The small penguin species include the Adelie Penguin Pygoscelis adeliae, the Gentoo Penguin Pygoscelis papua, and the Chinstrap Penguin Pygoscelis antartica. Chinstrap, Gentoo, and Adelie penguins all belong to the Pygoscelis genus of penguins, which means
brush-tailed or long-tailed penguins. All three of these species are about the same size.
The chinstrap penguin was formerly almost entirely confined to the South American guadrant
of Antarctica but they have increased and spread east to the Balleny Islands in the Ross Sea sector. There are now
more than seven million pairs of Chinstrap penguins. Some scientists think that this increase might
be a result of the decline in the number of plankton-feeding whales or as a response to climate change.
Chinstrap and Gentoo penguins are different from the Adelies and Emperors in that
although all four of these penguin species are considered the most southern of all penguins, only Adelies and Emperors actually breed on the continent itself. Chinstrap and Gentoo penguins both penetrate south of the Antarctic Convergence, but their breeding grounds are further to the north. Chinstraps breed on the islands around the continent and some are found on the islands close to the Antarctic Convergence.
Chinstraps always nest on rocky ground, and they build their nests out of pebbles. Chinstraps have a diet that consists almost entirely of krill. They are very noisy and aggressive.
