Friday, January 10, 2014
Study Shows Large Carnivore Numbers and Range Declining Worldwide
New research co-written by University of Montana scientists finds steep declines in the worldwide populations and habitat range of 31 large carnivore species. The analysis, published Jan. 9 in Science, shows that 77 percent of the studied species – including tiger, lion, dingo and puma – are decreasing in number.
Associate Professor of ungulate habitat Mark Hebblewhite and John J. Craighead Chair and Professor of Wildlife Conservation Joel Berger, both of the UM College of Forestry and Conservation, co-wrote the study with scientists from Oregon State University, the University of California, Yellowstone National Park, University of Washington, Yale University and researchers in Australia, Italy and Sweden.
The study shows that 17 of the species occupy less than half their normal habitat range. These changes have serious environmental consequences, the authors argue.
Large carnivores are vulnerable to extinction because of their low population densities and their need to roam widely to search for food. These animals are essential to the health of an ecosystem and also provide social and economic benefits for humans.
“Ecosystems depend on large carnivores to control herbivores like deer and populations of smaller carnivores,” Hebblewhite said. “We suggest that losing a population of large carnivore doesn’t just impact that species, but an entire landscape.”
Further declines in the populations of these large carnivores will lead to changes in plant species diversity, biomass and productivity. These vegetation changes will have a wide-ranging influence on other species. Carnivore losses also will impact wildlife disease dynamics, wildfire and carbon sequestration.
Hebblewhite points to several success stories, like the reintroduction of gray wolves to Yellowstone National Park, potential delisting of grizzly bears in the Northern Rockies and the Global Tiger Initiative, to demonstrate that reintroducing and recovering carnivores has many benefits.
In Yellowstone National Park, the return of wolves has contributed to aspen and willow restoration, stabilized carrion availability for scavengers like grizzly bears and magpies, and has increased carbon storage by allowing plants to flourish.
But beyond the large carnivore conservation successes of the Northern Rockies, carnivore populations are declining worldwide, especially in Asia and Africa. These declines are mostly due to habitat loss, overhunting and trade of endangered wildlife parts.
“We haven’t yet untangled all the ways in which these large carnivore population declines will play out in the future – but we know they will have profound ecosystem impacts,” Berger said.
Hebblewhite and Berger agree that lessons learned from carnivore reintroduction in the Northern Rockies can serve as a model to the rest of the world. At UM, training international students in large carnivore conservation is a key focus.
Wildlife biology doctoral student Tshering Tempa currently applies some of these advances in carnivore science and conservation to Bengal tigers in his home country of Bhutan.
“Conservation has to be underpinned by sound science,” Tempa said. “In Bhutan, there is a real chance of ensuring that large carnivores and their prey persist perpetually. I am applying the skills I have learned at UM to contribute toward this.”
With looming threats to global distributions of large carnivores, Hebblewhite concludes that more science is needed to better understand all the benefits of every large carnivore species, which human activities are most in conflict with large carnivores, and what management activities will have the most impact on sustaining large carnivore populations.