Johannesburg - When it comes to cheetahs, it turns out that speed isn’t everything.
Instead, the cats adapt their hunting techniques depending on the prey they’re after, says a new study published this month in the Royal Society’s journal Biology Letters.
The findings come after a six-year study on the cheetahs living in the Kgalagadi Transfrontier Park, where scientists were looking to how well adapted the animals were to living in the arid Kalahari.
When it comes to the world’s fastest land animal, the fascination is always with speed.
But ecology and energetics specialist Dr Michael Scantlebury, from Queen’s University Belfast, had a different question.
“What are the energy costs of a hunt?” he asked. “How fast must a cheetah go? How much effort must they put in to catch their prey?”
To calculate this, the team attached collars to the cheetahs. On each collar was a GPS, capable of measuring where a cheetah was at intervals of less than a second: this would measure the animal’s hunting track.
But the collars also had accelerometers, measuring not only how fast a cheetah was accelerating, but its orientation: how it was twisting and turning its body during a chase – much like the sensors in some phones flip the screen when rotated.
What they found was surprising.
“We always believed that cheetahs basically see their prey, run fast, catch it and kill it,” said South African co-author Dr Gus Mills, from the Lewis Foundation, who physically observed the hunts.
He had been hoping to show how fast a cheetah can go. Previous measurements were taken in set-up situations; a cheetah’s sprint has never been recorded in the wild.
“What we were surprised by was that the cheetahs don’t run so fast,” said Mills.
By comparing Mills’s field notes with the collar recordings, the team realised it’s not enough to be fast.
“Like a bull fighter in a ring, prey can just step to the side to avoid a predator,” explained Scantlebury. “The predator then wastes time coming back around, giving the prey a chance to escape.”
So the cheetahs couldn’t just charge their targets at high speed. Instead, the hunt was broken down into two parts.
First, the cheetah accelerated rapidly, narrowing the gap between its intended prey.
But then it slowed down. You can’t turn quickly at high speeds, so as it gets closer to its prey, a cheetah trades speed for agility, mimicking the prey’s darting escape tactics.
This slowing-down period is prey-specific: for more darting, agile animals like ostriches and hares, they slowed down more. For the larger prey who did not jink as much, such as gemsbok, they slowed down less.
It explained why the speed measurements were lower than expected: the cheetahs were compromising their speed according to the behaviour of the prey.
Throughout the hunt, the amount of energy the cheetah is using stayed relatively constant, “like a car engine running at constant revs”, said Scantlebury.
Just as the prey had evolved different escape strategies, so had the cheetah’s hunting tactics evolved.
The team will continue writing up the findings of their six-year study.
“The more we understand about the physiology and hunting tactics of this charismatic animal, the more we are able to ensure its continued existence,” said Scantlebury. - The Star