It all started during a field trip through the University of the Witwatersrand, when someone noticed that nightjars call more during full moon nights.
This lead to discussion on how moonlight may affect the nocturnal movement patterns of large prey animals, and large predators such as lion.
As it happened, data were available on movement for zebras, wildebeests and lions in the Orpen Gate area of the Kruger National Park. So, a team of researchers set out to investigate the influence of the lunar cycle on both zebra and wildebeest. The results were more interesting than anticipated:
“We did not know what to expect when we started with the project. We assumed that zebra and wildebeest would increase their activity over the full moon given the increased likelihood of detecting ambush predators with increased light,” said Dr Lochran Traill from the Centre for African Ecology at the University of Witwatersrand.
The team analysed hourly location data from collared zebras and wildebeests, split into full moon and new moon periods only. This was then compared to location data received from lion’s collars in the area. They anticipated that prey animals would be more active over the full moon, when more light was available, but they found no difference at all in movement during new or full moon – when lion were not close by.
“We found no difference in the night time movement of prey animals over full and new moon when lions were not around,” says Traill. It is only when lions were in close proximity that they recorded changes in the animals’ behaviour. “When lions were nearby, the average speed (metres per hour) of prey animals was far higher, especially over new moon. This is most likely when the lions were hunting.” While wildebeests fall prey to lions, this was more applicable to zebras.
The explanation appears to be both physiological and ecological; zebra are hind gut fermenters, they need to feed during the night, despite the dangers. The phases of the moon therefore have no effect on their behaviour.
Wildebeests on the other hand are ruminants and do not need to forage throughout the night. Moreover “they occupy open, grazing lawns at night and don’t dare move out because there might be lions lurking in the grass. Whether it is full or new moon makes no difference to them.”
So moon phase per se has little effect on zebra and wildebeest activity patterns. Rather the effect of moon on lion hunting activity, as well as the physiological adaptations of zebra and wildebeest drives night time movement.
Written by René de Klerk– SANParks Times Reporter
Pictures: Nicolene Olckers and René de Klerk
Content courtesy of SANParks Times: www.sanparkstimes.co.za