Killer whale moms are still supporting their adult sons — and it's costing them

A new study finds that orca mothers still feed their adult sons. It's a bond that may come with costs, researchers say. (David K. Ellifrit/Center for Whale Research / NMFS research permit #21238)

Twenty years ago, in the waters off the coast of Washington State and British Columbia, an adult female killer whale (dubbed K16 by those who know her well) gave birth to a son, K35.

"These two have an extremely close social relationship," says Michael Weiss, the research director at the Center for Whale Research in Friday Harbor, Washington.