One way to investigate the record-setting deaths of the marine mammals is to perform autopsies on them, but researchers are also taking a close look at living whales for clues to what could be killing them.
For the past two years, the charismatic marine mammals have washed up on Pacific shores in record numbers. Scientists investigating the strandings suspect warming waters and melting sea ice are partly to blame.
The release of gray wolves in Yellowstone decades ago still stands as one of the few examples of a predator reintroduction, and the lessons learned continue to be debated. New projects aim to do it again.