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