Tiny Trackers: Big moves for Australia’s small possum pollinators

A dozen Eastern Pygmy Possums are being relocated from two of Sydney’s national parks to North Head Sanctuary in Manly, where Australian Wildlife Conservancy (AWC) works in partnership with Sydney Harbour Federation Trust (Harbour Trust) to restore and protect locally extinct species. Three individuals were fitted with ‘tiny trackers’ aka one of the smallest collared radio transmitters available.

Throughout February, March and April, AWC and Harbour Trust set out to source up to 12 individuals from Ku-ring-gai Chase and Garigal National Parks. The translocation is part of an ongoing program to strengthen the native species’ population and protect the critically endangered Eastern Suburbs Banksia Scrub.

Each possum, weighing less than a golf ball at 45 grams, underwent health checks at the national parks before being placed into travel cases for a 45-minute drive to the nature refuge.

Brad Leue/AWC

During a translocation on 5 April 2023, Aiden Wright, AWC Field Ecologist, carefully removed an individual Eastern Pygmy Possum from the travel case and placed it into a pre-selected nest box. Before the release, the male possum, named after the Wallum Banksia, a characteristic species of the Eastern Suburbs Banksia Scrub, was provided with some supplementary feed until sunset, when he was able to emerge from his shelter. Once out and about, Wally will have explored his new environment and commenced the process of transferring pollen between flowers.

Executive Director of the Harbour Trust, Janet Carding welcomed the new individuals, saying that these little creatures play a significant role in protecting the critically endangered Eastern Suburbs Banksia Scrub.

Brad Leue/AWC

“As pollinators, Eastern Pygmy Possums perform the important task of moving pollen between the diverse Banksias on the headland,” Carding explained. “We are delighted to be working with AWC to strengthen the population of this species at North Head Sanctuary.”

“North Head’s delicate ecosystem is home to a rich diversity of flora and fauna, and its preservation is central to the Harbour Trust’s mission. Protecting these native species is so important.”

Brad Leue/AWC

Under this fresh round of reintroductions, a small selection of three tiny possums, including Wally, were fitted with ‘tiny trackers’ aka the M1410 series miniature mammal collars from Advanced Telemetry Systems Australia – this model is among the smallest collared transmitters currently available. Weighing under 1g and only 2cm wide, the lightweight collar enables tracking for more than one month once the individuals are released into the sanctuary. Ecologists will use the trackers to monitor the survivorship of the species and perform health checks during the important post-release period. The collars also allow the ecologists to track the animals to the exact locations where they are nesting during the day and help to paint a picture of how far the animals disperse post-release.

“Given the small size of Wally and North Head Sanctuary’s other new residents, they can often be difficult to locate once released into the wild,” explained Aiden Wright, AWC Field Ecologist. “Fitting them with collars equally as small will help us monitor them during that critical 3-4 week post-release period. The ability to track the animals post-release provides useful information in terms of their movement patterns and home range sizes.”

Brad Leue/AWC

Since the Eastern Pygmy Possum was reintroduced to North Head Sanctuary in 2016, the number of new individuals encountered during annual surveys has steadily increased – indicating that the population is growing.

In 2018, the team came across eight new possums born at North Head Sanctuary. In 2019, this increased to 19 new individuals and it continued to climb to 20 in 2020, 19 in 2021, and 49 in 2022, more than double the prior year.

Aiden Wright/AWC

Despite this strength in numbers, Aiden explained that the ongoing supplementation of the species from outside populations strengthens the sanctuary’s population.

“Supplementation of the species is vital for the establishment of the population at North Head Sanctuary,” Aiden added. “Adding new breeding adults to the population is vital for introducing new genetic diversity as the species continues to expand on the headland”.

Aiden Wright/AWC

Ecologists will follow up on the newly introduced individuals during a post-release survey in the coming months. Aiden expects they will have adapted to the new environment and commenced the process of adding new Eastern Pygmy Possums to the population.

Introduced predators, namely as cats and foxes, are a key threat to many native mammal species, like the Eastern Pygmy Possum. Recent government estimates suggest that across Australia, the yearly death toll from pet cats is more than 340 million native animals, with a single pet cat on average killing more 100 native animals per year when left free to roam. AWC regularly conducts monitoring for incursions of introduced predators on North Head Sanctuary and has, on occasion, recorded domestic cats accessing the headland.

Species Spotlight

Rhiannon Khoury/AWC

The Eastern Pygmy Possum is one of Australia’s smallest possums, weighing less than 45 grams and growing to just over 10 cm in length. It has a short snout, large round ears and grey-brown fur above with whitish underparts. It also has a long, sparsely-furred tail (also about 10 cm) which is able to wrap around twigs and branches, and is often used to transport new nesting materials into their nests.

A nocturnal species, the possum emerges at night to feed on nectar and pollen from flowering plants such as Banksias and eucalypts. It is an important pollinator, transferring pollen between flowers as it feeds.

The Eastern Pygmy Possum inhabits heathland, Banksia scrub and eucalypt forests along the south-east coast of Australia, from south-eastern Queensland to far south-eastern South Australia. Populations also occur west of the Great Dividing Range at Pilliga Forest in NSW, and in Tasmania.

For more information on AWC’s work with Harbour Trust at North Head Sanctuary, click here.