Elephant Seal

Fact Sheet

Scientific name: Mirounga leonina

Description: It is the largest seal, with males weighing around 4-5 tons and measuring up to 6 meters, whereas females are smaller, at 900 kg and 3.5 meters long.

Calves are born in September, after a 10 months gestation. Pups are 1.3 meters long birth, and weigh 35 – 40 kg. Females lactate for a relatively brief period (23 days) during which the pups gain 5 kg per day and, at the time of weaning, they have increased their initial weight 300%.

20 days after giving birth, females mate again and a few days later they leave the beach, weaning their pups abruptly

Annual Cycle

The annual life cycle of the southern elephant seal comprises two periods on land during which they do not feed: reproduction and molting and two pelagic periods feeding at sea.

First Land Cycle: Reproduction

This cycle starts in the third week of August, when the first males arrive too Valdes Peninsula coast. During the reproductive period, females remain in the shore for 30 days, and males between 60 and 70 days.

Calves are born in September, after a gestation of 10 months. They are breastfed for an average period of 23 days during which they gain 5 kilograms per day. 20 days after giving birth, females are fertilized again and leave the beach, forcing weaning.


Generic name Mirounga is based on the name with which the Australian aborigines designated these animals, the name leonina derives from the Latin leoninus (similar to a lion) which refers to the roaring-like sounds that males produce mainly at the time of heat.

The elephant seal is the largest pinniped species. The most striking characteristic of this specie is the pronounced sexual dimorphism, with males weighing 5 times more than females.

This seals have large blocky heads, strong front flippers used to steer while they swim, and rear flippers used for propulsion. Complementing their tremendous bulk is the inflatable trunk-like proboscis of the bull.

Elephant seals spend most of the year at sea traveling thousands of miles and making long, deep dives to feed on fish and squid

First pelagic cycle: Post-breeding foraging period

After the reproductive period, the elephant seals stays for 70 – 75 days in the ocean, after which they return to shore to shed their fur.

Elephant seals spend 90% of their time under the sea and are the deepest diving air-breathing non-cetaceans.

They regularly dive to 400 meters and have been recorded at 1,500 meters.

They can stay more than two hours underwater.

They feed on fish and cephalopods.

Second land cycle: Molting

Unlike other mammals, the molting process is so abrupt in the elephant seal that it is called a catastrophic molt. Each elephant seal will stay ashore for about twenty-five to twenty-eight days in order to shed all of its fur.

The fur sheds in patches with the epidermal skin attached revealing a new dark gray fur underneath.

They need to stay in land because they are more sensitive to heat loss

Second pelagic cycle: Post-molting period

This is the longest foraging trip, that lasts 7 – 8 months from February to September – October. Most of the gestation period of female elephant seals takes place in the open sea, when they are foraging and they not only obtain energy for themselves but also for the growing calf and to obtain fat reserves for the 3 weeks of lactation, during which she will remain fasting on the shore.

This is the reason why it is very important for females to have a productive post-molting foraging period: the reproductive success of that year and the future of the pup relies on the success of the feeding journey. In the post-molting phase, the females feed in the Argentine Basin and the males in the continental shelf.

South American
Sea Lion

Fact Sheet

Scientific Name: Otaria flavescens

Description: Males can grow up to 2.7 m and weigh 350 kg. Females are 1.8 – 2 m long and weigh about 150 kg. Calves weigh 10-15 kg at birth and are 85 cm long.

Males have a very large head with a well-developed mane. Females body is smaller and more stylized. Either males and females fur is orange or yellowish brown or brown with upturned snouts. Pups are born black and molt into a chocolate color when they are 2 months old. Females give birth to one calf per season, delivery occurs between 3 and 5 days after they arrive to the colony, after 12 months of gestation. Lactation lasts between 8 months and a year, although it can happen that females breastfeed simultaneously a newborn puppy and one born in the previous season. Females reach sexual maturity at 4-5 years and males between 4-6 years, but they can only fight to defend a territory and maintain a harem at the age of 9. Females can live up to 22 years and males up to 19.


The scientific name derives from the Greek otarion (small ears) and the Latin flavus (yellowish). Difference between this specie and other sea lions is the size (it is the largest otarian in the region) and by the “leonine” physiognomy of the adult males that have a dense mane on their head, chest and neck.

Sea lions have an annual cycle that consists of a short reproductive period ashore, and a marine period where they alternate feeding trips at sea and resting trips on the coast.

The reproductive season takes place from December to February and the peak of births occurs in mid January.

Where to watch them

South American sea lions can be found throughout the year in the different beaches of Valdes Peninsula. They can be admired from Punta Piramide Reserve, from the trails of Punta Norte, on boat trips or on kayak excursions.

Males start to arrive at the reproductive colonies fin early December, to take over a territory that they will defend aggressively while waiting for females to arrive.

Aggressive behavior between males occurs with little physical contact and consist mainly of threatening postures and roars, although they can sometimes injure themselves.

Each male gets his harem, that does not exceed 10 females, although they always try to «steal» females from other males.

Females deliver few days after their arrival and are receptive again a week after giving birth, when they are copulated by the males who have successfully held a place in the colony. The colony’s reproductive activities end towards the end of February, when only the females remain with the calves they will nurse for 8-12 months.

Magellanic Penguin

Fact Sheet

Scientific Name: Spheniscus Magellanicus

Description: Magellanic are are medium-sized penguins which grow to be 61–76 cm (24–30 in) tall and weigh between 2.7 and 6.5 kg (6.0 and 14.3 lb).

Their weight varies between 1.8 kg near starvation and about 6 kg at the beginning of the molt. Males are larger than females, and the weight of both drops while the couple raises their young. Individuals have distinctive calls that allow couples to recognize each other. Couples fight over their nesting site. Most pairs reproduce under the bushes, or caves they dig to protect the nest from bad weather and predators. The nest is usually hollow, and the penguins place some stones, feathers, bones and sometimes algae inside. The laying is of two eggs, which both parents take turns to hatch.


Adult penguins have black backs and white bellies, and a broad crescent of white feathers that extends from just above each eye to the chin, a horseshoe-shaped band of black feathers that cuts across the white feathers on the chest and abdomen, and a small but noticeable region of pink flesh on the face. It generally has two black bands on the throat, although it can vary between individuals, and an inverted U-shaped black band extends from the chest down on each flank. These bands on the sides of the body can confuse fish, disperse shoals, and improve prey capture.

Where to watch them

Reproductive period Penguins arrive to the reproductive colonies on the coast of Chubut in early September. Magellanic penguins mate with the same partner year after year. Males arrive first to claim their nesting site (also known as burrow) from the previous year and waits to reconnect with his partner. Females arrive a few days later. They are able to recognize their mates through their call alone. Females generally lay two eggs at the beginning of October and after 40 days of incubation shared with the male the chicks are born, covered by a dark gray feather coat, which they will lose in February after molting. At this time they become independent and start to swim in search of food.

Molting period

At the end of January and February, groups of juveniles born the previous season spend almost two weeks ashore changing their juvenile feather coat for that of adult. During the molting period, the feathers are not waterproof and the birds need to stay on land. At these times they are particularly vulnerable to land predators and interference. As they cannot feed during the molt they feed intensively prior to molting and store body fat to survive the loss of up to half their body weight.

In Peninsula Valdés there are two large colonies in Caleta Valdés and in Punta Norte. The Caleta Valdés penguins colony can be accessed with the entrance to the Park, the Punta Norte colonies can be visited by paying a separate fee in the case of San Lorenzo, or spending a night at Estancia La Ernestina.


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