The dark side of the human shield effect in animals that avoid larger predators

2023-05-23 12:15:51

Medium-sized carnivorous species (mesopredators such as coyotes or bobcats) tend to move to human-dominated areas to avoid predation by larger carnivores, a phenomenon also known as the “human shield” effect.

While the use of human shields has been linked to increased wildlife survival rates in some cases, it also has the potential to impose an increased risk of human-caused mortality through hunting or collisions with vehicles, among other causes.

However, until the new study, little was known about this negative potential of human closeness for medium-bodied predators.

Using data from coyotes and bobcats (mesopredators), as well as wolves and pumas (large carnivores) from the same area, Laura Prugh of the University of Washington in Seattle, US, and her colleagues investigated the movements of these animals. each other and in relation to major human activities in northern Washington state.

Prugh and his colleagues found that medium-sized predators tended to move away from larger ones toward areas with greater human influence, suggesting that medium-bodied species perceived humans as less of a threat than larger carnivores. .

A coyote photographed at night. (Photo: USGS)

However, the study authors found that instead of protecting mesopredators and improving their overall survival, human-caused mortality rates for mesopredators were more than three times higher than mortality caused by large carnivores in these areas. areas.

Prugh’s team suggests that this scenario could represent an ecological trap.

The study is titled “Fear of large carnivores amplifies human-caused mortality for mesopredators”. And it has been published in the academic journal Science. (Source: AAAS)