A group of killer whales are visiting the southern California coast for what researchers say is probably nothing more than their own family vacation.

The orcas, also known by the nick name of killer whales, were first spotted Sunday off the coast of Rancho Palos Verdes.  The group had made its way down the coast as far as Dana Point on Tuesday. By this morning, they were back up in Rancho Palos Verdes close to shore.

"My opinion is that they took a family vacation down the southern California coast," said killer whale researcher Alisa Schulman-Janiger. "Every time I see them it's exciting. Every time it's like the first time."

Schulman-Janiger has been studying whales since 1984, and has distinguished this group of 10 whales as two different families. While  Schulman-Janiger has been tracking them, the most alarming notification came this morning. She received a call that part of the killer whale group had attempted to attack a grey whale.

"A single grey whale headed straight towards them, and the killer whales went right up to it," said Schulman-Janiger. As the killer whales attempted to surround the grey whale, it then headed straight into kelp as a defense maneuver, she said.

"They were trying to launch an attack or practice attack for the calves," said Schulman-Janiger. "It doesn't look like the grey whale is injured at all."

Shulman-Janiger has not seen orcas attack a grey whale in 28 years, and claims they usually attack when the grey whale is migrating south with a calf. That doesn't mean the killer whales haven't had a feast on their vacation. Schulman-Janiger says sea lions have been their delicacy.

"While I was out on Monday on the water, they probably ate at least five sea lions in five hours," said Schulman-Janiger. "That's really their normal food."

Donna Wharf, general manager of Dana Wharf Sports Fishing and Whale Watching, went out to see the killer whales Tuesday. She says the experience was something she couldn't describe in words.

"To watch the orcas in the wild is something that you…it's just breathtaking. It's so beautiful," Wharf said.

One of the orcas, labeled CA51 for identification, was first photographed by Schulman-Janiger in 1991 in Monterey, Calif. In 1997, this group of orcas relocated to Mexico, and since then, CA51 has head up the California coast several times. Schulman-Janiger, who has been studying and photographing killer whales since 1984, says she has seen CA51 at least a dozen times since 2008.

"I tracked them and follow the movements throughout the year," said Schulman-Janiger. "I do that by identifying the shape of the fin. They have notches in them. Also the grey area called the saddle behind the fin and a white patch above the eye, that's how I can tell killer whales apart."

Researchers say these sightings are not unusual, but not as common as seeing grey whales. They hope to keep track of the killer whales as they continue their travels around southern California.