One of the largest colonies of emperor penguins was abandoned after the tragic end of thousands of chicks, drowned in the icy waters of Antarctica in 2016, before they could cover themselves with feathers suitable for swimming. The catastrophe and its long-term effects on the bird population were documented in an article in the British Antarctic Survey (BAS) published in the journal Antarctic Science.

A solid home. The emperor penguin (Aptenodytes forsteri), the largest and heaviest of all penguins, is considered particularly exposed to the consequences of global warming, because to reproduce and raise chicks it needs sea ice that remains stable for almost a year. In April the couples settle on the platform, in December the chicks develop the feathers suitable to face the water. If the ice crumbles first, the little ones drown.

The difficult challenges of the emperor penguin

Ancient grandeur. Apparently that's exactly what happened to the second largest colony of emperor penguins, the "home" one at Halley Bay, on the edge of the Brunt Ice Shelf, in the Weddell Sea, in Antarctica. For several decades, these glaciers have hosted between 14, 000 and 25, 000 penguin pairs of reproductive ages, 5-9% of the global population.

Swallowed by the waves. But in 2016, the winds raged on the sea ice already made unstable by El NiƱo, the periodic warming event of the Pacific that alters the earth's climate. The satellite surveys of the feathered guano, an instrument that allows to identify their presence even from 800 km away, have documented the almost total disappearance of specimens, and since then the situation has not improved. Many adults have avoided reproducing in recent years or have moved to other sites: another colony 50 km from Halley Bay seems to have expanded.

Image 2015: the guano of the Halley Bay colony visible from Space. From the following year he lost track of it. | Digital Globe

Fully exposed. The event does not seem to be directly attributable to the effects of global warming, but the sensitivity of the penguins to the instability of the ice offers a disturbing glimpse of the future of this Antarctic species, struggling with ever more unstable and reduced ice. What worries scientists is not the fate of a single colony, but the fact that one of the areas considered a safe haven for these birds showed concrete signs of instability.

According to some estimates, 50-70 percent of the emperor penguin population could disappear by the end of the century, if the sea ice becomes thinner as expected. With important repercussions on the food chain: the emperor penguins are in fact both prey (of leopard seals) and predators of krill and small fish.