Australasian Science: Australia's authority on science since 1938

Sugar Gliders Identified as Parrot Predators

The endangered swift parrot is more likely to be killed and eaten by sugar gliders in Tasmania in areas where forests are disturbed or lost compared with areas of intact forest, according to research published in Diversity and Distributions.

The research took place over a 3-year period, and compared populations of swift parrots from mainland Tasmania where sugar gliders also live, to those on islands where sugar gliders are absent.

“Across the Tasmanian mainland, we found a link between deforestation and increasing predation on parrot nests by sugar gliders,” says Dejan Stojanovic of the Australian National University. “On offshore islands where sugar gliders are absent, no swift parrot nests failed due to predators, whereas on the Tasmanian mainland, sugar gliders caused the failure of 83% of swift parrot nests, and in most cases the adult female parrot was also killed and eaten.”

Stojanovic says that predation of swift parrots and their nests could be as high as 100% in locations where forest loss was severe. However, survival of parrots and their nests improved as the cover of old-growth forest increased.

The research is the first to identify sugar gliders as the primary cause of mortality for any bird. “Up until we did this research it was assumed that gliders were only nectar and insect feeders,” he said. “Other studies had found that gliders occasionally eat birds, but nobody expected that their impacts could be this severe and widespread.

Sugar gliders are native to the Australian mainland but were introduced into Tasmania in the 19th century.