Updated on April 28, 2017
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Updated on April 28, 2017
In some circles April 20, notated as 420, is a date to toke up, get stoned and celebrate cannabis. This year on the University of California Santa Cruz campus overlooking Monterey Bay, 3000 revelers did just that.
But in other circles, the date is synonymous with killer whales. 4/20 is historically the date on which mammal-eating transient killer whales have been most consistently sighted in Monterey Bay. And they did not disappoint once again this year!
From 2009 to the present they’ve been seen on April 20 in all years but one, with bad weather keeping boats off the water on the odd year. The two years previous, the orcas were here a day or two later. Last year on April 20th, I captured photos of killer whales conducting a training session for their young on how to properly conduct a hunt of a hapless and doomed California sea lion. The day before, I photographed a different family group, which successfully killed a Northern elephant seal, and on the 23rd I documented a couple of other family groups taking down a gray whale calf.
I got lucky again this year, after following advice about the auspicious date from killer whale researcher and ACS/LA Gray Whale Census Director, Alisa Schulman-Janiger. I joined her on the Pt. Sur Clipper, part of the Monterey Bay Whale Watch fleet, owned by 30-year killer whale researcher and marine biologist with the California Killer Whale Project, Nancy Black. Black was our skipper as we headed out to the whales, following a report of “lots and lots of killer whales in the Bay.” Upon arrival, judging from their behavior, Black was certain they had taken a gray whale calf, either earlier that morning or sometime during the night. Thirty-plus mammal-eating transient killer whales were spread out as far as the eye could see.
We quickly settled in with a large and active group, which Black told her passengers were feeding on the calf carcass below. The carcass was not actually observed until the next day, when the whales, still hard at work feasting on the blubber, raised the remains to the surface. But Black knew that first afternoon that a kill had occurred based on her extensive experience and the behavior we witnessed. The dozen or more whales we watched circled and dove in the same general vicinity for the three hours we were present. They also treated us to celebratory breaches and tail throws, a common sight after a successful hunt.
According to Black, “There was a slick that had started to form, and scattered sub-groups were milling in all directions within a ¼ mile, but staying in the same vicinity. A slick of oil always forms as the blubber is pulled apart. There is usually one main slab, but as the whales peel off all the blubber, there will be multiple chunks scattered about.”
One of those subgroups was orca Emma’s family of six, including her daughter Louise and her granddaughter Little B. In fact, the whale presumed to be Emma’s mother was also present, making four generations gathered for the feast. Emma is well known in these parts and has a reputation for being an active participant in many gray whale kills.
It is no surprise that mammal-eating transient killer whales would be seen in Monterey Bay during the month of April. This is the time of year gray whale mothers are migrating north from calving grounds off Baja California with their new calves. They are hoping to make it to their feeding grounds beyond Alaska. For most of their journey, the gray whales hug the shoreline on their way north, sticking to shallow waters where it is difficult for the killer whales to hunt. Monterey Bay with its deep submarine canyon is a favorite place for the orcas to stage an attack in order to feed their families on these calorie rich calves. And that afternoon we watched ten matrilineal families doing just that.
But do the killer whales have a calendar? How do they know April 20 is the day to hit the Bay? Many years they arrive earlier in April and hunt sea lions, elephant seals and dolphins if there are no gray whale calves in sight, and one could say they just ‘happen’ to be present on 4/20. But this year, the last significant sighting of transients in the Bay was April 2, with three whales making a cameo appearance on April 12.
Where do they hang out when not here? No one knows for sure, as there are only rare sightings of these mammal eaters in Southern California or sometimes as far north as British Columbia later in the year. According to Black, “April 20 appears to be a peak time for gray whales coming through. There must be a little swarm of gray whales coming through about this time.” But as for the specific date, Black says, “The 20th is a luck of the draw kind of day.”
According to Schulman-Janiger, this year, the gray whale northern migration is later than usual. Only 2-5 calves were seen passing Pt. Vicente, CA, where volunteers conduct the ACS/LA annual census count, in the days prior to our Monterey Bay ‘target’ date. It wasn’t until April 20th that as many as eleven calves were seen with a whopping fourteen the day after. But those whales were observed in southern California, a minimum five-day’s swim to Monterey Bay. However, the Piedras Blancas survey station, a two-day whale journey from the Bay, saw an increase from 14 calves passing by the week before, to 44 from April 18-21.
And how do so many killer whales know to show up for the feast? Since no one saw this gray whale calf kill, we do not know how many orcas were present for the hunt. Do they communicate and make a plan in advance? Do those not present for the kill hear the vocalizations and know it’s time to arrive? Some think yes.
According to a July 2016 paper by Robert L. Pitman with multiple co-authors including Black and Schulman-Janiger, “Unlike fish-eating killer whales, mammal eating killer whales in the North Pacific, and probably globally, are mostly silent when they hunt, presumably because their mammalian prey species all have acute hearing capabilities. Once they have detected potential prey, however, they often become vocally active, during and after attacks.”
The paper also notes, “The reason(s) for vocalizing in this context is not currently understood, but it could be important for coordinating attack behavior, or for calling in other killer whales—either to assist in the attack, to share in the kill, or for socializing.”
As we, and the whale watch passengers on our boat, watched and thrilled at the sight of killer whales, wild and free, going about the hard work of feeding themselves and family, two humpback whales arrived on the scene. They announced their approach by trumpeting loudly, a sign of agitation or aggression.
Black believes they were “attempting to interrupt the orca’s as they fed.” “They often try to prevent the orcas from either attacking prey or feeding,” says Black. In addition to their sonorous trumpet blows, the humpbacks rolled and slashed out with their flukes. At one point, a killer whale rapidly fled under our boat from the vicinity of the humpbacks.
Researchers ponder why humpbacks will attempt to prevent a kill of another species, or harass feeding mammal-eating killer whales at all. Some believe they may be engaging in altruism.
One of the two humpback whales that day wore orca rakes on its fluke, battle scars from an attack when it was a calf itself. Was this a revenge event, or just a way of showing off its strength as a warning? We’ll never know for sure. But we do know that lots of humpbacks engage in similar behavior, and not all sport scars from previous orca attacks. The Pitman paper reviewed 115 known and documented events.
Post Script: In the four days following April 20, two more gray whale calves became breakfast, lunch and dinner for the same killer whale families who made a successful kill on the ‘target date’. Emma was a key player in all those attacks. And on the 26th her clan was on its own taking down and feasting on a fourth calf. So far its been a tough season for gray whales, but clearly the orcas are on a roll and know something about timing we’re just beginning to understand.