There is nothing straightforward and typical about massive walrus haul outs in Alaska, which have become an annual event as sea ice retreats earlier each summer. An ongoing haul out event at Point Lay, Alaska, has featured thousands of walruses one day, followed by none a few days later, and now tens thousands again.

In fact, this haul out may be nearing a record for the U.S., if the numbers keep increasing.

As of Friday, there were about 35,000 walruses in two separate haul out events in the tiny community of Point Lay, Alaska, on the Chukchi Sea, the Fish and Wildlife Service says.

See also: 14 photos that show how drastically global warming is changing Alaska

This is similar in scale to what occurred in the same location in 2014, but earlier in the year, leading experts to speculate that the number will increase as sea ice continues retreating for another few weeks.

To get to the beaches, and then from the beaches to the sea ice pack hundreds of miles offshore, the walruses are transiting the area where Shell is drilling for oil in the Arctic, potentially exposing themselves to harm from pollution, underwater seismic blasting, surface shipping and other drilling activities.

Here's what's known so far, including new information provided to Mashable from federal government scientists.

In mid-to-late August, local residents of Point Lay reported the presence of hundreds to thousands of walruses on a local beach, where past haul out events had occurred. Such events take place because of global warming-related sea ice loss, which deprives Pacific walruses of the ice cover they need for hunting, resting and mating.

Aerial photography confirmed the sighting, and crude estimates put the number of mammals present in the thousands. It was assumed that the numbers of walrus would continue to grow with time, as the sea ice continued to melt until mid-to-late September.

Aerial photograph of thousands of Pacific walrus coming ashore near Point Lay, Alaska on August 23, 2015. Image: Gary Braasch

Animation of USGS-tagged walruses (yellow dots) the Shell oil leases (green area) and the sea ice cover (white shaded area).

Sea ice retreat in the Chukchi Sea this season was particularly rapid and extreme this year, according to the National Snow and Ice Data Center in Boulder, Colorado.

But the buildup in Pacific walruses did not continue.

Instead, on August 30, after a major storm blew through the area, local residents took a boat out to the barrier island where the walruses had hauled out, and were shocked to see none were present, according to Jonathan Snyder, a wildlife biologist with the U.S. Fish and Wildlife Service in Alaska.

Snyder thinks the storm, which brought high winds, heavy rain and pounding surf to Point Lay on August 28 and 29, may have caused the walruses to flee the beach.

"My guess is that because of surf pounding the beach, they decided to head out to sea to ride it out," Snyder said in an interview.

He says it's unknown what the consequences of this will be for the many young calves present, since they may have grown weary and weak with time as the storm continued.

As of Thursday morning, many walruses were returning to the same spot, according to Andrea Madeiros, a Fish and Wildlife Service spokeswoman. And on Friday, the number of walruses far outranked the number of people in Point Lay, at approximately 35,000 to 264.

"The village reported that there were a large number of animals back onshore," Madeiros told Mashable. The walrus were visible further back from the waterline, according to community members reporting to FWS. "The impression was that's because there's a lot of animals there... it's kind of like they're spilling over."

Aerial photograph of thousands of Pacific walrus coming ashore near Point Lay, NW Arctic coast of Alaska on August 23, 2015. This is one of the earliest known haul outs, which have occurred increasingly as Arctic sea ice melts faster and covers less of the sea. Image: Gary Braasch

Female Pacific walruses and their young forage over the shallow continental shelf of the Chukchi Sea in U.S. and Russian waters during the summer, relying on the sea ice as resting platforms between foraging trips. They haul out in Alaska and Russia when sea ice recedes past the shallower continental shelf waters and into the deeper Arctic Basin, where feeding is more difficult.

In recent years, U.S. Geological Survey has attached GPS tracking beacons to some of the walruses, and these show that each day, some of the mammals are trekking hundreds of miles off the coast in search of ice cover that exists over deeper water, across an area known as the Hannah Shoal. Presumably, they are hunting there, even though the water is extremely deep.

"They have to feed," Snyder told Mashable. He says it's not yet known what the impact of such long-range trips, during which the walruses burn large amounts of energy, is on these mammals.

"That is the big question," he said.

The USGS is planning to deploy a small drone to the Point Lay area in the near future to try to get a more accurate count of the number of walruses on the beach, but this official count may take weeks, and require great care to complete.

During large haul out events, airspace restrictions are put into place to avoid spooking walruses by aircraft flying too low over their haul out locations, which can cause deadly stampedes back into the water. In 2014, about 60 walruses died because of the population density involved, the USGS stated.

In addition to the difficulties involved in deploying the drone in such a remote location, Snyder says, "It's very tedious to count all the individual walruses in a picture."

The fact that there are so many walruses on the shore in Point Lay likely points to the existence of other haul out sites in Alaska and the Russian Arctic, Snyder says, noting that in the past, up to 100,000 walruses have hauled out in Russia when the sea ice cover dwindled away.

Walruses are transiting through Shell drilling sites

Tracking beacons attached to some Pacific walrus show that they are transiting through the controversial Shell exploratory drilling sites off the Alaskan coast. Shell operates under a Letter of Authorization, or LOA, with the Interior Department, which allows them to incidentally take, or kill, some Pacific walruses and polar bears during the course of their operations, but imposes requirements on the company to minimize any disturbances of these marine mammals.

For example, with Pacific walruses, Shell is required to have certified marine mammal observers on each of their platforms and ships to detect the presence of these mammals. Those observers, Snyder says, have been reporting walruses in the vicinity of the two drilling rigs and support vessels.

According to the LOA, Shell is not allowed to conduct drilling operations or seismic surveys if walruses are spotted within a half-mile radius on sea ice, 1-mile radius on land, or if 12 or more walruses are seen within a half-mile of Shell's equipment in the water.

The LOA states: "Vessels may not be operated in such a way as to separate groups of 12 or more walruses encountered in the water."

In response to a query from Mashable, the Interior Department, which oversees the Fish and Wildlife Service, said Shell is following "regulations that have been in place and public for over two years and designed to provide for the least practicable adverse impact on walrus and polar bears." The department noted in a statement that one of the measures included in the LOA is the requirement that Shell maintain a 15-mile buffer between drilling rigs while drilling operations are taking place.

The Shell leases have become a flash point in clashes between environmental organizations and the Obama administration over whether to allow Arctic drilling at all, given the administration's focus on reducing the severity of global warming.

Given that the company is likely to continue exploratory drilling for a few more years, and potentially move into active oil production after that, barring regulatory or legal action to stop it, the walrus encounters with Shell assets will also continue, with unknown consequences.

As with ecosystems throughout the rapidly changing Arctic, the Pacific walrus is increasingly moving into uncharted territory.