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Lions vs. Cattle: Taste Aversion Could Solve African Predator Problem

The views expressed are those of the author and are not necessarily those of Scientific American.


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After coexisting for thousands of years, humans and African lions (Panthera leo) are on a collision course. Lion populations have dropped from 450,000 animals 50 years ago to as few as 20,000 today. Most of that decline has taken place over the past two decades, and experts are now predicting that the big cats could actually go extinct in as little as 10 to 20 more years.

Threats to lions come on many fronts—including hunting by American trophy seekers, poaching for use in traditional Asian medicine, disease and pesticide poisoning—but the biggest danger occurs when lions encroach upon livestock. Cattle farms have taken over much of the African savanna and grasslands, thus pushing aside lions’ natural prey such as impalas, zebras and buffalo. Rather than following the prey to new territories, many lions simply turn to its nearest replacement—cattle. But when lions kill cattle, it affects peoples’ livelihoods, and the lions are the ones that often end up paying the price with their lives as farmers shoot or poison the troublesome beasts.

But now there’s an idea that could keep lions from predating on livestock. The Colorado-based nonprofit WildiZe Foundation has funded research to see if lions can be taught to dislike the taste of beef. The process is called conditioned taste aversion, and it has worked with some other endangered species, including Mexican wolves and quolls in Australia.

Denver Zoo research associate Bill Given started his research on lions this September at Grassland Safari Lodge in Botswana. The lodge is home to several lions that have previously slain cattle but were captured by lodge personnel before farmers could kill them. The lions now live semi-wild lives in 11-hectare enclosures at the lodge but depend upon humans for their food. Given and his team of researchers gave eight of the cats meals of beef treated with the deworming agent thiabendazole in doses large enough to make them temporarily sick to their stomachs. “It basically causes a bad case of indigestion,” WildiZe founder Eli Weiss told The Aspen Times.

After a few meals of treated beef, the lions were once again offered untreated meat. Seven of the eight refused to eat it, while an eighth actually refused to eat at all for a short period.

Writing for the WildiZe Web site, Given described conditioned taste aversion as “a natural defensive mechanism enabling predators to survive encounters with prey with toxic [antipredator] defenses. When mammalian predators experience nausea after consuming prey with toxic defenses, they form an aversion to the taste and scent of these prey animals. Long after recovering from the effects of a [sublethal] dose of the toxin, predators avoid offending prey wherever they are encountered.”

Now that researchers know conditioned taste aversion works in lions, the next step is to obtain approval from Botswana’s Department of Wildlife and National Parks and the Kenya Wildlife Service to try the idea in the wild.

Photo by Dominik Kreutz via Flickr. Used under Creative Commons license

John R. Platt About the Author: Twice a week, John Platt shines a light on endangered species from all over the globe, exploring not just why they are dying out but also what's being done to rescue them from oblivion. Follow on Twitter @johnrplatt.

The views expressed are those of the author and are not necessarily those of Scientific American.





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  1. 1. Jerzy New 8:26 am 12/28/2011

    The piece starts with untruth that lion population was “450,000 animals 50 years ago”, followed by another that “experts are now predicting that the big cats could actually go extinct in as little as 10 to 20 more years”.

    Give source of these claims. Lion populations 50 years ago are at best very unclear guesstimates, and no serious expert predicts lion extinction so fast (what would vaporize thousands of lions in well protected South African reserves and zoos?)

    I am disappointed with low quality of Scientific American blogs. Search me why it would persuade me to buy the paper magazine. Why should I pay to be fed alarmist environmentalist propaganda masqueraded by references to “experts” and “scientific”?

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  2. 2. vdinets 11:37 pm 12/28/2011

    Jerzy: Myers (1975) wrote, “Since 1950, their [Lion] numbers may well have been cut in half, perhaps to as low as 200,000 in all or even less” (I’m quoting from IUCN web page for P. leo). So the estimate of 450 kilolions in the 1960-s is probably not that improbable. As for extinction within 10-20 years – you are right, that’s total bullshit.

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  3. 3. John R. Platt in reply to John R. Platt 5:09 pm 01/5/2012

    It probably depends on the country, but many lion populations are in freefall. The Kenya Wildlife Service itself acknowledged that the rate of attrition in that country could wipe out all lions within 20 years, and that was two years ago. http://lionguardians.wildlifedirect.org/2009/08/20/kenyan-lions-face-extinction-in-20-years/

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  4. 4. wildize 4:52 pm 01/6/2012

    In every country of their former range, wild, free-ranging lion populations have plummeted, with 90% of that decline over the past 20 years. The statement of lion extinction within 10-20 years is not whimsical. If wild population numbers cannot be stabilized within 5-10 yrs, meaning sustainable and viable reproductive health and increase numbers, no matter which country, then it is certainly possible that this iconic species will not be found in the wild. These population numbers do not include those lions in captivity- eg. zoos and animal parks, as they are typically captive bred and in most cases cannot be returned to the wild. The CTA trials are a critical and important tool toward mitigating conflicts between human/ livestock vs wildlife conflicts combined with the myriad cascade of consequences facing this IUCN threatened species. 20 years ago, the lion was not on the Red List.. today, it is. If you would like more information please visit http://www.wildize.org to learn more.

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  5. 5. John R. Platt in reply to John R. Platt 5:13 pm 01/6/2012

    Thanks very much for the comment and detail! People seem to cover their ears when they hear that lions are in danger of extinction. Now is the time to get people listening to this sad and scary truth.

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  6. 6. wildize 7:34 pm 01/6/2012

    Thank you. We can cover our ears, and bury our heads when it comes to species decline or climate change (a major cause), but it does nothing to address or change the fact that our earth’s bio-diversity is facing serious challenges. Our ecosystems are the foundation of the ‘free services’ or, embedded resources, this planet provides for our support- human, plant and animal- from the global to the trophic to the micro levels. When an apex, or keystone species is removed from the system, the biodiversity up and down the scale is affected. When apex or keystone predators are removed, the effects are exponential, as they act as the drivers and architects of our earth’s systems. Then of course, there is the psychological and emotional benefit to people in knowing there is ‘wildness’ out there. That, further, is offset in who must bear the cost of living with that wildness in your backyard. Species loss is not a linear equation. Like Friedman’s ‘global weirding’, one also must investigate the economic repercussions in the advent of the collapse of a wildlife based tourist industry- go to Africa and not see a wild lion?That collapse alone will have far ranging consequences whether or not we care about the aesthetic of wildness and lions. Lions are the icon of wildness and wilderness as polar bears are of the arctic, but ] somehow more accessible. What can we say about ourselves if we choose to ignore the evidence and do nothing to protect this magnificent species…. before it goes extinct?

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