Category: National Geographic

Pumas Trained to Run on Treadmill Help Explain Big Cat’s Ambush Strategy

A nice article in National Geographic on our recent Science paper on puma energetics.

The group, led by Terrie Williams and Chris Wilmers of the University of California, Santa Cruz, spent years working with engineers to develop a novel wildlife tracking collar to measure the energetics, movements and behaviors of animals in the wild. Energetic expenditure is the lifeblood of an animal, says Wilmers. “If they’re burning more calories than they’re consuming they’ll die. And without enough surplus calories, they’ll never reproduce successfully.”

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Sea Otters Strike a Blow for the Environment?

From National Geographic, a short well-done article on our recent sea otter – carbon pub.

When hungry sea otters whack spiky urchins against rocks on their chests, the mammals may also be striking a blow against global warming.

By preying on urchins—which themselves devour greenhouse gas-absorbing kelp forests—the sea otters encourage the plants to flourish.

The result? An otter-assisted kelp forest “can absorb as much as 12 times the amount of CO2 [carbon dioxide] from the atmosphere than if it were subject to ravenous sea urchins,” according to the study, published Friday in the journal Frontiers of Ecology and the Environment.

Based on a new analysis of 40 years of data on both otters and Pacific kelp forests off Alaska and Canada, the study concludes that “otters ‘undoubtedly have a strong influence’ on the cycle of CO2 storage,” if only in their local environments.

So are sea otters the new global warming “warriors,” as some headlines have it?

Not exactly, said Jeffrey Dukes of the Purdue Climate Change Research Center in Indiana.

The otter-induced increase in CO2 absorption is “relatively inconsequential in terms of the big picture of climate change,” said Dukes, who wasn’t part of the study. But, he added, it’s “an interesting study identifying how dramatically a predator can alter the cycling of carbon in an ecosystem.”

Study co-author Chris Wilmers, a biologist at the University of California, Santa Cruz, agreed that the offset is “unlikely to have a big effect on global warming” worldwide.

But while otters alone can’t do the job, such seemingly incremental, natural advantages may become ever more important as we look for ways to blunt climate change’s impacts, according to study co-author James Estes, also of UC Santa Cruz.

“The general phenom in which the interactions between species are linked to the carbon cycle,” he said, “is going to be very important.”

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Wolves’ Leftovers Are Yellowstone’s Gain

From National Geographic, a nice article about our recent work on the effects of gray wolves on scavengers in Yellowstone NP.

Amid controversy, gray wolves (Canis lupus) were reintroduced to Yellowstone National Park in 1995. Now, new studies are hinting at the added benefits that the once-spurned carnivore have rapidly brought to the preserve.

Research published last month revealed that—unlike other top predators—Yellowstone’s wolves routinely leave unfinished elk (Cervas elephas) and moose (Alces alces) carcasses. These provide essential scraps for scavenging coyotes (Canis latrans), eagles, and other animals. Related work suggests that these carcasses provide dinner more consistently, and for more species, than remains discarded by human hunters.

Other recently published findings show that wolves may also be rebalancing Yellowstone’s ecosystems. Some streamside trees, such as species of cottonwood (Populus) and willow (Salix) are growing vigorously once more in areas overgrazed for much of the last century, researchers wrote.

“Part of the integrity of the ecosystem has been restored,” said Christopher Wilmers, an ecologist of the University of California, Berkeley, and lead author of two of the studies. The findings vindicate the decision to bring wolves back, he said.

Wiped Out

Wolves were systematically hunted in Yellowstone and much of the Western United States from the 1800s onwards. Yellowstone’s last pack was eliminated in 1926.

“In the early 1900s no one stopped to consider the ecological role of wolves,” commented Robert Beschta, a forestry scientist at Oregon State University in Corvallis. “Wolves were considered a predator with no value and seen as a huge constraint on allowing a productive ecosystem to flourish,” he said. Wolves, mountain lions (Puma concolor), and coyotes (Canis latrans) were all targeted as threats to livestock and game, he said.

When the National Park Service first considered reintroducing wolves in the late 1980s, critics warned that the predators might seriously impact elk, deer, and moose herds. Nevertheless, 31 wolves were re-introduced in 1995 and 1996 to Yellowstone, which spans portions of Idaho, Montana, and Wyoming. That population, now living in the vast park and its surroundings, had swelled to 220 animals in 21 packs by the end of 2001.

While elk numbers have been reduced by around 18 percent since the mid-1990s, few devastating impacts associated with the reintroduction program have yet been recorded, said Wilmers.

Feeding the Masses

Instead, the park is now enjoying some wolf-related benefits. According to Wilmers and colleagues’ study, published in the November Journal of Animal Ecology,wolves may be providing other scavengers with more regular meals than they’ve had since the early 20th century.

Mountain lions and grizzly bears (Ursus arctos) have a habit of sticking close by their kills, even when full. Wolves, on the other hand, tend to move away to “sleep off their meal,” said Wilmers, making meat available for scavengers.

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Alaska Bay Area British Columbia carbon cascade climate change collars connectivity corridor elk energetics evolution fear fish habitat fragmentation Lyme disease overexploitation predator puma salmon scavenger sea otter treadmill wolf Yellowstone