Locomotion dynamics of hunting in wild cheetahs

1. What they did

The cheetah is known as the fastest land animal, but almost nothing was known about how wild cheetahs actually move when they hunt. Earlier measurements came from captive cheetahs chasing a lure in a straight line, or from watching and filming wild cheetahs in open country by day.

The researchers designed and built their own collar, about 340 g, similar in size and weight to a normal wildlife collar. It combined a Global Positioning System (GPS) unit, recording position and speed five times a second, with an inertial measurement unit (IMU): accelerometers, gyroscopes and a magnetometer that sense the body’s movements up to 300 times a second. Solar cells charged the battery. The collar watched the cheetah’s activity all day and switched to full recording when a run started.

They fitted the collars to five wild adult cheetahs (three females, two males) in the Okavango Delta region of northern Botswana and recorded 367 runs over 17 months, most of them hunts. Combining the GPS and IMU data gave each run stride by stride: speed, acceleration, slowing down, turning and power.

A run was classed as a successful hunt when the activity data showed about 6 minutes of feeding in the 30 minutes after it. They checked this method against hunts with known outcomes and field observations. They also tested the collar on a dog running on a beach, comparing it with footprints in the sand mapped by survey-grade GPS and with high-speed video.

2. What they found

Speed and distance

• The fastest run reached 25.9 m per second (93 km per hour, 58 miles per hour), averaged over a stride. The other four cheetahs’ top speeds were 25.4, 22.0, 21.1 and 20.1 m per second.
• Most hunts used only moderate speeds: the average top speed was 14.9 m per second, usually held for only 1 to 2 seconds.
• Runs averaged 173 m; each cheetah’s longest run was 407 to 559 m.
• The cheetahs ran about 1.3 times a day, so high-speed running was only a small part of the 6,040 m they travelled on an average day.
• The male Qamar, who often hunted in thicker vegetation, never ran faster than 20.1 m per second and was often seen on warthog kills.

Success, habitat and time of day

• 94 of the 367 runs (26%) were successful hunts. Including 530 more runs found only in the activity data gave the same rate (25%). This is lower than earlier reports, perhaps partly because some runs were play or running from larger predators, which could not be reliably separated from hunts.
• 48% of runs were in open grassland, 28% in open shrub or around large trees, and 24% in dense vegetation. Individual cheetahs differed in where they ran.
• 20% of runs in open grassland were successful, compared with 31% in dense cover. This difference was not significant, but it shows cheetahs do hunt successfully in all terrains.
• Almost half the runs were at or after dawn, but runs happened throughout the day and night.

What made a hunt succeed

• Successful hunts involved harder braking (deceleration) on average. Peak acceleration, distance, number of turns and total turning angle did not differ significantly.
• This suggests the outcome is decided in the final stage of a hunt, rather than hunts being given up early.

Acceleration, braking and power

• The cheetahs could speed up by up to 3 m per second, and slow down by up to 4 m per second, in a single stride.
• Their greatest acceleration and braking were almost double those published for polo horses. Their power often exceeded 100 watts per kilogram of body mass, compared with 25 for Usain Bolt’s 100 m world record, 30 for polo horses and 60 for racing greyhounds. Braking was even more powerful than accelerating.
• The wild cheetahs were heavier and more muscular than captive cheetahs (53 kg against 33 kg on average, with thicker thighs). Their main driving muscles have longer leverage than a greyhound’s, which, like a car in a lower gear, lets the muscles work fast and deliver great power.

Turning and grip

• Hunts involved a lot of manoeuvring. Sideways (cornering) acceleration often exceeded 13 m per second per second at speeds under 17 m per second, more than double that of polo horses. Such turns need very good grip; the cheetah’s ridged footpads and claws act like the cleats on sports boots.
• Cheetahs did not make tight turns at their highest speeds, and did not brake or accelerate hardest at the same time as turning hardest.
• They often slowed sharply before turning. At 25.9 m per second, a cheetah would need about 6 seconds to turn around; slowing from 16 to 4 m per second, which takes three strides, shrinks the turn radius from 19.7 m to 1.2 m.

3. What they concluded

• This is, as far as the authors know, the first detailed record of how a large running predator moves while hunting in the wild.
• Wild cheetahs reach remarkable top speeds, but most hunts are run at moderate speed. What sets cheetahs apart is their acceleration, braking, power and agility.
• Slowing down before turning is valuable: a cheetah chasing agile, quick-turning prey should run little faster than the prey in the final phase, and peak speed was not a feature of the end of successful hunts.
• Grip and manoeuvrability are key to hunting success. The cheetah’s crouched posture when braking, flexible spine and tail likely help control the body during sharp turns.
• Similar data for other wild running species would add to what is known about natural speed, agility, endurance and movement in the wild.

6. Other technologies, skills or innovations

• A custom-built, solar-powered collar combining GPS (5 readings per second) with accelerometers (300 per second), gyroscopes and a magnetometer. It changed between operating “states” (sleep, alert, mooch, ready, chase) by time of day and activity to save power, and buffered the last few seconds of accelerometer data to catch the start of a run.
• Data were downloaded by radio to a vehicle or light aircraft every few weeks, and new settings and software could be uploaded while the collar was on the animal. A very high frequency (VHF) radio transmitter allowed the cheetahs to be found.
• Fusing GPS and IMU data cut the typical position error from 5.05 m to 0.67 m and the speed error from 1.23 to 0.34 m per second.
• Hunts and feeding were identified from accelerometer patterns alone; this method correctly identified nine of ten known successful hunts and agreed with other signs of success (prey struggling, the cheetah staying at the site over two hours, or a cheetah seen on a kill) in 97% of known hunts.

7. Implications for conservation (from the paper)

• Fine-scale data showing where endangered animals commute, hunt and rest would help in assessing landscape connectivity, wildlife corridors and protected areas.
• Detailed data on hunting places could show why cheetahs prefer certain hunting habitats, and how habitat affects their risk of injury (very important for solitary predators), their risk of being detected by kleptoparasites (animals that steal kills) in open versus closed habitat, and their own risk of predation.