Named for the thin black band of feathers that extends from ear to ear under their heads, chinstrap penguins grow to about 2.2 feet (68 centimeters) tall, with males being larger and heavier than females. A population of chinstrap penguins in Antarctica has seen a 36 percent decline since 1991, in what researchers say is a consequence of declining krill populations. Andres Barbosa

By Jeanna Bryner, LiveScience Managing Editor
19 June 2012 A population of chinstrap penguins is feeling the heat, with more than one-third of a breeding colony lost in the past 20 years, new research finds. A warming planet, which is causing sea ice in Antarctica (and elsewhere) to melt, may ultimately be to blame for the plummeting penguin population, the researchers said. That’s because the chinstraps’ main food, shrimplike creatures called krill, depend on algae that attaches to that ice. “Actually, in the ’90s it was thought that the climate change would favor the chinstrap penguin, because this species prefers sea waters without ice, unlike the Adélie penguin, which prefers the ice pack,” study researcher Andres Barbosa told LiveScience. He added that at the time, chinstraps, named for the thin black facial line from cheek to cheek, seemed to increase in numbers, with some new colonies being established. The sea-ice decline in the winter, however, has become so big that it is now impacting krill populations, said Barbosa, of the National Museum of Natural Sciences in Madrid. Barbosa and his colleagues tallied chinstrap penguins (Pygoscelis antarctica) in the Vapour Col colony of Deception Island, in the Antarctic’s South Shetland Islands in 1991-92 and 2008-09. They photographed nests in 19 subcolonies, mainly in December when chicks were hatching. [See Photos of Chinstrap Penguins on Deception] Results, which ended up including just 12 of the subcolonies due to availability of data, showed the occupied nests had declined by 36 percent between 1991 and 2008. […] [A] dip in the krill population may be to blame, an idea supported by the fact that Adélie penguin population (P. adeliae) in the region is also declining, while the gentoo penguin population (P. papua), which has a more variable diet, is not. […]

Is global warming responsible for chinstrap penguin decline?