Love the Wild: Gentle Gentoo Penguins

Fossil Huntress — Palaeo Sommelier

Gentoo Penguins with their black, white natural colouring akin to formal wear — are some of my favourite animals.

They are foraging predators — dining on crustaceans, fish and squid in the cold nearshore waters of the Antarctic Peninsula, Falkland Islands, South Georgia and Sandwich Islands. South Georgia, the South Sandwich Islands and the Falklands are inhospitable British Overseas Territories in the southern Atlantic Ocean.

The first scientific description of these romantic seabirds was done by Johann Reinhold Forster in 1781. He used the Falkland Islands population for both the type specimen and locality. These diminutive penguins are in the genus Pygoscelis, and are most closely related to their penguin cousins — the Adélie and Chinstraps.

The gentoo penguin is one of three species in the genus Pygoscelis. Mitochondrial and nuclear DNA evidence suggests the genus split from other penguins around 38 million years ago, about 2 million years after the ancestors of the genus Aptenodytes.

In turn, the Adelie penguins split off from the other members of the genus around 19 million years ago, and the chinstrap and Gentoo finally diverged around 14 million years ago. Two subspecies of this penguin are recognised: Pygoscelis papua papua (the subantarctic Gentoo) and the smaller Pygoscelis papua ellsworthi (the Antarctic Gentoo).

We will likely need to reclassify the gentle Gentoos into a species complex of four morphologically similar but separate species: the northern gentoo penguin (P. papua sensu stricto), the southern gentoo penguin (P. ellsworthi), the eastern gentoo penguin (P. taeniata), and the newly-described South Georgia gentoo penguin (P. poncetii).

We find breeding colonies of gentoo penguins on ice-free surfaces either directly on the shoreline or far inland. They prefer shallow coastal areas and often nest between tufts of grass. In South Georgia, breeding colonies are 2 km inland. In colonies farther inland, where the penguins nest in grassy areas, they shift location slightly every year because the grass will become trampled over time.

Gentoos breed on many sub-Antarctic islands. The main colonies are on the Falkland Islands, South Georgia and the South Sandwich Islands, and Kerguelen Islands; smaller colonies are found on Macquarie Island, Heard Islands, Crozet Islands, South Shetland Islands, and the Antarctic Peninsula. Their breeding populations number well over 600,000 birds. Once a breeding pair decide that their romance is a go, they stay together for life — and infidelity is frowned upon. Punishment is banishment from the colony — strict but these birds know how to draw a firm line in the pebbles.

Nests are usually made from a roughly circular pile of stones and can be quite large — up to 20 cm (7.9 in) high and 25 cm (9.8 in) in diameter. The chosen rocks are prized and jealously guarded. Just who owned which pebble is the subject of many noisy debates — some escalating to nasty physical altercations between disagreeing parties. "That rock is mine. Mine!"

The pebbles are especially prized by the females, to the point that a male penguin can woo his lady love and secure a lifetimes' devotion by proffering a particularly choice stone — not unlike some human females.