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Can endangered Mexican wolves be conditioned to dislike the taste of sheep?

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

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Reintroducing critically endangered Mexican gray wolves (Canis lupus baileyi) to the U.S. Southwest has never been easy. It hasn’t helped that livestock owners hate the wolves. Every month livestock deaths that might have been caused by a wolf must be thoroughly investigated by the U.S. Fish & Wildlife Service (FWS). If any wolves are found to be a problem, they must be caught and returned to captivity. With only a few dozen of the predators left in the wild, every animal counts, and these removals hurt the long-range hopes for the species.

But now two psychologists have an idea to ease that human–wolf conflict: teach Mexican wolves that eating sheep will make them sick, so they stop predating on livestock.

Lowell Nicolaus, a biology professor emeritus at Northern Illinois University, and Dan Moriarty, a psychology professor with the University of San Diego, tried their idea in September 2009 with several captive Mexican gray wolves. According to a report published in the November 2010 issue of Monitor of Psychology, the researchers laced ground mutton with a nausea-inducing chemical called tiabendazole. The chemical has no taste or smell, so the wolves were not able to detect it. But after eating the contaminated meat, the sickened animals later refused to eat more sheep flesh.

Taste-aversion therapy has been tried before (like this experiment in Australia to teach endangered quolls not to eat cane toads), but it hasn’t been widely used in wildlife conservation. Moriarty says the FWS’s Mexican Gray Wolf Recovery Program is now reviewing the idea. “This could be a really effective tool, so it’s certainly worth considering,” Maggie Dwire, FWS assistant recovery coordinator, told the Monitor.

Once hunted into virtual extinction, the Mexican gray wolf is now the most rare gray wolf subspecies in North America. Only 200 Mexican gray wolves exist in captivity, along with a couple dozen in the wild—all of which are descended from just seven animals (probably the last of their subspecies) captured a few decades ago. A reintroduction program begun in 1998 has been much less successful than planned, and fewer than four dozen wolves—all heavily monitored—roam an area skirting the Arizona–New Mexico border.

In other Mexican gray wolf news a female wolf named Fern is currently on her way from the El Paso Zoo to a sanctuary in Washington State, where she will hopefully breed pubs to be released into the wild. Any young she produces will be sorely needed: four Mexican gray wolves have been found dead in Arizona and New Mexico since June, the most recent casualty a female, found on October 12. Although FWS has not disclosed the cause of this most recent death, the previous three slain wolves had all been shot, and the service is offering a reward for information leading to arrest of anyone who is responsible for shooting the critically endangered animals. All told, at least 31 Mexican gray wolves have been illegally killed since the reintroduction plan began in 1998.

Photo via Wikipedia

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  1. 1. mtrancher 2:19 pm 11/10/2010

    I have seen "aversion therapy" proposed in many forms like 60 years ago making an alcoholic ‘duffy’ or get sick after being forced to drink too much or presently using a drug to adversely react to alcohol. An electric fence or dog shock collar attempts to use the same aversion theory. My father’s "time out" method worked best on us growing up — he took time out of his busy day to whup our ass when we misbehaved!

    But regarding wolves following their instincts killing livestock, dogs, horses or eventually humans these ideas have great shortcomings. How will it be possible to apply this intensive conditioning to each new wolf as it enters the population? The enthusiastic wolf supporters should have these "remarkable social creatures" chewing on their assets and threatening their livelihoods while the solutions to their problems are researched; their attitudes would change, I am sure.

    The wolf problem in Montana, Idaho & Wyoming is a complex one with some practical solutions developing but the familiar extreme & unbending demands of the "environmentalists" destroys every workable plan that evolves. It is very frustrating to try to negotiate a solution with someone that has "no dog in the fight"!

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  2. 2. CaptainSakonna 12:03 pm 11/11/2010

    For my part, I find it frustrating to negotiate solutions with people who value profit over the lives of animals. I would willingly give up some of my assets (such as they are) if I had to kill a wolf or other higher animal that I didn’t intend to eat to save those assets. And you can’t say that wolf-lovers have "no dog in the fight" — the wolves are our "dog." They belong to the general public, so you can think of the wolves themselves as one of our assets; and we don’t want them shot just to protect some cattle or sheep that they’re following their natural instincts to prey on. As a consumer and a member of the public, I’d much rather have a healthy wild population of wolves than continue eating beef/mutton or wearing wool.

    In my opinion, ranchers need to realize that wolves are now part of the cost of doing business. They got a free pass during the years when wolves were exterminated, but those days are over. If wolves raise your expenses, pass some or all of them on to your consumers. Let the ones who raise and eat the beef pay for *all* its associated costs, instead of externalizing them on our wildlife.

    In any case, wolves are not a real threat to the ranching industry, nor are they highly dangerous to humans. They account for less than 1% of livestock losses. Domestic dogs kill far more livestock than wolves do, but I haven’t heard anyone suggest opening a hunting season on people’s pets. And livestock losses due to predation by any animal are dwarfed by losses due to severe weather, disease, and birthing issues. Wolf losses are a drop in the bucket, so stop harping on them and focus on protecting your animals from the problems that really matter. As far as killing humans goes, wolves are probably the least dangerous of all the large predators on the North American continent. In the past twenty years, we’ve seen at most two (there is dispute) wolf-caused fatalities in the US and Canada. For comparison, domestic dogs kill 20+ people in the US each year, and hunting accidents kill almost 100 people each year in the US and Canada.

    It’s not certain that hunting is an effective way to deal with human-predator conflict anyway. It breaks up established packs and leads to a greater proportion of young, inexperienced animals in the population; this can lead to additional conflicts with people as these inexperienced animals seek easy meals.

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  3. 3. jtdwyer 1:54 pm 11/11/2010

    The article states:
    "Only 200 Mexican gray wolves exist in captivity, along with a couple dozen in the wild–all of which are descended from just seven animals (probably the last of their subspecies) captured a few decades ago. A reintroduction program begun in 1998 has been much less successful than planned, and fewer than four dozen wolves–all heavily monitored–roam an area skirting the Arizona-New Mexico border."

    It seems highly unlikely that the entire population could be recaptured, intensively retrained to ignore their most basic feeding instincts, then successfully reintegrated into the ‘wild’ (you know, where the ranchers are raising sheep and children).

    As I understand, this small breeding population could not likely sustain itself simply because of its inadequate genetic diversity. They’re already gone.

    Also, as I understand, packs of domesticated dogs do not sustain themselves for long out in the ‘wild’. They fail and die out, but are continuously being replenished as dog lovers throw more of them out into the countryside…

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  4. 4. 9:01 pm 11/16/2010

    I am very glad to see that this article provoked some comment. Shows some folks care some about the issue. But the comments betray some real misunderstandings about the process of conditioned taste aversion and just how much practical field research supports it. So, for those of you interested in becoming informed about this very important process, please log on to my web site at: Strap in!


    Lowell K. Nicolaus, Ph.D.

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  5. 5. verdai 8:07 pm 11/17/2010

    Here we go again, Ahhh Jesus help us!
    Who is the top, man, wolf, or sheep? Is one closer to another than to itself?

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  6. 6. nogod 1:02 pm 12/12/2010

    The problem is that ranchers kill Mexican wolfs on sight. And for the record ranchers raise cattle not sheep. So conditioning wolfs to hate sheep is stupid. If one wants any success in the reintroduction of the Mexican Wolf then concentrate on making wolfs hate the taste of beef.

    The biggest hurdle is culture. There is a culture of Ranchers down here in the SW that will never accept wolfs as neighbors. 31 Mexican wolfs died from gun shot wounds. Obviously the government didnt take the ranchers seriously when they asked for public comments and the ranchers said they would kill all wolfs on sight. Which they are doing at the expense of the wolfs and tax payers money.

    I think its time to admit that the reintroduction of the Mexican wolf is a failure. Time to try something different you know maybe something that will work.

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