Erin Ross Feb 1
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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.

What's next for cancer immunotherapies

A researcher holds a plate used to grow T cells.
Photo: BSIP/UIG via Getty Images

Cancer immunotherapies that trigger a person's own immune system to recognize and attack cancer cells have logged some success in certain patients and with certain types of cancers. "But overall that is a minority of cancer patients," says Antoni Ribas from the University of California, Los Angeles.

Now, researchers are looking to leverage their understanding of what's working and what's not in patients receiving this class of drugs. (Science published a special section about cancer immunotherapy Thursday.)

The challenge: These are new avenues for research but they also spur serious concerns that must be addressed: unwanted and sometimes deadly side effects, unexplained lack of response by some cancers, and questions arising from combining multiple therapies and finding the optimal timing — which can make or break treatment.

The worst flu season in eight years

Note: Activity levels are based on outpatient visits in a state compared to the average number of visits that occur during weeks with little or no flu virus circulation; Data: Centers for Disease Control and Prevention; Chart: Chris Canipe/Axios

This year's flu season caught many experts off guard with both its sustained prevalence and its virulence. At its peak, there was a higher level of flu-like illnesses reported than any other year during the past eight years. Watch in the visual as it hits its peak around Week 18.

Why it matters: Public health officials try to capture this data when developing the next year's vaccines. And, of course, they want to find better ways to prevent severe flu seasons. There's a "Strategic Plan" to develop a universal vaccine to protect against a wider range of influenza viruses, Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, tells Axios.