Humpbacks Keep Saving Other Animals From Killer Whales. Scientists Think They Know Why / Guardians

In Monterey Bay, five killer whales are closing in on a gray whale mother and her month-old calf. Then two humpback whales, more than a kilometre away, turn around and swim straight into the fight. They are not related. They are not even the same species. Why would a whale that eats krill take on the ocean's top predator for a stranger? Follow the guardians of the sea, from a seal lifted onto a humpback's chest in Antarctica to the scars that may explain it all. This story is based on real research. In 2009, off the Antarctic Peninsula, Robert Pitman watched a Weddell seal escape wave-washing killer whales by climbing onto the chest of a humpback that rolled onto its back and nudged the seal back up with its flipper. Pitman and colleagues later compiled 115 interactions between humpbacks and killer whales: humpbacks usually approached, mobbing was aimed almost entirely at mammal-eating killer whales, and in 89 percent of cases with identified prey the victim was another species, from seals and sea lions to gray whale calves and an ocean sunfish (Pitman et al., Marine Mammal Science, 2016). Mammal-eating killer whales hunt silently and call after an attack (Deecke, Ford & Slater, Animal Behaviour, 2005). Killer whale tooth-rake scars on humpback flukes are acquired mostly as calves (Mehta et al., 2007; Steiger et al., 2008). In May 2012, observers in Monterey Bay watched humpbacks stay for hours beside a gray whale calf taken by killer whales. Grace and the two humpbacks in this film are illustrative characters built from these records. 0:00 The hunt 0:56 The big wings 2:25 A seal on a whale 3:18 One hundred and fifteen times 4:23 They choose their enemy 5:01 Why? 6:21 Back in the bay 7:41 The guardians 8:14 A simple rule #humpbackwhale #killerwhale #wildlife