Evidence of mouse attacks on albatross chicks on sub-Antarctic Marion Island

Introduced house mice Mus musculus have recently been discovered to be significant predators of chicks of Tristan albatrosses Diomedea dabbenena and several burrowing petrels at Gough Island. We summarize evidence for mouse attacks on albatross chicks at sub-Antarctic Marion Island, where mice are also the only introduced mammal following the eradication of feral cats Felis canis in the early 1990s. Wounds consistent with mouse attacks have been found on wandering albatrosses Diomedea exulans since 2003 and dark-mantled sooty albatrosses Phoebetria fusca in 2009. To date, attacks on wandering albatross chicks have been infrequent, affecting < 1% of chicks in Study colonies, and only about half of the attacks have been fatal. Small chicks may also die when mouse burrows collapse under chicks, trapping them. Mouse attacks appear to be a recent phenomenon, supporting the contention that mice pose a significant threat when they are the only introduced mammal species. Ongoing monitoring is needed to assess whether the impacts of mice increase over time. Our observations add impetus to calls for the eradication of mice from Marion Island.