An unassuming moth – with nutritional value akin to ‘pre-pregnancy vitamins’ – could hold the key to supporting a critically endangered possum back from the brink of extinction.
Researchers at Alpine Resorts Victoria are eagerly awaiting the up to 1000 km annual migration of Bogong Moths from the plains of Queensland, New South Wales and Victoria to the high country of Victoria and New South Wales, hoping this year’s moth numbers will be bountiful enough to boost the numbers of juvenile Mountain Pygmy-possums in the alps.
Bogong Moths are considered a primary food source for Mountain Pygmy-possums over spring and contain vital nutrients that aid in their successful reproduction. The moths start arriving in the alps in September just as the little possums are waking from their annual hibernation under the snow.
Bogong moths are critical for the survival of Mountain Pygmy-possums
Alpine Resorts Victoria Head of Environmental Sustainability Louise Perrin said the moths were a crucial ingredient for the possums’ maximum possible four pouch young, but drought, climate change and bright man-made light sources had impacted moth numbers.
“The moths fly into the Mountain Pygmy-possum habitat, rock boulderfields in the alps, just as the possums are waking up from their hibernation. I often say it’s like having a pizza delivered to your door,” Ms Perrin said.
“It’s critical for the female possums to have access to and eat a lot of the moths because of the high levels of fat and protein and vitamins. That helps support oestrus, pregnancy and milk production in the females so they can breed successfully.”
Ms Perrin said even though the Bogong Moth population had shown some signs of recovery, the moths had not arrived in the numbers needed.
She said research has shown that Mountain Pygmy-possums experience litter loss with pouch young failing to survive if they do not receive enough nutrients and energy, which largely comes from the moths in spring.
“Mountain Pygmy-possums do not just snack exclusively on moths, they will eat other invertebrates and seeds, but these do not give them all the energy and essentials for successful reproduction of the full four pouch young,” she said.
“We need to help as many Bogong Moths as we can get from the plains of Queensland to the Victorian alps to ensure the possums have the best chance of reproduction and survival.”
Australia's only hibernating marsupial
Mountain Pygmy-possums were thought to be extinct until they were rediscovered at Mount Hotham in the 1960s. Today, there are fewer than 2000 of the possums left in the wild.
The Mountain Pygmy-possum is Australia’s only hibernating marsupial and hibernates for up to seven months under the snow each year.
In 2020-2021, possum numbers significantly declined because of the lack of moths getting to the boulderfields. The number of Bogong Moths collapsed by an estimated 99.5% leading to the moths being added to the IUCN endangered species list in 2021. Surveys of Mountain Pygmy-possums across Victorian monitored populations showed that over 50% of females lost their young in the worst year.
Ms Perrin said light pollution along the eastern seaboard had also diminished moth numbers.
She said a concerted ‘Lights Off for Moths campaign’ was needed to ensure as many Bogong moths as possible reached the alps.
“The moths’ little navigation systems go skewif with the light pollution, so there’s attrition of moths all the way down the eastern seaboard, and only a certain proportion actually end up in the alps able to support the possums,” she said.
“We really need people to understand that these are indirect but critical impacts. Even though you may live far away from where a possum lives, it’s still a good idea to turn off any blaring lights in spring so the maximum number of moths can get into the Victorian boulderfields for these little possums. Their future really depends on it.”
Join 'Lights Off for Moths' to help save the Mountain Pygmy-possum
Zoos Victoria has been gathering data from citizen scientists about the whereabouts of the Bogong Moths since 2019. The Moth Tracker website asks members of the public to log sightings of Bogong Moths to help researchers track their migration patterns. For more information visit zoo.org.au/possum
Zoos Victoria Senior Conservation Biologist, Dr Marissa Parrott said “Everyone can be involved with Moth Tracker. If you think you’ve seen a Bogong moth, take a photo and upload it to the Moth Tracker website. Every sighting counts and you’ll be supporting both an amazing moth and a precious possum.”
For more information, take a look at Zoos Victoria's Bogong Moth explainer.
Page last updated: 24/10/23