Wronski, T., Apio, A., Plath, M. (2006) The communicatory significance of localised defecation sites in bushbuck (Tragelaphus scriptus). Behavioral Ecology and Sociobiology. 60: 368-378.

Wronski et al (2006) investigated the potential function of communal defecation sites in an African antelope species. Many hypotheses have been propsed about the function of such localized defecation sites (LDS) including parasite avoidance, hiding group size from predators and masking the presence of young or sick individuals from predators. Here the authors tested the hypothesis that LDS serve to mark group territories predicting that LDS will increase towards the periphery of territories. To test this hypothesis the Wronski et al examined the density of LDS within the homerange of bushbuck (Tragelaphus scriptus) and found that their predictions about a territorial function were not supported. The authors then went on to incorporate other information into their analysis to test non-teritorial explanations for the patterns of defecation they observed. The authors found that females defecated and urinated more frequently in LDS than did males, but males visited LDS more frequently without defecating or urinating. This led Wronski et al to conclude a inter-sexual communication function for LDS where females signal to male, and to a lesser extent female, receivers, presumably about reproductive status.

Territory demarcation was a good candidate for the function of LDS as we discussed in class, chemical territorial signals are common and effective where territories are long lasting. Dispite not finding a territorial function for LDS in this species it is likely that these communal defecation sites may serve this function in another species. While an actual communicatory function was not completely demonstrated, as the outcomes of the communications were not examined, there is strong evidence in this study for an inter-sexual communicational function for bushbuck use of LDS. Due to the apparent female to male signal direction it is likely that chemical signals left at the LDS by a female advertises her receptivity to males either to act as an attractant or as a way to avoid harassment from males during their non-receptive periods. This allows males to avoid paying costs associated with searching for females that may be unreceptive, or could increase their efficiency in finding a receptive female. The authors also noted females were sometimes the receivers of chemical signals from other females. This kind of signal could function in synchronizing oestrus or parturition among females which could have a number of selective advantages.