evolutionary purpose of false mating calls in Pavo cristatus peafowls

Date: March 5, 2014

Source: The American Naturalist  

Summary: A recent study conducted by Roslyn Dakin and Robert Montgomerie at the University of Chicago aims to understand the purpose of false mating calls by Pavo cristatus peafowls.

Evolutionary biology denotes signaling as the communication between organisms. Dishonest signaling, then, is the method by which an organism executes a false alarm to others of its species. For many reasons, dishonest signaling could threaten a species, especially if a predator is involved. In this research however, dishonest signaling has been found to be used by Pavo cristatus peacocks quite frequently: a third of all the mating hoots performed by males. Though generally, peafowl hoots are meant for mating or for attracting peahens (attempt hoot), peacocks have been using it even without the presence of the peahens (solo hoots). It is difficult to explain the purpose of a commonly used dishonest signaling, given its threat to species, which is precisely why this research is novel. The research conducted aimed to understand the purpose of the dishonest signaling executed by the peacocks. It hypothesized that the hoot calls represented male mating success, and thus the preferred males (who were able to mate) hoot more frequently than the unpreferred males.

Researchers observed a total of 39 Pavo cristatus peafowl between 2007 and 2010 at four different sites. Each of the males’ matings as well as hoot calls (attempt and solo) was recorded to determine whether or not a correlation existed between male mating success and male hoot calls. Researchers investigated other various factors such as the attractiveness of the male, the effect of the solo hoot call, the effect of only the hoot on peahen (without male behavior suggesting copulation).

The results of the study seem to bolster the hypothesis as total (attempt and solo) hoots of Pavo cristatus peacocks are representative of a male’s reproductive success as the rates of hooting by a male are linked with female visitation of the male and male copulation with the female. However, though not heavily supported, the results of the study also suggest that the benefit males may gain from false mating (solo) calls would be a slight increase in visitation of female peahens. In addition, the researchers also believe that the dishonest signaling of the males might attract female peahens who might otherwise not respond to mating rituals. Thus, the peahens are mating with lower quality males, falling victim to energetic costs. The researchers suggest a possible explanation for the presence of false mating calls despite its pitfalls: the solo hoot call may be a learned trait part of a reward based learning system where the reward is the ability to mate with females. Further research is needed to provide evidence for this theory.

Dakin R. and R. Montgomerie. 2014. Deceptive copulation calls attract female visitors to peacock
            leks.The American Naturalist 183: 558-564.