Possums aren’t the gentle vegetarians you thought they were
We now have ample evidence of these cute marsupials’ taste for flesh – and they could be endangering some of our most threatened birds.
Tim Low lives in a state of perpetual surprise at everything wild and alive. His response is to write searching books, Australian Geographic articles and this blog. His book Where Song Began (Penguin, 2014) recently became the first nature book ever to win the Australian Book Industry Award for best general non-fiction. Tim’s newest book is called The New Nature.
POSSUMS EAT FRUIT, right? When they sneak into the kitchen at night it is the fruit bowl they go for. In wildlife books possums and gliders are portrayed as gentle vegetarians keen on leaves, flowers, nectar and fruits, with a few insects sometimes taken as well.
But in New Zealand, where brushtail possums were imported long ago for the fur trade, remote cameras have revealed they like meat, showing them killing and eating robins, honeyeaters, keas and other parrots, and even adult kiwis. They consume eggs and chicks as well, worsening the decline of some rare species. They are thought to be one reason the South Island kokako appears to be extinct. They have also been seen eating rare snails and trying to catch small bats at their roosts.
In Australia their appetite for flesh came to light on Kangaroo Island during studies of a rare population of the glossy black-cockatoo. Metal collars had to be put on tree trunks to stop possums climbing into nest holes to feast on chicks and eggs.
Now that motion-triggered cameras have become a regular method of monitoring nests at night, our gliders have been outed as carnivores as well. In Tasmania, biologist Dejan Stojanovic found that in some forest remnants no swift parrots were raising young and about half the females were dying. The culprits were sugar gliders, one of our cutest marsupials. They are known to also prey on endangered orange-bellied parrots and forty-spotted pardalotes. Dejan concluded that sugar gliders represent ‘a severe threatening process’ for endangered swift parrots.
A sugar glider is caught on camera about to enter a swift parrot nest in Tasmania. (Image: Dejan Stojanovic)
Sugar gliders were imported from the mainland into Tasmania as pets in the 1850s, but this, on its own, does not explain why there is a problem. On the mainland they are guilty of preying on another endangered bird, the regent honeyeater. And the squirrel glider, another cute marsupial, was filmed trying to catch a regent honeyeater at the nest and settling for her eggs instead:
Source: BirdLife Australia / Youtube
Even our tiny pygmy possums like meat. They prey regularly on fairy martins, entering their nests at night.
Possums and gliders are now recognised as a serious conservation concern. We can assume that killing at bird nests has always gone on, becoming unsustainable for species under pressure for other reasons such as habitat loss. In Tasmania, sugar glider predation is worst where swift parrots nest in fragmented forests.
Our possums and gliders have been thoroughly misunderstood. At night with a spotlight I have often watched them in trees, as others have, without guessing that their tastes go far beyond leaves, fruits and nectar. A glider entering a tree hole was thought to be entering its den, when it is more likely to be seeking a meal of flesh and eggs.
We shouldn’t stop liking our possums and gliders, but we should think of them as avid omnivores, with a liking for animals as well as plants.
No one wants to kill possums or gliders, but losing species is worse. In New Zealand, where brushtails also defoliate trees, millions are poisoned and shot. In Tasmania some culling of sugar gliders is now going on.