A “Super-Predator” Terrorises All Continents

Mammals worldwide have developed unique strategies to survive by adapting to their diverse habitats. However, at the heart of these strategies is a simple but powerful emotion: fear. Fear is a defence mechanism that allows animals to survive by anticipating danger. Even the sounds of predators are powerful stimuli that drive animals to flee in the face of danger.

If we were to go to different corners of the world and ask animals about their greatest fear, they would probably run away before we could get an answer. That is the real answer. Research shows that animals are scared of human voices in Africa, Asia, Europe, North America, and now Australia. When they hear human voices, animals feel the threat of a “super-predator” and either flee or remain vigilant.

Humans kill animal species at much higher rates than other similar predators, and it is for this reason that we are considered “super predators.” The environmental impacts of human activities are diverse, ranging from habitat destruction and pollution to the spread of invasive species, overuse of resources, and climate change. This suggests that the “fear of humans” is not entirely unjustified.

A study in the Greater Kruger National Park in Africa found that carnivores and ungulate species (such as giraffes, leopards, hyenas, zebras, rhinos, and elephants) are twice as likely to flee when they hear human voices compared to lion sounds. The magnitude of this fear has been observed in similar experiments carried out in Asia, Europe, and North America, where carnivores and ungulates as diverse as cougars, European badgers, fallow deer, white-tailed deer, and wild boars were twice as likely to flee when they heard human voices compared to those of leopards, cougars, bears, dogs, or wolves.

Ecologist Katherine McGann from the University of Tasmania set out with her colleagues to determine if a similar fear is common among the marsupial mammals of Australia.

To experimentally test whether Australian mammals fear the human “super-predator,” the team studied four native marsupial species (eastern gray kangaroo, Macropus giganteus; Bennett’s valabis, Notamacropus rufogriseus; Tasmanian pademelon, Thylogale billardierii; and the common brush-tailed possum, Trichosurus vulpecula) and the recently introduced fallow deer (Dama dama). They observed how these species responded to calm human speech, the barking of dogs, the growls of the Tasmanian devil, and the howling of wolves.

Australia’s land mammal fauna is known for its atypical antipredator behaviour because it is the world’s largest island. Until recently, studies have suggested that the lack of large mammals in Australia has led to naive or incomplete responses of its mammals to certain predators.

However, for the last 50,000 years, Australia has had an extremely dangerous “large mammal predator”: humans. Archaeological findings have revealed that all four marsupials in Tasmania have been hunted by humans for thousands of years. Today, eastern grey kangaroos are protected in Tasmania, but they were hunted to near extinction in the 1950s for human consumption and as dog food. Thousands are still shot each year to protect crops. Other marsupials are also allowed to be hunted for commercial and sporting purposes, and at least one million marsupials are killed each year for crop protection

The 684 videos recording the reactions of marsupials exposed to sounds showed they were at least 2.4 times more likely to flee when they heard human sounds compared to dog sounds, to which they were the second most responsive. The fallow deer, like the marsupials, also responded to human sounds, but not more than they did to other species. The team attributes this to the fact that Tasmania’s fallow deer were introduced to the region relatively recently and are descended from a small population that had been in captivity for a long time.

The “invisible” influence of humans in the natural world and their role as predators have profound and far-reaching impacts on ecosystems. From carnivores to ungulates and rodents to plants, the chain effects of fear from humans can shrink animal populations for generations and have unexpected results on ecosystems.

However, this fear can be turned to our advantage in conservation efforts. For example, human voices are effective in reducing crop damage caused by deer and in keeping rhinos away from areas at the highest risk of poaching. McGann and her colleagues recommend using recordings of human voices to help protect crops and reduce damage to native plants.

Human presence in nature has profound and far-reaching impacts on wildlife. Recognising these impacts, we must continue our efforts to improve conservation and management strategies and build a more harmonious relationship with the natural world. With this in mind, understanding the fear of humans and using it as an effective tool in conservation strategies can help us build a better future in harmony with nature.