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Unstable Ice Causes ‘Catastrophic Breeding Failure’ for Penguins

Climate change may be contributing to the penguin population crash at Halley Bay which is “unprecedented in the historical record.”

by Becky Ferreira
Apr 25 2019, 4:20pm

Emperor penguins at Weddell Sea. Image: Hannes Grobe/AWI

One of the world’s most important emperor penguin colonies has suffered a “catastrophic breeding failure” since 2015, according to a study published Thursday in Antarctic Science.

Warming global temperatures may be contributing to the collapse at Halley Bay colony in Antarctica by melting ice shelves that birds need to hatch and raise their chicks.

Geospatial scientist Peter Fretwell and conservation biologist Philip Trathan, members of the British Antarctic Survey and authors of the new study, said the colony’s prolonged reproductive failures are “unprecedented in the historical record.”

“Although the recorded population has varied, the colony is consistently the largest in the Weddell Sea, over twice the size of any other colony in the region,” the team said in the study. “There have been no previously recorded instances of total breeding failure at the site.”

For years, Halley Bay attracted anywhere between 14,000 and 25,000 breeding pairs, representing about eight percent of the world emperor penguin population.

But everything changed in September 2015, when extreme storms battered Halley Bay and began breaking up its sea ice at an accelerated rate. The intense weather was likely propelled by an unusually strong El Niño warming event that occurred from 2014 to 2016. As warm ocean waters circulated through the Weddell Sea, they caused a record low amount of sea ice at Halley Bay.

Fretwell and Trathan observed the fallout of this abrupt environmental shift using high resolution satellite imagery. It’s possible to estimate penguin populations from space by examining the enormous stains left by their guano.

The team discovered that the colony had “almost no breeding success” in 2016, 2017 and 2018. Satellites also revealed evidence that the affected birds started resettling at the nearest breeding grounds, the Dawson-Lambton colony, which is located 34 miles south of Halley Bay.

The population of the Dawson-Lambton colony has increased elevenfold in recent years, from 1,280 breeding pairs in 2015 to 14,612 pairs in 2018.

Though some of the Halley Bay penguins are finding a new stronghold, the regional population of penguins likely declined due to the loss of at least three consecutive breeding seasons at such an important site.

Climate change may play a role in these colony disruptions, but the exact connections between warming global temperatures, Antarctic ice shelf dynamics, and El Niño cycles are still a matter of active research.

Still, Fretwell and Trathan think that the collapse of the Halley Bay colony will be a useful case study to watch to inform the future of these vulnerable colonies.

“Understanding how emperor penguins react to catastrophic sea-ice loss will be of crucial importance if one is to predict the fate of the species over coming decades,” the team said.

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