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When the heat is on, the cheetah is cool.

running-cheetahrunning-cheetah

A COLLABORATIVE STUDY BY THE UNIVERSITY OF THE WITWATERSRAND, SOUTH AFRICA, THE UNIVERSITY OF WESTERN AUSTRALIA AND THE AFRICAT FOUNDATION, NAMIBIA:

Why Do Cheetahs Give Up the Hunt? It’s a Myth That Cheetahs Overheat While Hunting -

ONE of the most prevalent myths in animal biology has been debunked, with scientists proving cheetahs don't abandon hunts because they overheat.

- Cheetah hunt theory disproved - Cheetah Agility More Important Than Speed - When the heat is on, the cheetah is cool - Long-Held Myth About Cheetahs Busted:

HEADLINES ACROSS THE GLOBE ABOUT RESEARCH DONE AT THE AFRICAT FOUNDATION:

According to new research, the fastest land animal on Earth depends on more than speed to catch its prey. In order to successfully hunt, cheetahs need to be genetically strong, able to slam on the brakes, turn quickly and stay fit. For superb athletes, cheetahs are surprisingly poor hunters with up to 60% of hunts ending in failure. In a race over 100m, a cheetah would beat Usain Bolt by 60 meters and easily could outsprint any anthelope. But they often give up the sprint when within easy reach of their prey?

So what happens in a real hunt? Answering that question had to wait until research could measure body temperature of hunting cheetahs. Researchers from the Brain Function Research Group at the University of the Witwatersrand in Johannesburg, SA - working with Professor Shane Maloney of the University of Western Australia, develop the technology needed.
"But that wasn’t enough." said Professor Andrea Fuller, the group Director. "We needed conservators who were committed to advancing cheetah research." The Group found those conservators at The AfriCat Foundation, based in the private, Okonjima Nature Reserve in central Namibia.

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AfriCat became part of a Thermoregulation study of free-living cheetah during 2005/2006 - the results are finally out and being spoken about around the globe!

To date, no one had investigated how wild cheetahs regulate their body temperature or how they deal with the extreme heat loads to which they are exposed. Hence the purpose of this study was to establish:

  • How cheetahs deal with environmental thermal stress
  • Whether the duration of a cheetah’s sprint is thermally limited.

As journalist 'Ed Yong' put it; "Data showed that their body temperature naturally fluctuates between 37.3 and 39.5 º C over the course of the day, and hunting doesn’t change that. Despite their enormous speed and acceleration, they barely get any hotter while sprinting. And while they finished successful hunts with an average body temperature of 38.4 ºC, they finish unsuccessful ones at 38.3 ºC. That’s a definition of 'over-heating' that I’m unfamiliar with.

Clearly, cheetahs don’t give up because of heat. They do, however, heat up more if they actually catch something. In the 40 minutes after they stopped, their temperature rose by 0.5 ºC if they had flubbed their chases, but by 1.3 ºC if they made a kill.
This wasn’t due to ambient temperature, the length of the chase, or how fast the cheetahs ran. It wasn’t due to the act of killing, since that only takes 10 minutes. It wasn’t due to energetic eating either, since cheetahs take a long rest before tucking into their prey."

 

Six cheetahs (Mo, Dewey and a group of four siblings - Artemis, Athena, Apollo and Zeus) underwent surgery in September 2005. A temperature-sensitive data logger (measures and records body temperature) was placed in their abdominal cavity, whilst a movement-sensitive data logger (records activity) was placed on their outer thigh, just beneath the skin. Each cheetah was also radio-collared, to allow for behavioural observations and to monitor their movements and health.
The cheetahs were then released into the then 11 300 acre, AfriCat|Okonjima, Tusk Trust Rehabilitation Park, where they remained for 6 months.
In May 2006 the data loggers were removed and their data retrieved.
A weather-station measured the environmental conditions that the cheetahs were exposed to. Variables such as air temperature radiation, wind direction and velocity, and rainfall were also taken into account.

running-cheetahcheetah collar 

In 1973, researchers thought they had figured out why cheetahs give up the hunt. The idea came about from a single historic study of two tame cheetahs on a treadmill. It has been perpetuated by safari guides, natural history media and even student textbooks. When they put the big cats on a treadmill, the animals stopped running after their body overheated, reaching temperatures of 40.5°C.

The problem was that the speed that the treadmill could reach was nowhere near that of a real hunt. The cheetahs ran at a maximum speed of 30km/h and stopping within about 2km. The study concluded running cheetah stored metabolic heat so that further exercise soon became impossible at a maximum temperature of 40.58 ºC.

But scientists at University of Western Australia and the University of the Witwatersrand in South Africa wanted to know what happened in a real hunt? In actual hunts, cheetahs can sprint at more than 100km/h and typically traverse less than 300 metres.
They found body temperature did not rise significantly during the chase. Although cheetahs can sprint faster than any of their potential prey, they abandon most of their hunts, with less than 40 per cent ending in kills.

This new research has now proven that a cheetah's body temperature does not significantly rise during the chase, but increases on average 1.3°C after a successful hunt and 0.5°C after an unsuccessful one. The team speculates that this temperature spike could be stress-related as the cheetahs keep on the lookout for more dominant predators such as lions and leopards looking to snatch their dinner. . (Two cheetahs were killed by leopards during the study.) "Body temperature exceeded the 40.58C ceiling seldom and far less often when the cheetah abandoned hunts,"
Research veterinarian, Dr Leith Meyer, confirms that he has seen similar increases in the antelope body temperature when they are stressed.
Still, no one knows why the quick cats throw in the towel on most of their chases?! "Whether hunts induce a higher core temperature in cheetah using open-pursuit hunting patterns in grasslands or in cheetah exposed to hotter environments, remains to be investigated."

thermoregulation study
(download PDF here)

 

SO, CHEETAHS DO ABANDON HUNTS BUT NOT BECASUE THEY OVERHEAT, AND A THEORY THAT HAS BEEN IN NATURAL-HISTORY BOOKS FOR 40 YEARS - IS A MYTH.

It's going to allow us for the first time to understand what any species is doing in its stride-by-stride activity," says David Carrier, a comparative biomechanist at the University of Utah in Salt Lake City who was not involved in the work. "This is a big step forward in terms of understanding what animals do in the real world."

running-cheetah dewy on a kill

Of course, none of this explains why cheetahs abandon chases early.
Perhaps Alan Wilson’s work  (Alan Wilson biography) might eventually provide an answer, using the astonishing collars (Collars reveal just how extreme cheetahs can be.) - he developed to track the movements of wild cheetahs. These same collars helped to check another cheetah factoid—the idea that they can actually hit top speeds of 100 km per hour. That was also based on a single artificial study, but to the relief of cheetah fans everywhere, it turned out to be right. Wild cheetahs do actually get very close to that speed when they hunt.

 

We’ve been fascinated recently by how much of our natural history consists of similar barely-substantiated claims that have only been recently tested. Some turn out to be true, like the cheetah’s speed or the function of the thresher shark’s tail (Thresher sharks hunt with huge weaponised tails). Others are myths, like the cheetah’s heat problems, or the komodo dragon’s bacterial bite (they use venom) (The myth of the Komodo Dragon's dirty mouth.), or the honey badger’s partnership with honey guides (Lies, damned lies, and honey badgers.) (deceitful documentary-makers), or the suicidal tendencies of lemmings (deceitful film-makers). One wonders what other myths will be busted in coming years.

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SPECIAL THANKS TO ROBYN HETEM from the University of Witwatersrand in South Africa for getting this project back on track and published!
http://www.wits.ac.za/academic/health/physiology/researchunits/bfrg/staff/9065/robynhetem.html

 

Cheetahs may be the world's fastest land animal, but they give up about 60% of their chases: http://news.sciencemag.org/sciencenow/2013/06/cheetah-agility-more-important-t.html?ref=hp

 

Collars Reveal Just How Extreme Cheetahs Can Be: http://phenomena.nationalgeographic.com/2013/06/12/collars-reveal-why-just-how-extreme-cheetahs-can-be/

 

Speedy cheetahs put through paces: http://news.bbc.co.uk/2/hi/science/nature/8137962.stm

 

When the heat is on, the cheetah is cool: http://www.wits.ac.za/newsroom/newsitems/201307/20806/news_item_20806.html and http://rsbl.royalsocietypublishing.org/content/9/5/20130472

 

It’s a Myth That Cheetahs Overheat While Hunting: http://phenomena.nationalgeographic.com/2013/07/23/its-a-myth-that-cheetahs-overheat-while-hunting/

 

Cheetahs on the Edge: http://ngm.nationalgeographic.com/2012/11/cheetahs/smith-text

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