A study commissioned by the North East Catchment Management Authority (CMA) has found the threatened Mountain Pygmy-possum consumes a wide variety of plants and insects during its breeding season and its diet is not confined to the Bogong moth.
The study found the Bogong moth continues to be a key dietary item for the possum during its breeding season and in the rearing of its pouch young. It aimed to determine how important the moths and other food sources are to the possum’s diet throughout the remainder of the year.
The study found the diversity of the possum’s diet may be linked to the biodiversity of their surrounding habitat, that is, the number of species of plants and insects in the environment surrounding their homes.
North East CMA project officer Phill Falcke said the study had been commissioned through the Cesar Laboratories in Melbourne to find out what the Mountain Pygmy-possum is eating, and what proportion of their diet consists of Bogong moths, particularly when moth numbers are known to have been in decline.
“Pouch Young Litter Loss (PYLL) is a phenomenon observed where Mountain Pygmy-possum females in a local population have lost their pouch young,” Mr Falcke said.
“This phenomenon was observed in bushfire-affected sites in 2004-06 and again between 2017 and 2019.
“Monitoring during January and February this year found almost all the female possums were in fair to good condition and there was limited evidence of Pouch Young Litter Loss.
“The cause of Pouch Young Litter Loss is not well known, but it’s suspected that it may be caused by the decline in Bogong moth numbers over the past decade.”
There are only about 2000 Mountain Pygmy-possums left in the wild, and their population is confined to three small regions across alpine and sub-alpine southern Australia, including north east Victoria.
Monitoring of the possums during 2021 yielded about 70 per cent of the numbers usually observed in a season.
Mr Falcke said the study represented a new approach to understanding the diet of the possums. Possum poo or scats, collected during the annual monitoring of the animals, are analysed using environment DNA (eDNA) metabarcoding.
The method is able to determine the diet of individuals at different sites and on different occasions during their breeding season between spring and summer, including different types of plants and insects.
“The study indicated that the Bogong moth remains an important food source for the possum; with 78% of scats sampled containing the moth,” Mr Falcke said.
“The study highlights that a reference DNA sample library of plants and insects surrounding Mountain Pygmy-possum habitat locations needs to be compiled so DNA analysis of the possums’ diet can more easily and accurately be gauged against the diversity of their surrounding habitats.
“Long term diet research across seasons and locations is also needed, and this will give a more accurate picture of what the possum’s future is and what we need to do to halt further decline.”
This month has seen the launch of Moth Tracker for 2021. If you think you see a Bogong moth, snap a photo and upload it to Zoo Victoria’s Moth Tracker website. Photos uploaded to Moth Tracker help provide scientists with important information about the annual Bogong moth migration and give an early indication of what the season may bring for Mountain Pygmy-possums.
The study was undertaken through funding from the Australian Government’s Australian Heritage Grants Program. The Mountain Pygmy-possum Recovery Project is supported by the North East CMA, Parks Victoria, Mount Hotham Alpine Resort Management Board, Falls Creek Alpine Resort Management Board, DELWP and Zoos Victoria, through funding from the Australian Government’s National Landcare Program.