An orca throws up its fluke while trying to avoid an angry humpback whale. Photo: Courtesy of ©Alisa Schulman-Janiger

Transient killer whales are generally afforded a wide berth during feeding events, which are spectacularly brutal when they involve separating a gray whale mother and calf.

But on Monday in Monterey Bay, after a pod of killer whales had logged its sixth calf kill in 12 days, several nearby humpback whales lashed out in apparent rage.

The accompanying rare footage, captured via drone by Monterey Bay Whale Watch, shows the humpback whales trumpeting angrily  and swiping at the orcas with powerful tail thrusts, seemingly to prevent them from reaching the submerged calf carcass.

This was one of several remarkable encounters logged by boaters recently in Monterey Bay. On Sunday, whale watchers watched in awe as a mother gray whale successfully defended her calf against the same killer whales.

On Monday, the calf had already been killed when the Monterey Bay Whale Watch vessel arrived. The mother had fled and the humpbacks appeared to be trying to protect the calf from the black-and-white predators.

Humpback whale (left) spyhops while trying to prevent an orca from reaching a gray whale calf carcass. Photo: Courtesy of ©Alisa Schulman-Janiger

Alisa Schulman-Janiger, a killer whale researcher who was present, along with fellow researcher and captain Nancy Black, said such behavior by so many humpback whales is rare, and to capture it on video is even more unusual.

"Humpbacks are coming in more often to kills," she told GrindTV. "But usually as a pair, with a bit of trumpeting and a few tail slashes. This time there were multiple groups of humpbacks: five whales abreast at one point."

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The killer whales were obviously distracted, but easily managed to stay clear of the larger whales as they circled the calf, which they eventually consumed.

Transient killer whales prey almost exclusively on other marine mammals. Each spring they gather in Monterey Bay and use its deep canyons to ambush migrating gray whale cow-calf pairs. The fatty calves provide more sustenance than smaller prey such as dolphins and sea lions.

Thankfully for gray whales, many seasoned mothers know to stick close to the coast in this area and usually advance safely through the gauntlet.

Adult male gray whales do not accompany cow-calf pairs during the migration from Mexico’s breeding and nursing grounds to Arctic feeding grounds.