Masking of the zeitgeber: African wild dogs mitigate persecution by balancing time
Rasmussen GSA., MacDonald DW.
The African wild dog Lycaon pictus is endangered, with anthropogenic impacts, pack size dynamics and competing predators explaining its decline. Relative to solar and lunar events, analysis of diel activity in two parapatric Zimbabwean populations revealed behavioural plasticity in response to human activity. In Hwange, human presence was low; in Nyamandlovu, human presence and persecution were high. In both populations, Lycaon frequently hunted by moonlight, with 3-4lux of light restricting nocturnal hunting to 13 days/lunar month. With diurnal hunts commencing at 'civil twilight begin' and ending at 'astronomical twilight end', light intensity was confirmed as a limiting factor. Nyamandlovu dogs exhibited behavioural plasticity, demonstrated by scattered rather than clumped organization when at rest, and masked the zeitgeber by utilizing evenings and moonlight for more days under suboptimal light conditions than did Hwange dogs. Significantly, different allocation of morning, evening and moonlight hunts between Hwange (47%, 36%, 15%) and Nyamandlovu (28%, 31%, 41%), reduced the temporal potential for human encounter by 64%, but increased this potential for hyaena and lion encounters by 70% and 37%, thus highlighting the trade-off of this switch. Finally, we tentatively conclude that the cue masking the 'zeitgeber' is risk, rather than gain related, and could be seen as an evolutionary 'emergency exit', the understanding of which is important to conservation in landscapes that are increasingly dominated by people. © 2011 The Authors. Journal of Zoology © 2011 The Zoological Society of London.