Like other migratory animals, the elephant seal has an annual pattern of behavior. That pattern is reflected in the beach population. Each animal comes to the beach twice a year for approximately one month each time, with two exceptions discussed below. While the animals are at the beach they do not eat.

Except for the young of the year, every seal comes for the molt - a period during which they grow new skin, shed their old skin, and rest. When they arrive for the molt is determined by their sex and age with the juveniles and females coming relatively early in the molt period followed by the subadult males and then by the adult males. While most of the time they are in the rookery is spent on the beach, the males will occasionally go out into the shallow water in the protected rocky areas to spar.

The second visit to the beach is either during the fall when the juveniles, young of the year, and subadults haul out on to the beach for a rest. The adult animals come on to the beach in the winter for the birthing and breeding season with adult males arriving in late November or early December when they contest for a dominant position on the beach. Winners in that contest are referred to as alpha males or beach masters.

The males are followed by the adult females in mid-December to late January. As they come on the beach they become, in effect, part of a "harem" controlled by one of the alpha males. It is likely that the females select where they come ashore not by the alpha but by the quality of that section of beach, in particular how safe it will be for the new pup.

They give birth to their pup within a few days of their arrival on the beach and nurse them for approximately four weeks. Toward the end of the nursing period the females go into estrous and are bred, usually with the alpha bull although other males will attempt to mate as the opportunity arises. Shortly after the mating and at the end of the nursing period, the female will go back to sea.

The new pup whose mother has left, now called a weaner, will remain on the beach until most of the adults have departed and then utilize the shallow waters amid the rocks to frolic, to learn how to swim, and to develop his or her muscles before making their first trip to sea. This period may last up to two months.

The two exceptions to the one month beach stays are the new pups and the adult males. The pups may be at the rookery for as much as three and one-half months. They nurse for a month and then after being weaned spend another two to two and one-half months at the rookery before taking off on their first foraging trip. The adult males also are on the beach for three to three and one-half months during the birthing-breeding season, losing approximately one-third of their body weight.

While the mother seal is on the beach only four to five weeks, she also loses about one-third of her body mass as she gives birth and nurses a pup to over 300 pounds while also nourishing herself with her metabolized blubber. Indeed, while the weight of the new born pup as a fraction of the mothers weight is similar to that for humans, at the end of four weeks the pup weighs about one-third as much as the mother, a ratio that doesn't happen with human babies for several years.

The calendar graphs show the number of seals at the rookery peaks three times during the year: in late January when most births have occurred, in late April at the peak of molting, and in late October during the fall or juvenile haul-out.