Looking beyond the light: how does artificial lighting at waterholes affect mammal behaviour?

Earlier this year, I wrote a blog post about one of my PhD dissertation chapters on carnivore diets. A few weeks ago, we kicked off data collection for another one of my chapters which focuses on determining the effects of artificial lighting on mammal behaviour at waterholes.

Tourism is one of the main economic drivers in some parts of the world, especially in regions of sub-Saharan Africa. But despite being so important and widespread, the effects of wildlife-based tourism on wildlife behaviour and movement are still poorly understood. We know there are positive impacts on wildlife due to tourism. Aside from establishing protected areas and local economic drivers, wildlife-based tourism can raise public awareness and education, facilitate conservation efforts, and promote research opportunities. Artificial waterholes designed for tourist access provide vital resources for animals, especially during the dry season in arid environments. Additionally, tourists on safari access remote regions of protected areas where poaching occurs and provide a protective measure to deter poachers while scouting for injured animals.

The tow primary activities on an African safari: game drive and bush walk.

With that said, we also have an adequate amount of literature showing that wildlife-viewing tourism can have negative effects on wildlife, including habituation to humans, reduced reproductive fitness, modified activity patterns and predator-prey interactions, and increased stress hormone production. For example, one study showed that in response to tourist pressure, African elephants increased their aggression, moved away from tourist areas, and increased their vigilance at waterholes.

The view from Ongava Tented Camp main deck in front of the waterhole (© O. Evans).
Dinner scene at Ongava Tented Camp with the waterhole artifically lit (© O. Evans).

We know that both tourism and artificial lighting in many forms are increasing worldwide. However, most studies to determine the effects of lighting have been focused on migratory or nocturnal birds and bat species. Waterholes in some protected lands in Africa are often artificially lit at night for tourism purposes, including on the Ongava Game Reserve, since many charismatic species are nocturnal. While many studies have been conducted on wildlife during waterhole visits, none have studied the effects of artificial lighting on wildlife behaviours and temporal activity. There have also been few efforts to evaluate wildlife responses under varying lighting conditions. Regardless, the goal for my dissertation, and especially this project, is to develop optimized protocols that will maximize the tourism experience while potentially reducing human impacts on wildlife. And what could be better than an experimental approach to test the effects of artificial light at waterholes on animal behaviour?

A map of the waterholes for our study on the Ongava Game Reserve. Two waterholes will be lit by us for the experiment, two will remain dark, and three have been lit long-term at lodges.

For this study, we are using seven waterholes on Ongava, and we will compare the behaviour of mammals between two waterholes where artificial light will be new, two dark waterholes (our controls), and three waterholes that have been lit long-term at lodges.

At the two previously dark waterholes, we have recently installed solar-powered light stations powering 30-watt LED lights (see below), which are similar to the current lights installed at the lodges.

Top left: solar stations built to power LED lights. Top right: LED lights used to light waterholes at night. Bottom left: video camera indicated by the red arrow. Bottom right: camera trap box for recording images.

The presence and behaviour of mammals at each waterhole will be monitored using both camera traps and video cameras. Data is already being recorded as you read, and the cameras have been active since early August. However, the new lights will remain off until the end of the month, allowing us to collect data during a control period. Then the lights will be switched on early September for a period of two months, and then be switched off again. This will allow us to quantify not only the response of animals to the new light but also how long it takes them to return to their baseline behaviour, the one before we switched the light.

To analyze all the video data, we use BORIS – Behavioral Observation Research Interactive Software (Figure 3), an electronic ethogram software that allows us to play the videos and classify behaviours for each species. We will focus on vigilance, drinking, resting, and moving to/from/around the waterhole. We will document the number of individuals in the group and if there are other species present when a new animal arrives at the waterhole. We are also able to time the animal’s approach, to determine if it takes them longer to approach a waterhole based on the light condition.

A screenshot of ethogram software BORIS.

For each species, we will be determining time spent at the waterholes, time spent approaching the waterholes, the number of visits at the waterholes, and the number of each behavioural event. We will then compare those between waterhole types (long-term lit at lodges, dark, and recently lit by us) and determine the overlap for diel activity patterns between each waterhole type. This will allow us to visualize how the activity patterns for each species differs between waterhole type.

An example of diel activity patterns overlap plots for black-backed jackals (Lupulella mesolemas). Each color represents a different condition (i.e., newly lit, dark, or long-term lit).

Depending on our results, we will decide if we want to apply coloured filters to the lights and test for the same effects. For example, red lights are supposed to be less disruptive than white lights. We are also interested in putting timers on the lights to turn them off early, perhaps around midnight, to see if that modifies behaviours or temporal activity any differently.

Stand by for our results and project updates next year!