Orcas Prey On Migrating Grey Whale Calves

Saturday, April 24, 2004
CALIFORNIA - Killer whales in pursuit of prey have been thrilling local whale watchers over the past couple weeks.

Whale watchers have gotten their fix of killer whale sightings thanks to a bountiful grey whale birthing season. The transient killer whales, which prey on mammals such as grey whale calves, are particularly busy this time of year when the grey whales migrate up the California coast on their way to Alaska.

"It's that time of year when the grey whale mother calves are migrating north," said Nancy Black, a marine biologist with Monterey Bay Whale Watch. "There's a lot of killer whales who are feeding on the calves."

Since April 13, Black and her fellow whale watchers have seen almost a dozen of the 'transient' killer whales each day. Black said she has had the rare occurrence of witnessing several killer whale attacks on grey whale calves. She's seen as many as six attacks over the past week and a half.

"It's a natural thing, but this year it's been a really exceptional year where we have so many killer whale sightings every day," she said.

Steph Dutton, captain and co-owner of Sanctuary Cruises in Moss Landing, said the grey whales had a good birth season in the lagoons of Baja California in Mexico. That means more killer whale activity, but not necessarily more killer whales.

"It's not that there are masses of whales, it's that those who are here are working hard," he said. "They're here for a reason, and we're seeing a good number of attacks and a good deal of hunting."

Black attributed the grey whales' baby boom to a good feeding season, which allows the mothers to give better care to their offspring.

"Each year is different. It depends on the feeding season," she said. "If the mother whale has a good eating season, she can support her calves."

The flourish in activity has allowed marine biologists to monitor the killer whales' predatory behavior. The whales normally don't swim close to shore, but with the high number of calves, they are coming into shallow waters, Black said.

Despite the killer whales' fearsome name, they are not known to attack humans.

The activity should continue through late May, when the last of the female grey whales migrate north. That means whale watchers will get to see plenty of action between now and then.

"This is one of the best places in the world to see transient killer whales," she said. "It's still happening, and if the mothers and calves migrate through May, it could continue."