“Vocal mediation of intrasexual competition in fallow deer”
In 2011 I received a postdoctoral fellowship funded by The Fyssen Foundation to work at Queen Mary, University of London. My research focused on the male vocalisations of the fallow deer (Dama dama).
The Fyssen Foundation was founded in 1979 by Mr. H. Fyssen, a French businessman who had long been interested in the scientific understanding of cognitive problems. The aim of the foundation is to “encourage all forms of scientific inquiry into cognitive mechanisms, including thought and reasoning, which underlie animal and human behaviour; their biological and cultural bases, and phylogenetic and ontogenetic development”.
Our 2012 research was supported by The British Deer Society
Background
Fallow deer are one of the most vocal deer species with mature males investing a large amount of time and energy in vocalising, groaning up to 3000 times per hour. Observational studies of fallow deer reproductive and communication systems have raised many questions about the vocal mediation of intrasexual competition. Fallow deer are highly polygynous and size dimorphic. Mating success is strongly related to dominance rank, and this is established before the rut. During the breeding season, fallow bucks lose approximately 25% of their body weight, mainly due to the cessation of feeding. Additionally, they invest a lot of time and energy in vocalizing and fighting in order to gain any mating opportunities. Male fallow bucks only vocalize during the breeding season and produce a single type of call, the ‘groan’. The groans of fallow bucks are individually distinctive, but also appear to encode the quality of the caller, reflecting changes in dominance from year to year. Finally, unlike signals of quality produced at the beginning of the breeding season (e.g., ornamentation) fallow deer vocalisations that are produced throughout the breeding season appear to reflect the current condition of the male, with calls becoming shorter, with fewer pulses and higher fundamental frequencies towards the end of the season. This observation suggests that groans are an honest signal of quality, changing to reflect the current state of the caller and potentially playing an important role in the mediation of male-male competition.
While these observational studies suggest that males may gain information from a rival’s groan about their identity, quality and fatigue, these hypotheses had not been tested experimentally and previous authors have highlighted the need for such an experimental approach. My study examined the roles of male fallow deer groans in individual recognition, the assessment of rivals and honest signalling during intrasexual competition.
Related Publications
Pitcher, B.J., Briefer, E.F., McElligott, A.G. 2015. Intrasexual selection drives sensitivity to pitch, formants and duration in the competitive calls of fallow bucks. BMC Evolutionary Biology 15:149 doi:10.1186/s12862-015-0429-7
Pitcher, B.J., Briefer, E.F., Vannoni, E., McElligott, A.G. 2014. Fallow bucks attend to vocal cues of motivation and fatigue. Behavioral Ecology 25:392-401 doi:10.1093/beheco/art131
Stachowicz, J.B., Vannoni, E., Pitcher, B.J., Briefer, E.F., Geffen, E., McElligott, A.G. 2014. Acoustic divergence in the rut vocalizations of Persian and European fallow deer. Journal of Zoology 292: 1-9
Conference Presentations
Symposium organiser with Dr David Reby “Applying the source-filter theory to an integrated understanding of mammalian vocal signalling” at Behaviour 2013, Newcastle, United Kingdom.
Pitcher, BJ, Briefer, E, Vannoni, E and McElligott, AG. Experimental evidence for signals of quality and motivation in fallow deer (Dama dama). Listening in the Wild (2013). London, United Kingdom.
Pitcher, BJ, Briefer, E, Vannoni, E and McElligott, AG. Experimental evidence for signals of quality and motivation in fallow deer (Dama dama). ASAB 2012. London, United Kingdom.
Pitcher, BJ and McElligott, AG. Signals of quality in an exceptionally vocal deer. SET for Britain 2012. London, United Kingdom.
Benjamin PITCHER 