This year, migrating humpback whales came to Monterey Bay, California, earlier than usual, and they weren’t happy to find they were sharing the bay with a pod of orcas. The early arrival of these humpback whales–numbering around 60 to70 so far–overlaps the humpbacks with the orcas' hunting season. This is typically the season when orcas hunt smaller grey whale calves. So far, the humpback whales are none-too-happy to be sharing the bay, and have been actively interfering with orca hunts, driving them away from both potential prey and fresh kills.
This overlap coincides with the largest collection of orcas and grey whales known to converge in the region. These orcas have been on a bit of a feeding frenzy of late, killing an unprecedented number of grey whale calves. Nancy Black, a marine biologist and co-owner of Monterey Bay Whale Watch said, “The first attack was pretty spectacular because there were 33 killer whales involved in that, which is an extraordinary number.” Orcas usually hunt in packs numbering a half-dozen to a dozen while hunting grey whales, moving in and out of Monterey Bay. However, this year the orcas seem to have parked themselves in the bay and have killed seven whales over the past two weeks.
The arrival of 60-70 humpback whales has put a damper on the orcas' grey whale feast. The humpbacks have been aggressively chasing off any orcas they see feeding or hunting. As Black told the San Francisco Chronicle, "Humpbacks like to interfere with the killer whales for some strange reason, they seem to want to protect the prey."
Scientists say that it is quite common for humpback whales to interfere with orcas and protect other groups of prey besides their own. However, marine biologists note that the aggressiveness shown by these humpbacks is probably not altruistic. Orcas are one of the few predators that threaten humpback calves. The humpbacks' reaction to orcas, even when hunting other food sources, may just be one of instinct.
Whatever the reason, the humpback whales have been giving the orcas of Monterey Bay a run for their money over the past couple of weeks. They have been seen repeatedly and aggressively interrupting orcas both during hunts and while feeding. Working together, groups of humpbacks have been seen swimming in to intercept and chase off orcas, trumpeting loudly to scare them off. They have also been seen, as you can see in this video, attempting to push orcas off feeding sites using their flukes.
So far it seems that the humpback whales have not prevented the orcas from killing their prey, but it hasn’t been for a lack of trying. One grey whale calf was saved by her mother this past week, when she took a deep breath, lifted her calf up on her back out of the water, and swam her for seven straight minutes to the beach. You can see that amazing feat here, courtesy of KSBW 8 News.
Nancy Black noted to the Chronicle that these sort of interactions are so rare in Monterey Bay, that in her 30 years as a marine biologist in the area, she has never seen anything like it. As grey whales usually migrate through the area throughout April and May, this epic whale war is likely to continue to wage for the next several weeks, making it a great time to go whale watching.