Carnivores play an important role in our worldwide ecosystems and, according to a paper released today from a team of scientists, a world without these species is scarier than a world with them.
From sea otters that keep sea urchins in check and enable the rise of kelp beds thus increasing the productivity in inland coastal areas, to pumas that mediate the browsing of mule deer and thus enhance the growth and reproduction of woody plants, the scientists profiled seven of the 31 largest species of the order Carnivora and their well-studied ecological effects.
The paper, “Status and Ecological Effects of the World’s Largest Carnivores,” appears in the Jan. 10 issue of the journal, “Science.” More than 100 published studies were reviewed to offer a comprehensive look at the state of carnivores and their impacts on the world today, a release from the Wildlife Conservation Society said.
Among their many impacts, carnivores are a benefit to ecotourism. Yellowstone National Park’s restored wolf population, for example, brings in tens of millions of dollars in tourist revenue each year. And when wolves are absent, the effect on natural selection is dramatic.
“In Badlands National Park, we have observed bison born with deformed hooves or portions of their legs missing,” Joel Berger said.
Berger is a WCS Conservation Scientist and author of “The Better to Eat You With.”
“Historically, these bison would have been selected out for predation by wolves, contributing to the overall health of the herd,” he said. “Today, without wolves, these bison survive and reproduce. This is not the way healthy ecosystems are maintained.”
The ecological services provided by carnivores are multifarious. Carnivores control herbivores to the relief of plants, mitigate global warming, enhance biodiversity, restore rivers and streams, and regulate wildlife disease and livestock disease spillover.
However, many of the largest carnivores are listed as threatened on the International Union for the Conservation of Nature Red List, and most are still declining in numbers. These “top” or “apex predators” have one great competitor: humans.
The authors note that “large-carnivore population declines are typically precipitated by multiple, and sometimes concurrent, human threats including habitat loss and degradation, persecution, utilization (such as for traditional medicine, trophy hunting or furs) and depletion of prey.”
Oregon State University professor and lead author of the paper, William J. Ripple said the issue is one that is worldwide in reach.
“Globally, the ranges of carnivores are collapsing and many of these species are at risk of either local or complete extinction,” he said. “It is ironic that large carnivores are disappearing just as we are learning about their important ecological and economic effects.”
Looking to the future, the scientists said they expect that the loss of apex predators will bring degradation to ecosystems that include reductions in plant diversity, biomass and productivity as well as wide-ranging impacts to other species. Greater rates of herbivory and concurrent decline of plant species may hasten global warming and desertification.
Critical to living with carnivores, the scientists conclude, is an understanding of the benefits they provide and where human/predator conflicts arise. Linking policy issues facing people such as population growth, meat consumption and exploitation of wild prey, livestock production, greenhouse gas emissions, food security, deforestation and desertification, and water quality/quantity with carnivore conservation is a necessary step toward coexistence.
Authors of the study include: William J. Ripple, Robert L. Beschta, and Michael P. Nelson of Oregon State University; James A. Estes and Christopher C. Wilmers of the University of California, Santa Cruz; Euan G. Ritchie of Deakin University (Victoria Australia); Mark Hebblewhite of the University of Montana, Missoula, and Fondazione Edmund Mach (Italy); Joel Berger of the University of Montana, Missoula, and the Wildlife Conservation Society; Bodil Elmhagen of the University of Stockholm (Sweden); Mike Letnic of the University of New South Wales (New South Wales, Australia); Oswald J. Schmitz of Yale University; Douglas W. Smith of the Yellowstone Center for Resources, Yellowstone National Park; Arian D. Wallach of James Cook University (Queensland, Australia); and Aaron J. Wirsing of the University of Washington, Seattle.
For more on the Wildlife Conservation Society, check out the website at http://www.wcs.org.