From 1947 to 2008, the glacier area on Heard Island decreased by 20 per cent. Since 2008, only relatively little data are available for the assessment of the glaciers on the island, but further evidence of glacial retreat has been observed. Introduced vertebrates, such as cats, rats, mice and rabbits, previously caused a major deterioration of the natural heritage values of Macquarie Island. There was significant predation of native species until feral cats were eradicated in 2002. Overgrazing by European rabbits caused an increase in landslides, many of which damaged seabird colonies. A large-scale eradication program completed in 2014 successfully eradicated rabbits, rats and mice from the island.