Category: Science Magazines

Pumas feel the fear near humans

Justine’s recent paper in the Proceedings of Royal Society B received quite a bit of attention from the press.  Reports about it appeared in Science, Nature, BBC and the Naked Scientists among others.  Here’s snippet from Nature

Female pumas that live near human populations hunt more often but spend less time eating their prey than do those in less populated areas.

Humans can cause declines in wildlife populations, but their effect on animal behaviour is less well understood. Justine Smith and her colleagues at the University of California, Santa Cruz, tagged 30 pumas (Puma concolor) in California and tracked their movements in areas with four different densities of human housing. They found that at kill sites near the most densely populated areas, female pumas spent 42% less time consuming their prey than those in the least populated regions. To compensate, the females in the more developed habitats killed 36% more deer.

Fear of humans is probably driving this behavioural change, which could have further ecosystem effects, such as boosting scavenger populations and even compromising the reproductive health of female pumas, the authors speculate.

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Wild cats need to count calories, too

Science coverage or our – wait for it – article in Science.  With all the “coverage”, does any read the original article?

A sleek cheetah races with legs outstretched, leaping with a great burst of energy to bring down a fast-moving antelope. That iconic image of this African wild cat needs a footnote. The world’s fastest runner actually spends very little time and energy at full speed, a new study finds. Instead, its most strenuous activity is simply walking around in the hot sun, looking for potential prey. It’s much the same story for the cheetah’s American cousin, the puma, which spends more than twice as much energy locating prey than researchers had predicted.

Read the full coverage here and here.

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Cheetahs and pumas may have hunting strategies down to a science

Another nice article on our recent Science paper.  This one in the LA Times.

It’s not easy being a lean, mean killing machine. Whether a fleet-footed cheetah or a lie-in-wait puma, a hunting feline’s survival balances on the point between how much energy they lose in hunting for a meal and the energy they gain from actually eating it. Now, two new studies in the journal Science follow these big cats to find out how they make this lifestyle work.

Read the full article here.

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Declining fortunes of Yellowstone’s migratory elk

This press release from Ecology nicely summarizes our recent Ecology paper in a forum discussing the fate of Yellowstone’s migratory elk.

“I think Middleton has an intriguing idea, and it might be what’s happening. We offer another hypothesis that also fits the data that they have. He says it’s climate change on the summer range and more predators on the summer range. I think it’s because there is irrigation that provides the sedentary elk with food. And I think it’s also that there is predator control outside the park,” said Wilmers.

While wolves and grizzlies have been thriving inside the park, predator control measures have intensified outside the park, Wilmers said. “My hypothesis is that in that crucial winter period, the migrants are coming down to range that the resident elk have already been feeding on all summer, and now they are competing for in the winter,” he said. To distinguish between these two stories would require hypothesis testing, he said – pitting them against each other and testing them with more data.

Read the entire press release here.

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Could an Alaska mining project jeopardize Earth’s largest bald eagle gathering?

High Country News article about our lab’s work in Alaska.

… By late morning, eagles are all around us. “Look at that eagle party across the way,” says Taal Levi, a wildlife ecologist with the Cary Institute of Ecosystem Studies, whose tales of this ecological mother lode inspired Wheat’s doctoral project. He points to 50-plus eagles bunched in cottonwoods beyond the river, explaining that since they’re not breeding, they’re less territorial. “Though they do like to steal from each other.”

As if on cue, an adult chases a young bird from some bait near a remote-controlled net gun, and bingo — Lewis flips the switch. Like a starter’s pistol at a track meet, the gun’s crack sends us dashing toward our catch.

Lewis carefully extracts feathers from the netting. He pops a hood over the giant raptor’s head, covers its shiny black talons with handmade leather booties, then hands the bird to Wheat, who cradles it against her chest as she heads back to the road.

At almost 15 pounds, it’s clear we’ve got a female. She’s fearsome, with a massive hooked beak and flesh-shredding talons that curl around Lewis’ exposed fingertips after he takes off a bootie to give us a peek. Yet she sits calmly as Lewis threads a Teflon harness with the GPS under her wings and around her chest, positioning the device just behind her head. Her breast feathers feel silky and warm against the frosty air.

Wheat clips a few of them for stable isotope analysis, which ecologists have long used to infer an animal’s diet based on the levels of carbon and nitrogen. Wherever birds forage, the elements in the food suffuse their feathers as they grow. Wheat hopes the approach, tested in songbirds but not eagles, will tell her where the migrants lived and fed before she tagged them.

Read the whole article here.

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Top Cats: How Pumas and Other Apex Predators’ Populations Affect The Big Biodiversity Picture

Here’s a great article by Liza Gross in KQED’s Quest.  It ties our recent puma work nicely together with other work on predator effects on ecosystem function.

These “top down” trophic cascades, which the ecologists dubbed “trophic downgrading,” have been documented from the poles to the equators and every major biome in between, making the loss of top predators, they wrote, “arguably humankind’s most pervasive influence on the natural world.” Earth has weathered five mass extinctions but never before at the hands of one species—human beings. And we humans seem hell bent on clearing the Earth of larger bodied apex predators.

I considered all this as I read a new paper from wildlife ecologist Chris Wilmer’s lab (published last week in PLOS ONE) that looks at how human development affects pumas. Like most large carnivores, pumas need vast territories to hunt, find mates and raise young. Pumas living in the San Francisco Bay Area have no such luck. Wilmers, an associate professor of environmental studies at the University of California-Santa Cruz, has been studying the effects of habitat fragmentation on the behavior, ecology and even the physiology of pumas around the Santa Cruz Mountains. He develops cutting-edge GPS collars to track both the location and behavior of his animals.

Fragmented landscapes often pave the way to extinction for wide-ranging large carnivores like pumas, with cascading effects. Freed from the threat of top predators, smaller carnivores like foxes increase in number, driving declines in birds and small mammals. But habitat fragmentation can produce effects similar to extinction because large predators tend to avoid small fragmented parcels. Given the heterogeneous patterns of human developments—with houses and other structures interspersed among natural areas—predicting how animals might respond, and with what consequences, presents a serious challenge.

Read the full article here.

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The Rise of the Tick

Outside Magazine has a nice story on Lyme disease ecology in which they discuss some of the results of our recent PNAS paper.

Some species may even be able to control tick numbers and infection prevalence not by killing the ticks but by killing their favorite hosts. That is the new argument that Taal Levi, a postdoctoral researcher at the Cary Institute, put forward in a 2012 paper in the Proceedings of the National Academy of Sciences. After the morning tick drag, I sat down with Levi at a picnic table outside the institute to hear about the history of foxes.

Foxes were originally very abundant in the eastern United States, where they feasted on small mammals like white-footed mice. But the past few decades have not been good to them. “Fox harvests in the Northeast have declined substantially,” says Levi.

Taal is continuing this work in his postdoc at the Cary Institute in New York.  Read the whole story here.

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Fear and Loathing in Wolf Country

Here’s a great all around article about wolves by Liza Gross, just appearing in QUEST, which draws on some of our research in Yellowstone and Alaska.

Though Ecology 101 tells us that healthy ecosystems need top predators, researchers are just beginning to understand how the presence—and absence—of wolves affects other species.One study found that wolves may buffer the effects of climate change in Yellowstone National Park, where winters have been getting shorter, by leaving their moose and elk leftovers for eagles, ravens, coyotes and other scavengers. Another papersuggests that the absence of wolves may explain the precarious status of the Canada lynx. No wolves means more coyotes—which hunt snowshoe hares, the lynx’s favorite food—and more elk and deer—which eat the shrubby vegetation that sustain and shelter hares. And a 2011 paper in Biological Conservation supports earlier work showing that wolves in Yellowstone influence the behavior of deer and elk, releasing grazing pressure on vegetation, which in turn increases songbird habitat and diversity.

Read the full article here.

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More coastal salmon spawning helps grizzlies and fisheries

From Conservation Magazine, a short article on our recent PLoS Biology article:

Letting more salmon escape fisheries along the coast could boost both grizzly bear populations and fishery yields, according to a new study in PLoS Biology.

Fishery managers already let a certain number of salmon slip away so those fish can spawn. But it’s not clear which “escapement” level is best for the fisheries and the ecosystem. Grizzly bears eat salmon and often leave the remains of their meals by streams, providing nutrients for plants and animals. And the number of spawning fish also affects fishery yields down the line.

Researchers tackled the problem by modelling the effects of different escapement levels for four coastal sockeye salmon stocks and two inland stocks in Alaska and British Columbia, Canada. In the coastal systems, leaving more salmon to spawn would increase bear density by 8 to 44 percent. Fishery yields would jump as well — “an apparent win-win situation,” the authors write.

Read the full article here.

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Let Them Run

From Conservation Magazine, a nice little article on our recent paper in Conservation Letters calling for a small number of fully protected salmon runs.

Ask not what a park can do for spawning salmon. Ask what robust salmon runs could do for the park – and for coastal fishing communities.

That’s the provocative idea behind a “radical” proposal being floated by a group of conservation biologists. Limiting fishing for some pink and chum salmon bound for spawning streams in British Columbia parks could reinvigorate ecosystems that thrive on the annual infusion of millions of fish carcasses. And, in the long run, protecting the runs could produce economic benefits by making ecosystems more productive and resilient to change.

“Although managers safeguard protected areas for migratory species, little consideration has been given to how migratory species might benefit parks,” a team led by Chris Darimont of the University of California, Santa Cruz, and the Raincoast Conservation Foundation in Canada write in Conservation Letters. Case in point: Headwaters streams in coastal parks in British Columbia once saw huge annual runs of Pacific salmon. Many of the spawned-out fish died, producing a “fertilizer effect” that pumped a vast pulse of nutrients into surrounding ecosystems. “The breakdown of salmon carcasses…  ultimately can affect communities of riparian plants, terrestrial and freshwater invertebrates, resident fish, and songbirds,” the authors note. These days, however, commercial and recreational fishers kill up to 90% of the fish before they can spawn, blocking the transfer of nutrients.

To restore at least part of that pulse, the authors propose limiting catches of pink and chum salmon(Oncorhynchus gorbuscha and keta), which have still have large runs but low commercial value. While Chinook salmon sold for $1.23 a pound in 2002, for instance, pink and chum sold for just 6 to 16 cents a pound. “We believe that a focus on pink and chum… provides opportunity to implement our ideas without severe economic consequences.”

The authors concede that “some might deem our idea politically unachievable,” but add that their “aim is to inform and inspire decision-makers with a plan that not only favors biodiversity but also one that ultimately might yield economic and management benefits. Our goal is to inoculate the literature with a provocative idea to stimulate discussion.”

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