A method used by fuel companies to avoid polar bear dens before they search for oil or gas works less than half the time, according to a new study released Thursday. That failure could pose a grave risk to mothers and their cubs in the dens, which are hidden under ice, if the Trump administration finalizes its plan to expand drilling into the Arctic National Wildlife Refuge.

Berlin's latest zoo celebrity, a fluffy polar bear cub, made her first tentative steps on the public stage Friday, with media hungry to anoint her the rightful successor to late lamented superstar Knut.