Psychology Today: Healthy Ecosystems Need Fear
Gorongosa was once a celebrated and species-rich national park. But a decades-long civil war ending in the 1990s decimated the park’s large wildlife.
While GPS-collaring and tracking the antelopes of Gorongosa, Pringle noticed that a species called bushbuck was no longer hiding in the bush.
“Everything we know about bushbuck says they are forest-dependent antelope confined to woodland and thicket habitat,” he says. “These bushbuck were venturing out onto the wide-open floodplain, sometimes to areas miles from the nearest tree”
Pringle thought this aberrant behavior could be linked to two critical elements missing from Gorongosa: large predators and the fear they instill.
The traditional view of how predators affect ecosystems measures their influence by the animals they kill and consume. According to more recent theories, this view underestimates the total impact of predators.
The idea is known as the ‘landscape of fear’—the mere presence of predators inspires wariness in prey and changes their behavior, with repercussions that spread through the ecosystem.
Last year, Pringle and his colleagues reported how bushbuck brazenness has altered the park’s vegetation. The researchers confirmed that, in the absence of predators, bushbuck were leaving their comfort zone in search of more nourishing food. DNA analysis of bushbuck scat revealed that the animals were heavily feeding on the legumes and forbs on the open plain. By fencing off a section of the plain to exclude bushbuck, Pringle and his colleagues verified the toll the grazers were taking on the vegetation.
And it wasn’t just bushbuck changing their diets. In a healthy ecosystem, the herbivores have different, specialized diets. In Gorongosa, the herbivores’ diets shifted and overlapped, resulting in competition for the same food.
“If you give these systems a little bit of space and breathing room, we are discovering they are actually very good at repairing themselves”
