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Cameras mounted on polar bears have captured the fine line between feast and famine that characterizes bear life. In a study published Thursday in the journal Science, researchers found that polar bears burn more calories while hunting than previously believed.

Why it matters: Some populations of bears — including these bears on the Beaufort Sea — are in decline. As the Arctic warms and sea ice melts, bears will have to travel farther each hunting season. This study provides a baseline that will help researchers understand the impacts of climate change on polar bears in the future.

What they found: Polar bears are ambush predators. They hide near holes in the ice, waiting for seals to come up for a breath. Then, they pounce. Researchers had previously thought this method helped bears save energy, but this study shows that may not be the case. In an 11-day period, an unsuccessful bear could lose up to 10% of its body mass, while a successful bear could gain the same amount.

“We certainly didn’t expect to see such dramatic changes in body mass over such a short period of time,” study author and U.S. Geological Survey biologist Anthony Pagano tells Axios.

What they did: Researchers placed GPS collars, cameras, and metabolic trackers on 9 different female polar bears. A few bears were tracked each year, from 2014-2016. The cameras and collars stayed on the bears for an average of 11 days.

Why they did it: There are few studies of bears in their natural habitat. Seminal research was conducted by Ian Sterling decades ago, while he sat on a cliff and watched bears hunt. That, says Pagano, is the foundation that much polar bear behavioral research is based on. The bears that roam the sea ice of the Beaufort Sea are more mysterious. They’re difficult for scientists to study or follow. Since different populations of bears are responding differently to climate change, it’s important to know how their behaviors and metabolic needs vary across regions.

Go deeper

"Atmospheric river" to whiplash Northern California from drought to flood

A map depicting 24-hour preciptation forecast (inches) ending Monday at 5a.m. local time. Photo: NOAA

A series of powerful "atmospheric river" storms are set dump historic amounts of rainfall across parts of drought-stricken California and the Pacific Northwest from this weekend, forecasters warn.

Why it matters: A strong atmospheric river, packing large amounts of moisture, is predicted to whiplash Northern California from drought to flood.

10,000 trees near giant sequoia groves to be removed after fires

A firefighter looks up at a giant sequoia tree after fire burned through the Sequoia National Forest near California Hot Springs, California, on Sept. 23. Photo: Patrick T. Fallon/AFP via Getty Images

"Upwards of" 10,000 trees near giant sequoia groves have been "weakened by drought, disease, age, and/or fire" and must be removed in the wake of California's wildfires, the Sequoia and Kings Canyon National Parks announced.

Why it matters: The damage to these trees, considered "national treasures," and work to remove them means a nearby key highway must remain closed to visitors as they have "the potential to strike people, cars, other structures, or create barriers to emergency response services," per a statement from the national parks.

Obama stumps for McAuliffe, urges Virginians not "to go back to the chaos"

Photo: Win McNamee/Getty Images

Former President Barack Obama framed a Nov. 2 gubernatorial race as a bellwether for the Democratic Party and the country, telling a crowd at a campaign event for Terry McAuliffe on Saturday that "I believe you, right here in Virginia, are going to show the rest of the country and the world that we're not going to indulge in our worst instincts."

Why it matters: With just over a week to go before Election Day in the Commonwealth, McAuliffe is bringing out the big guns. The 44th president appeared on the campus of Virginia Commonwealth University to urge supporters to get to the polls.

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