Significant decline of endangered Antipodes Island penguins: Is extreme weather an additional impact?

Abstract

Abstract Worldwide, most crested penguin species (Eudyptes spp.) are in decline. New Zealand's subantarctic Antipodes Islands are of international significance for erect‐crested (Eudyptes sclateri) and rockhopper (Eudyptes filholi) penguins. Between 1995 and 2011, a 23% decline was recorded in the two penguin species on the Antipodes Islands. In October 2014, nest abundance counts on Antipodes Island were undertaken to determine if this decline was continuing, particularly in light of a significant storm event that hit the Antipodes area in January 2014 causing massive landslides during the penguin breeding season. All penguin colonies ground counted in 2011 were preferentially ground counted in 2014 or, if time or weather did not allow, were checked with binoculars to confirm colony presence or absence. Seventy‐three per cent of the colonies and the equivalent of 82% of all nests counted in 2011 were recounted in 2014. Overall, there was a 19% decline in erect‐crested penguin nests between 2011 and 2014. Rockhopper penguins showed a slight increase (2.6%). Landslides affected 11% of the main islands’ land area and 44% of surveyed nesting colonies. Erect‐crested penguin colonies with approximately 75% or greater of their area impacted by landslides showed a significantly greater decline than unaffected or only partially impacted colonies. Landslides showed a minimal effect on rockhopper nest numbers. There continues to be a significant decline of erect‐crested penguins at the Antipodes Islands. An increasing occurrence of extreme weather events are predicted with climate change and have the potential to increase land‐based flooding and landslides, adding additional impacts to terrestrial breeding marine species. Greater understanding of what is causing erect‐crested penguin decline is needed to prevent this endangered species from extinction.