There is something majestic and beautiful about apex predators. When we took our sons to a zoo or a wild animal preserve during their childhood years, the first animals they wanted to see were lions, tigers, bears, and wolves—the animals at the top of the food chain, what zoologists refer to as apex predators. Two field research studies, one done in Australia and the second done in Rocky Mountain National Park, and a published critique of these studies add to a growing body of evidence demonstrating that apex predators have value and purpose far beyond their aesthetic appeal to humans.
Apex predators prey on the top herbivores. However, the top herbivores are also a big attraction for humans. Young children and adults are enamored of these magnificent creatures. For example, the buffalo, moose, and elk of Yellowstone National Park draw visitors from all over the world. So great was this tourist draw that for several decades Yellowstone Park officials protected these megaherbivores from wolves and grizzly bears.
Yellowstone research biologists recently persuaded reluctant park officials and even more reluctant neighboring ranchers to allow a limited reintroduction of grizzly bears and wolves. The presence of these apex predators has resulted in Yellowstone’s top herbivores avoiding any significant grazing along Yellowstone’s river and stream banks. This avoidance behavior has led to the recovery of willows, and the recovery of willows has resulted in a minor population explosion of beavers and beaver dams. The return of a much larger beaver population to Yellowstone has had wide-ranging benefits for the entire ecosystem. In two previous articles (here and here), I described and documented these benefits and how beavers and their dams and lodges enhance human civilization in other ways.1
The Australian field research study monitored the impact of an apex predator (wild dingoes) on mesopredators (feral cats) and the mesopredators’ prey (desert rodents).2 These researchers observed that the introduction of wild dingoes into a habitat region increased the population of desert rodents. They further showed that the cause of the population increase was not just due to less predation by feral cats; they noted that the rodents increased their habitat breadth and the use of risky food patches.
Both the Yellowstone and Australian field studies have received criticism from other research groups for being overly simplistic and biased toward the larger animals and plants. In a review published in Nature, Emma Marris argues for combining bottom-up and top-down approaches to assessing ecological benefits and detriments.3 Bottom-up refers to analyzing how the small-bodied life-forms impact progressively larger bodied life-forms, while top-down analyzes how large-bodied life-forms impact progressively smaller bodied life-forms.
Marris and the studies she cites conclude that ecological relationships are extremely complex, with a single species impacting several dozen or more species rather than just two or three. They note that if the full complexity of the relationships is not taken into account and understood, human intervention could result in diminished benefits or unintended detriments.
One published example of diminished benefits of human intervention is a field study done in Rocky Mountain National Park.4 The researchers compared two efforts to address elk overgrazing: (1) where humans in Rocky Mountain National Park culled elk and fenced off riparian environments, and (2) where in other parks wolves were reintroduced into the environment. The researchers noted that wolf reintroduction yielded superior results.
Another research report uncovered at least one reason why wolf reintroduction resulted in a superior outcome.5 They observed that prey animals respond differently to their natural predators than they do to humans. In particular, the fear response that the prey animals had to wolves had a much more dramatic impact on the behavior of the prey animals, and this behavior change had ripple effects that benefited a wide diversity of animal and plant species.
All of this new ecological research is teaching us just how remarkably complex and well-designed natural, unspoiled ecosystems are. The fact that even our best efforts as ecosystem managers fall short in producing benefits shows us that Someone far more knowledgeable, intelligent, and powerful than us must be the One who established the ecological relationships in the first place. This conclusion is confirmed by the consistent observation that the mass speciation events that follow the mass extinction events seen in the history of Earth’s life reveal that ecological optimization appears immediately. I describe and document much more about this consistent pattern of ecological optimization and why it is necessary for human civilization to be possible in my new book, Improbable Planet.6