Movement data from wild predator-prey encounters and controlled human catch-tag games have been combined to create realistic simulations of high-intensity movement dynamics and energetics – before transforming them into a publicly accessible video game. This game utilises a citizen science approach to data collection and is helping to further our understanding of the role of movement decision-making and fatigue in life-or-death encounters.
Intense physical exertion during predator-prey chases can trigger fatigue in both participants, which is defined as the reduction of muscle and movement capacity when operating above a critical threshold. The ability of an animal to capture or elude its opponent is often determined by its capacity for speed and agility before becoming fatigued.
This project, presented at the Society for Experimental Biology conference in Florence, Italy, highlights how real movement data have been captured and transformed into simulated models that allow for human decision-making, so the team can now create more accurate simulations of predator-prey interactions.
Dr Baptiste Morel, an associate professor at the University of Savoie Mont Blanc, France, leads the Force-Velocity-Endurance (FoVE) team that are interested in evaluating the physical abilities of athletes across various sports.
The inspiration for this project came from a collaboration between the FoVE team, who primarily work with human movement, and an ecology lab, who focus on animal movement. "We started to apply the methods that we developed for sports science to the animals in the wild, so we can have an estimation of their physical ability and how much of this ability they will use," says Dr Morel.
However, high-quality movement data from wild predator-prey chases, comparable to the high-resolution GPS tracking used in professional sports, is limited and practically impossible to produce in controlled conditions. "It's interesting data because it comes from real life, but it's not possible to control these experiments and understand how their physical ability will lead to fatigue or how the prey might escape or not," says Dr Morel.
To overcome this data limitation, Dr Morel and his team used human athletes taking part in chase-tag games as models to compare against the wild predator-prey encounters.
"Chase-tag games are not as intense as true predator-prey encounters, as lives are not typically at risk. However, the roles of predator and prey are so deeply ingrained in animal nature that even without real danger, the game still triggers a high level of physical exertion and intense anxiety," says Dr Morel.
Movement characteristics were captured from 16 human athletes taking part in "chase tag" interactions, including force, velocity and endurance. These pursuit scenarios simulated iconic predator-prey encounters, and the participants' movements were tracked by high-frequency GPS and accelerometery.
The team investigated fatigue using two methods. Firstly, by having the humans perform a sprint before and after the chase and comparing the reduction in physical capacity to move. Secondly, by taking blood samples to measure the levels of lactic acid, a marker of muscular chemical disruptions that contributes to fatigue.
Control over the chase-tag scenarios enabled the team to capture a wide range of behavioural data. "For example, we ran experiments with ambush predation over really short distances, and others with long-distance tracking," says Dr Morel.
Over the last year, Dr Morel and his team have used their findings to develop an innovative online game that simulates the real-world predator-prey encounters with a variety of animals, including wolf, deer and humans. Since virtual simulation now makes anything possible, players can even step into the shoes of extinct species like the Tyrannosaurus rex.
Players take the roles of predator and prey species and chase each other across a digital landscape until either the prey is caught or they survive long enough to escape. Real movement and fatigue calculations have been used to improve the realism of the game.
"We thought that this could not only be a really interesting to share our science, but it could also be a participatory way of doing science," says Dr Morel, who is very interested in assessing how representative the digital game will be compared to the real human data they have collected.
"For example, we have wolf and African wild dog data where they can hunt persistently for several tens of minutes over kilometres of a chase" says Dr Morel. "But the average chase length for a cheetah is just 200 meters because after they ambush, they start to fatigue and usually will not catch an antelope after that."
The game 'Run FoVE your life' will be soon available for people to play online. Anyone with a computer and an opponent will be able to play.
