Charlton, B. D., D. Reby, and K. McComb. 2007 “Female red deer prefer the roars of larger males”. Biology Letters 3: 382-385

Male red deer are known to compete with one another for mates. The roars created by these deer have previously been shown to impact both the competition between the males, as well as female ovulation and the likelihood that the female will choose a particular male to be her mate. In this experiment, Charleton et al. attempted to determine the affect of formants, resonance frequencies of the vocal tract, on female mate choice. Formants have previously been shown to provide accurate information regarding the body size of the individual producing the call.

The research consisted of two experimental sessions. In the first, two different play-back stimuli were used which simulated male red deer, one with a large vocal tract length and therefore large body size and one with a short vocal tract length and therefore small body size. The playbacks were designed to simulate two males competing for females. After listening to the sounds once, the females were returned to the enclosure an hour later. The simulation was played once again in order to observe in which direction the female went – either towards the simulation of the larger or the smaller male roar. The second experiment was designed in a similar way except that the two sounds consisted of an abnormally long vocal tract length and therefore an abnormally large deer and a short vocal tract length and therefore an abnormally small deer.

When the results were analyzed in the first experiment, it was found that there was not a significant difference between the amount of time that the female deer spent towards one end of the enclosure than the other. However, when the second experiment was analyzed, the female deer did spend a significantly longer period of time at the end of the enclosure where the simulation of the abnormally large deer was played.

In class, it was discussed that red deer compete using roars with other males in order to find a mate. However, it was not discussed what the effect of the roars has on the female selection. This article demonstrated that the roars not only impose a sense of ferocity from one male to another but also influence female choice. Intuitively, this makes quite a bit of sense as the lower formant or the louder roar, would be created by a deer of a larger size. As such, this deer would probably be more able to care for and protect the female as well as any offspring that they would produce. As Charleton et al. conclude in their paper, roars which indicate larger callers may contribute to selection , not only through competition between males but also in regards to female preference.