If your social media feeds have suddenly lit up with images of orcas on the Oregon Coast, it’s not that the marine mammals have suddenly arrived, it’s that people are suddenly paying closer attention.

Orcas, also known as killer whales, have long visited the shoreline of Oregon, most there to feast on pinnipeds like harbor seals and sea lions. But unlike watching the masses of migrating gray whales, spotting orcas is a lot harder, making their visits seem more rare.

Some researchers in the Pacific Northwest are hoping to change that by crowdsourcing videos and photos of orcas on the Oregon Coast, in order to get a better idea of the population sizes and behaviors of the apex predators.

Josh McInnes, a marine mammal scientist with the University of British Columbia, is one of the researchers behind a Facebook group called Oregon Coast Whale Watchers, a community that gathers documentation of marine mammals. Recently, the page has been filled with images of orcas, seen from Brookings to Newport and beyond.

“Just because we don’t hear about sightings doesn’t mean the killer whales aren’t there,” McInnes said. “They rely on stealth to hunt, so they’re very quiet at the surface.”

Gray whales, which are much larger animals and are known for their distinctive spouts, curved backs and regular appearances at the surface of the water, are easier to spot. Orcas, which move much faster, are harder to spot – you may only see a tall, black fin sticking out of the water before the animal is gone.

Orcas, technically the world’s largest porpoise, are a complex species with many qualities that set them apart from other marine mammals on the Pacific coast, making them one of the most fascinating animals to watch in the wild.

In the Pacific Northwest alone, there are several different subspecies of orcas that have different behaviors, eat different food and even speak different dialects. The well-documented southern residents in the Salish Sea, for example, eat only salmon and tend to stay in one location, while free-roaming transient orcas feast on mammals and have a much larger territory.

As the apex predators of the ocean, orcas are at the top of the food chain, and have been documented hunting everything from great white sharks to blue whales, which they often do in coordinated attacks.

On the Oregon Coast, there are typically two groups of transient orcas, McInnes said: the larger inner coast population that hunts along the shoreline, and the smaller outer coast population that swims in deeper waters. In all, researchers have documented about 349 inner coast and 180 outer coast orcas, he said.

In contrast to the dwindling numbers of the southern residents, which also occasionally travel to the Oregon Coast, populations of transient orcas have been on the rise over the last three decades, in step with the rise in the pinniped population. Sea lions and seals were hunted extensively by humans in the 19th century, but have rebounded thanks to conservation efforts.

“It’s ecologically connected,” McInnes said. “You see an increase in the prey, you see an increase in predators; you see a decrease in prey, you see a decrease in predators.”