The genus Pygoscelis ("rump-legged") contains three living species of penguins collectively known as "brush-tailed penguins".
Taxonomy
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.
;Extant species
A 2020 study found that the gentoo penguin may actually comprise a species complex of 4 similar but genetically distinct species: the northern gentoo penguin (P. papua), the southern gentoo penguin (P. ellsworthi), the eastern gentoo penguin (P. taeniata), and the newly-described South Georgia gentoo penguin (P. poncetii). However, in 2021 the International Ornithological Congress recognized these as being subspecies of P. papua.
A 2026 study, based on the genome sequencing of ten colonies proposes recognizing four species within Pygoscelis papua:
- Pygoscelis papua in the Falkland Islands and South America;
- Pygoscelis taeniata in several groups of subantarctic islands:
- P. t. taeniata on Macquarie Island;
- another undescribed subspecies on the Crozet Islands and Marion Island;
- Pygoscelis ellsworthi with two subspecies:
- P. e. ellsworthi on the Antarctic Peninsula, the South Orkney Islands, and the South Shetland Islands;
- P. e. poncetii on South Georgia;
- Pygoscelis kerguelensis on the Kerguelen Islands and Heard Island.
;Fossil species
- †Pygoscelis grandis (Bahía Inglesa Formation, Late Miocene/Early Pliocene of Bahía Inglesa, Chile)
- †Pygoscelis calderensis (Bahía Inglesa Formation, Late Miocene of Bahía Inglesa, Chile)
- †Pygoscelis tyreei (Pliocene of New Zealand)
The latter two are tentatively assigned to this genus.
Ecology
A study has estimated that there are about 8 million pairs of chinstrap, 3.79 million pairs of Adélie, and 387,000 pairs of gentoo penguins in their particular areas, making up 90% of Antarctic avian biomass.
Niche partitioning
thumb|A chinstrap amidst gentoos, at [[King George Island (South Shetland Islands)|King George Island]]
While the three species in this genus overlap in range, Adelies can breed further south in the continental Antarctic, gentoos further north, and chinstraps intermediate between the two. Gentoos and chinstraps are less ice-tolerant than Adelies; consequentially, warming climates are causing the range of gentoos and chinstraps to expand southward and the range of Adelies to shrink.
Although all species feed almost entirely on Antarctic krill, there is niche partitioning between species. Gentoos are also more willing to forage on fish,