Feb 1, 2018

The boom-or-bust life of an Arctic polar bear

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.

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World coronavirus updates: Confirmed cases top 1.2 million

Data: The Center for Systems Science and Engineering at Johns Hopkins, the CDC and China's Health Ministry. Note: China numbers are for the mainland only and U.S. numbers include repatriated citizens and confirmed plus presumptive cases from the CDC

The number of novel coronavirus cases surpassed 1.2 million worldwide Saturday night, as Spain overtook Italy as the country with the most infections outside the U.S.

The big picture: About half the planet's population is now on lockdown and the global death toll was nearing 64,800, by Sunday morning, per Johns Hopkins data.

Go deeperArrowUpdated 3 hours ago - Health

U.S. coronavirus updates: Death toll surpasses 8,500

Data: The Center for Systems Science and Engineering at Johns Hopkins; Map: Andrew Witherspoon/Axios

Recorded deaths from the novel coronavirus surpassed 8,500 in the U.S. early Sunday, per Johns Hopkins data. The death toll in the U.S. has risen over 1,000 every day for the past four days, since April 1.

The big picture: President Trump said Saturday America's is facing its "toughest" time "between this week and next week." Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, said U.S. deaths are expected to continue to rise during this period.

Go deeperArrowUpdated 4 hours ago - Health