Gentoo Penguin

gentoo

Photo courtesy of National Science Foundation

Pygoscelis papua

Status (IUCN v3.1)

Near-threatened

Distribution

Gentoo

Gentoo

Population Trend

Gentoo

Descriptive Characteristics

Plumage

Adult: Male and female Gentoos are characterized by the white band or crown that extends across the top of their head from one eye to the other. There are also small white spots on the top of the head behind the crown.

Juvenile: Juvenile Gentoos are similar to adults, but the chin and throat are not black. Black plumage is sprinkled with small white spots, and the white eye ring may not be fully developed.

Chick: Gentoo chicks are primarily dark grey on the head, nape of the neck, and on the back and upper side of the flipper. The abdomen, throat and underside of the flipper are white. There is more white visible at the edge of the flipper on the chicks than on the adults.

Measurements

Differences between adult male and female gentoo penguins are limited; females are smaller over all with lower average weight, bill depth, and flipper length. There are no marked differences in plumage.

Males

Weight: 6 kg
Height: 75.0 cm
Beak: 5.5 cm
Flipper: 23.4 cm

Females

Weight: 5.6 kg
Height: 75.0 cm
Beak: 5.04 cm
Flipper: 22.2 cm

Vocalizations

Gentoos have three types of vocalizations, the contact call, the sexual call, and the agnostic calls. Contact calls are short, chopped and low pitched sounds. There are three types of sexual calls: (1) the ecstatic call is a loud trumpeting call with the four phrases ah aha aha aha, (2) the mutual display calls have shorter phrases and are less regular than the ecstatic call, and (3) the bowing call is a short hissing sound that is repeated many times. The agnostic or threat calls occur during low intensity interactions between penguins and are usually hissing or grunting sounds.

Breeding Biology

Gentoo

Average Arrival Date:  September 5
Average Egg Laying Date:  October 1
Incubation Period: 35 days
Second Clutch: Replacement clutches infrequently laid in Southern locations. If laid, they are on average 40 days after failure of first clutch. Northern locations have a wide range of laying dates (June – November) so relaying of clutches is more frequent, may occur 11 – 40 days after first failed clutch.
Chick Rearing Period:  65 days
Fledging Period:  February 1- March 30
Average Annual Reproductive Success:  0.90 chick/nest
Nest: Platform of stones, up to 10 – 20 cm high and 45 cm across, with small nest cup made up of smaller stones and sometimes vegetation. Nests in southern colonies are mostly stone, whereas nests in northern colonies are mostly vegetation. These nests can be made on Azorella hummocks or tussocks of Poa.
Age at First Breeding: 2 years
Egg Weight: 127.08 grams
Egg Length: 6.75 cm
Egg Breadth: 5.79 cm
Molt: Post-nuptial (Southern locations: mid-Dec to Feb; Northern locations: Jan) and pre-molt at sea last between 15 and 21 days.

Prey

Euphausiids, squid, small fish (100 to 125 mm long), shoaling fish (Notothenia), some crustaceans

Predators

Southern sea lions and leopard seals prey on adults and juveniles at sea. On land, giant pretrels eat adults and juveniles as well as chicks. Skuas, sheathbills, Dominican gulls and striated caracaras prey on chicks and eggs at land.