It was a slaughter. By 2007, a family of pumas likely killed thousands of Magellanic penguins (MP), over the course of several nesting seasons along the wild coastline of Argentine Patagonia.A group of scientists scoured the Monte Len National Park crime scene, collected information, and have now presented some theories about the root causes of this seabird mass murder. They have also named some unwitting co-conspirators behind the killings: humans, according to an article in the Journal for Nature Conservation.A Significant Penguin PopulationAbout 100 years ago, the Patagonian penguin population was probably not nearly as large as it was in 2007. That began to change when sheep farmers arrived, and, to protect their flocks, probably killed off most potential penguin predators. Growth in both whaling and the fur trade there probably had a similar effect on marine predators.This would have made breeding habitats near marine food resources accessible and may have also reduced competition with neighboring colonies, according to the paper.Most seabird species avoid such fates by choosing to live in safer neighborhoods. Predator-free islands and hard-to-reach-cliffs and capes offer natural protection.The paper notes that a significant number of large MP colonies ignored that rule. Once the land and sea of Patagonia was cleared of predators, there was less need for the sea birds to find more protected homes. Motives for PumasThe scientists examined radiocarbon dating of colonies, along with historical and archaeological records to reach their conclusion. Penguin colonies likely grew massively over the hundred or so years after their predators were eradicated.While records regarding the status of the MP population and colony locations prior to the terrestrial top predator eradication are scarce, compelling evidence suggests that the present location of colonies in the continent and population size may have undergone substantial changes due to the eradication of mammalian predators, the paper notes. The motive still remains unclear. Pumas are not generally known to eat penguins. And many of the sea bird bodies found within the park were clearly killed but not consumed. Conservation DilemmaThis case presents a philosophical paradox in terms of penguin conservation, the paper concludes.What should we do when human intervention, like the eradication of terrestrial predators, benefits charismatic species like penguins but comes at the expense of less charismatic natural resources? according to the study.That is a mystery that remains unsolved.Article SourcesOur writers at Discovermagazine.com use peer-reviewed studies and high-quality sources for our articles, and our editors review for scientific accuracy and editorial standards. Review the sources used below for this article:Journal for Nature Conservation. Consequences of terrestrial top predator control by Patagonian sheep farmers for coastal marine food websBefore joining Discover Magazine, Paul Smaglik spent over 20 years as a science journalist, specializing in U.S. life science policy and global scientific career issues. He began his career in newspapers, but switched to scientific magazines. His work has appeared in publications including Science News, Science, Nature, and Scientific American.