Carnivores, i.e. meat-eating animals, comprise 245 species, 31 of which are considered “large carnivores” because their body weight is above 15kg (≥ 33 lbs.). They are mostly positioned at the top of the food web, meaning they affect many species below them by feeding on them. 19 of those 31 carnivore species are considered threatened by the World Conservation Union (IUCN), and most species keep declining in range or numbers.
Large carnivores like wolves, bears, or tigers experienced massive declines worldwide in the past two centuries. Local extirpation of large carnivores has far-reaching consequences for natural ecosystems and can have unexpected repercussions on the balance of our planet. While human interactions with carnivores are often characterized by conflict, particularly for livestock herding communities, carnivores can also have positive effects on local economies and human well-being. To maintain keystone functions of large carnivores in ecosystems, conservation approaches need to be expanded to combine human and ecological dimensions in an integrated strategy.
The unfavorable situation of large carnivores is primarily a combination of two factors: carnivore range and human development. Carnivores naturally occur at lower densities than other animals because they cannot rely on easily available food like grasses. To acquire enough food, carnivores need to have big hunting ranges of sometimes several thousand square miles. This habitat requirement renders them vulnerable to human development such as roads or extractive industries in remote areas. Furthermore, in many regions humans do not accept large carnivores close to their homes because they perceive them as a risk to their livestock or their personal lives and culture. At the same time, large carnivores include some of the world’s most charismatic animals, admired by people for their beauty and strength.
To achieve more clarity around carnivores and to inform effective conservation strategies, an international team of researchers compiled results from field research and other leading scientific findings to analyze the effects of large carnivores on regional ecosystems and the planet at large. Their synthesis, recently published inScience, paints a new picture of ecosystem functioning and shows that carnivore conservation may be instrumental to the overall balance of the environment. The extirpation of wolves in Yellowstone National Park, for instance, led to a decline in hardwoods in riparian areas as a result of increased browsing by herbivorous elk, their main prey. Without wolves, the elk felt safe in the open areas close to streams; they increased feeding on the fresh green of young aspen and willows. The reduced tree vegetation on the stream bank led to more erosion and poorer water quality. After the return of wolves to Yellowstone in the mid 1990s, researchers observed a significant recovery of hardwoods in some areas, and advantages for other species such as beavers.
Carnivores can also contribute to climate change mitigation by increasing carbon storage in plants. In Alaska, sea otters have declined since the 1970s; their preferred prey, sea urchins, graze on kelp, an underwater plant. Without sea otter predation, the sea urchins flourished and greatly reduced underwater kelp forests. The negative effect on carbon storage by kelp was so big that its value corresponds to approximately $200-400 million on the European carbon market. These examples showcase the often unexpected, far-reaching, and positive influences carnivores have on the ecosystems they live in.
To exert their functions in ecosystems, the scientists argue, carnivores need to occur in sufficient numbers. A main challenge is to overcome an outdated conception of what carnivores are—and what they aren’t—as well as how they live. Tourism may be one option for increasing the value of carnivores for local communities. In Yellowstone, wolves contribute tens of millions of dollars annually to the region by attracting tourists from afar. A possible benefit of carnivores for livestock herding communities could be the reduction of disease spillovers from wild herbivores to domestic cattle. Understanding the interactions between human land use and the complex relationships between carnivores and their environments is a necessary step toward finding conservation approaches that serve the needs of all stakeholders.
Conservation strategies need to account for the multi-facetted way in which carnivores interact with their human and natural surrounding. Building on the model of the Large Carnivore Initiative for Europe (LCIE), the researchers recommend the establishment of a Global Large Carnivore Initiative, responsible for creating and distributing knowledge and informing policy decisions. They propose a two-pronged approach to conserving large carnivores, recognizing (a) their ecosystem effects and their related social and economic benefits, and (b) the intrinsic value of a fully functional ecosystem and the associated moral obligation humanity has to allow for dynamic ecosystem processes.
Carnivores can assist forest growth by regulating herbivores, they can foster carbon storage, and they can cause conflict with some local people while making money for others. To ensure the survival of some of our world’s most iconic species and to continue reaping the benefits of healthy large carnivore populations, it is time to go beyond prejudice and to build bridges between the diverging attitudes of actors surrounding large carnivore management.