Adélie penguins as indicators of the state of the sea-ice in Adélie Land

In the 2013-14 reproductive season, the 26,000 pairs of Adélie penguins from Pétrel Island, Terre Adélie, failed to fledge their chicks. This catastrophic breeding failure resulted from two factors. First, the season saw an extreme sea-ice extent that forced Adélie parents to cover great distances to reach the open water during the incubation and early chick-rearing phases. The extended absence of parents meant that the partner and/or the chick fasted longer at the nest, increasing the risk of desertion by the partner and the risk of dying of prolonged fast for the chick(s). Second, the season was characterized by unusual precipitations of rain around the turn of the year that killed massively the already weakened young chicks. While we haven’t seen yet the consequences of this “zero year” on the demography of the population there, a second complete breeding failure took place in the season 2016-17, leading to the deaths of all the chicks of the 28,000 Adélie pairs that bred in this season. Once more sea-ice extent was the major cause of failure. Sea-ice conditions in 2016-17 were even more drastic than in 2013-14, as sea ice extended as far as 80 km from the colony but over the entire breeding period. Snow precipitations occurred only over 2-3 days in mid-November 2016 and several nests were buried under more than a meter of snow, but the snow falls were immediately followed by almost a week with temperatures continuously above 4°C that sent flows of melting snow through the colony, wiping out nests and eggs. Two “zero years” occurring within three breeding seasons will definitely affect the demographics of the population at Pétrels Island. Furthermore, the situation is not going to improve as long as the B9B giant berg stays anchored in Commonwealth Bay, on the east of the island. The B9B blocks icebergs from the Mertz glacier in front of Pétrel Island. This is a serious threat to the populations of Pétrel Island and a strong incentive for the creation of the D’Urville Sea/Mertz Marine Protected Area in the EARSMPA.