Anatomy of a hunt: Speed, strategy and survival
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Anatomy of a hunt: Speed, strategy and survival

November 17, 2019


Predators that chase down their prey
on the open savannah are some of the most athletic creatures on the planet. The cheetah is the fastest land animal and can run at speeds of up to 60 miles per hour. These extraordinary abilities have emerged through an evolutionary arms race where both predator and prey have
evolved to become faster and more athletic. But during a chase, it’s not just about strength,
speed and agility. It’s also about strategy. “So, we wanted to investigate
the actual tactics of a hunt: What the prey is doing to maximise its chances of evading the predator, what the predator is doing to maximise its chances of capturing the prey. We selected two pairs of animals: the lion and the zebra, and the cheetah and the impala. And we measured five different metrics. We measured the muscle power,
we measured their top speed, we measured their ability to accelerate or turn, and we measured their stride frequency. So to measure these things,
we used wildlife tracking collars. This is a cheetah collar, a zebra collar and a lion collar. The electronics are all very similar. On the top we’ve got a GPS antenna and solar panels, and this has got all the movement sensors that we use, the GPS, the accelerometers, the gyroscopes that actually capture the movement of the animal. These are fairly robust plastic, if
we look at something like the lion collar, this is 4mm polycarbonate,
effectively bullet-proof glass. So when we analysed these data, the predators were more athletic than the prey
in really every metric. They were faster, their muscles were more powerful, they could accelerate and decelerate more quickly. This makes sense, the predator has to be more athletic. The prey is defining the terms of the hunt, it is always one stride ahead and
the predator is always playing catch-up and reacting to what the prey has just decided to do. So it’s not surprising we see
greater athleticism in predators. So we have hunting data for the predator and
for the prey but we don’t have it for the same hunt. So we get around this by using
a computer simulation where we can vary the conditions
and explore what the outcome is. So here is a model, we’ve got in red the prey
running away from the predator, and in blue the predator approaching the prey. In the next two strides,
the predator is going to reach the prey. So in the first stride, the prey makes a decision to move. It can turn left or right or speed up or slow down, so
it can move anywhere in the red ellipse. The predator doesn’t know what the prey is going to do, so it carries on at the same speed, straight ahead. In the second stride, the prey can continue making
a second manoeuvring decision. The predator has sensed what the
prey is doing and will then react to that by attempting to capture the prey. The larger the area of the red ellipse covered
by the predator’s blue ellipse, the greater the chance the predator has
of capturing the prey. So you might think the prey’s strategy should
be to run as quickly as possible away from the predator. That is absolutely not the case. Because the predator is faster
and is catching the prey up. And actually, for the prey, it wants to be moving slowly because that gives
it a much greater range of options to outmanoeuvre the predator. It can turn, it can speed up, it can slow down, and it’s all about unpredictability. For the predator, it wants
the prey to be moving as quickly as possible and it doesn’t want to be moving much faster
than the prey. If the predator is moving very quickly, it makes it much harder for it to turn sharply, and that limits its ability to outmanoeuvre the prey. Here we’ve looked at the athlete –
the predator and the prey. What we see is very informative in terms of how athletic these species
need to be to survive, what the evolutionary arms race actually looks like at a biomechanical and locomotor perspective.

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  1. This is oversimplifying, instead of postulating a mathematical model they should've started with Kropotkin and his observations on hunting.

  2. This seems way too simple. Surely the research has to be significantly more complex than what the video portrayed?

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