PESCADERO, Calif. (AP) — Elephant seals have returned to Año Nuevo State Park for the winter breeding season, drawing wildlife watchers to one of the largest mainland breeding rookeries on the West Coast.

Park officials said about 10,000 elephant seals arrive each winter to fight, mate and give birth. The annual spectacle at the park runs from mid-December through March, when the area is busiest with visitors looking to watch the seals on shore.

During what park docent Laura Stern called “pupping season,” bull seals engage in bloody battles for breeding access to females. Stern said “So most elephant seals come back to the same beach where they were born,” adding, “And we have about 10,000 elephant seals that come to Año Nuevo.”

Stern described the size and scale of the males as well, saying bull seals can reach up to 16 feet (4.9 meters) in length and weigh up to 2.5 tons. Visitors who come during the season book docent-led guided walks to watch the long-nosed bull seals clash on the shore, hear the barks and bellows and see mothers nurse pups on the sand dunes.

The park’s winter viewing also centers on the young seals, with mothers nursing 75-pound (34-kilogram) pups as they arrive. One visitor, Carrie Kahn, said it was “awe-inspiring,” and described the animals as both large and quick—“they’re honking and making noises.”

The public fascination comes alongside a conservation story that goes back to the 1800s, when elephant seals were hunted nearly to extinction for their blubber, which was used to make oil. In 1892, fewer than 100 animals remained on a small island off the coast of Baja California, and Mexican authorities extended legal protection to the species in 1922, followed shortly by protection in the United States.

Stern said the population has since grown to an estimated 250,000 seals living in the Pacific. She also said there is a genetic bottleneck because they are all coming from the same 30 to 60, but added that “so far they’re doing really well, and we haven’t had any problems.”

Stern described what drives the behavior seen on the beaches, saying male elephant seals have the highest level of testosterone of any mammal and telling visitors, “So they want to mate, fight, eat, press repeat.” She also urged people to see the animals up close, saying, “You’re not at a museum. You’re not in an aquarium. You are right here watching them live doing what they do.”

The park says no tours are needed to visit the seals between April and November. During the pupping season, visitors must reserve a spot on a docent-guided walk, with reservations available at www.reservecalifornia.com.