What’s common about a brushtail possum?

When you scroll through camera trap photos and see possum after possum staring back, it’s easy to understand why brushtails earned the label ‘common’. In Lutruwita/Tasmania, common brushtail possums are certainly doing well. Many veggie gardens and fruit trees will attest to that – and yes, it probably is a possum stripping the rind from your lemons. But Tasmania doesn’t tell the whole story.

Let’s take a closer look at our sometimes-maligned brushies – Trichosurus vulpecula, the ‘furry‑tailed little fox’ – and why common animals matter.

Common here, but not everywhere

Common brushtail possums are Australia’s most widely distributed marsupial, found across enormous spans of the continent, from the temperate south to the tropical north. But brushies have disappeared from large parts of their former range.

They are now mostly absent from arid zones and have declined across tropical and temperate woodlands in northern, south-western and eastern mainland Australia. One of the six subspecies, the northern brushtail possum (T. v. arnhemensis), is listed as Endangered in the Northern Territory and Vulnerable nationally and in Western Australia.

The causes are familiar: introduced predators, habitat loss, grazing pressure, altered fire regimes and climate change. In arid and semi-arid regions, their disappearance has closely tracked the spread of cats and foxes. Drought and extreme heat are likely to reduce their range even further.

Tasmania’s bigger, floofier brushies

Tasmanian brushtails are a bit different. Our possums are bigger, floofier, and often darker than their mainland relatives, though their coats can be blonde, silver-grey, rufous, chocolate-brown or black. Although not genetically distinct from south-eastern mainland populations, Tasmanian brushtails are still recognised as a subspecies because of their geographic isolation and distinctive appearance: T. v. fuliginosus, a name referring to their sooty (fuligo) colouration.

Tasmanian brushtails are especially committed leaf eaters. Leaves make up a bigger part of their diet than they do for mainland possums, with Eucalyptus and Acacia foliage accounting for 74–100% of their diet. They round this out with seeds, pollen, fruits, flowers and fungi. This variety helps them deal with the chemical toxins found in the plants they eat. They’ll also occasionally eat invertebrates, reptiles, birds or eggs.

Most brushtail possums weigh 1–4 kilograms and can live for up to 11 years. In Tasmania, births peak between April and June, although breeding can occur year-round. Young spend around five months in the pouch before hitching a ride on their mother’s back. Possums are generally solitary, with males ranging across the territories of several females. But females tend to call the shots, claiming the best dens for rearing young.

Hollows, drains and roof spaces

In Launceston’s CBD, tracked possums have been found using underground erosion tunnels and stormwater drains to move between feeding and denning sites. Most travelled 300–400 metres a night, although one possum went more than a kilometre to share a den with a female. Possums prefer hollows in trees and logs, but will readily use roofs, walls and underfloor spaces when tree hollows are scarce. To be useful, a hollow needs an entrance at least 5–10 cm wide.

A changing possum story

In Tasmania, brushtail possums are partially protected by law, but can still be taken under permit. They have long been valued for their fur and meat, including by Aboriginal people and later by European colonists. Today, they are still harvested in very large numbers under commercial and crop-protection permits.

Old bounty and royalty records give us some of the earliest clues about where possums were found in Tasmania and their number. But we know surprisingly little about how populations might have changed before the 1950s. In the excellent Nature of the Midlands book, one landholder recalled:

‘In the early days the men used to snare them and sell the skins, and it was all ringtail possum, and if they saw a brush possum they would talk about it for weeks and then for some reason or another, whatever it was, the population changed over amazingly quickly.’

Another remembered:

‘Once it was all ringtails and no brushies. In my youth when people spoke of a possum it was a ringtail they were referring to. I didn’t know what brush possums were until the early 1950s.’

This raises an interesting possibility. Perhaps Tasmania’s possum community has changed more than we realise. If only we had camera trap data back then!

Why common species matter

The brushtail possum is a good reminder that what feels common in one place may not be common everywhere. In Tasmania, brushies can feel impossible to avoid. On much of the mainland, the story is very different. There, brushtails have disappeared from large parts of their former range. But because the remaining populations are concentrated around towns, cities and other modified landscapes, many people still see them regularly. This can create the impression that the species is doing just fine, even as its distribution continues to shrink.

That is why common species should never be taken for granted. History is full of examples of once-abundant species that later crashed, sometimes before anyone realised there was a problem. There is worrying evidence that our most familiar species are declining fastest. Large studies of European and North American birds have found the steepest population declines among the most abundant and widespread birds. The common starling, for example, is now on the UK’s conservation Red List.

This matters because common species do much of the ecological heavy lifting. By virtue of their abundance, they contribute disproportionately to pollination, seed dispersal, nutrient cycling, pest control and many other ecosystem functions. When common species decline, the consequences can ripple through entire ecosystems.

Common species also help us understand how wildlife communities change through time. Sometimes a place may still have the same number of species, but different species are moving in, dropping out or becoming more common. This is known as species turnover, and Tasmania’s changing mix of ringtail and brushtail possums may be one example.

Common species provide an important benchmark for interpreting camera trap records, helping to put sightings of less frequently recorded species such as quolls and devils into context. That’s why we ask WildTracker participants to upload all camera trap records, not just those of threatened or unusual species.

Whether in forest, farmland or the roof of a shed, brushies are a steady presence in camera trap images. In Tasmania, their commonness is part of what makes them valuable; they are a familiar species, but also useful markers of change.

References

Carmelet‑Rescan, D., Morgan‑Richards, M., Pattabiraman, N. & Trewick, S.A. (2022), ‘Time‑calibrated phylogeny and ecological niche models indicate Pliocene aridification drove intraspecific diversification of brushtail possums in Australia’, Ecology and Evolution, 12(12), e9633. https://doi.org/10.1002/ece3.9633

Cruz, J., Sutherland, D.R., Martin, G.R. & Leung, L.K.-P. (2012), ‘Are smaller subspecies of common brushtail possums more omnivorous than larger ones?’, Ecological Research, 27(3), pp. 475–482. https://doi.org/10.1111/j.1442-9993.2011.02346.x

Gilfedder, L., Kirkpatrick, J., Wapstra, A. & Wapstra, H. (2002), The Nature of the Midlands, Midlands Bushweb, Longford, Tasmania.

Statham, M. & Statham, H.L. (1997), ‘Movements and habits of brushtail possums (Trichosurus vulpecula Kerr) in an urban area’, Wildlife Research, 24(6), pp. 715–726.

Banner photo by Glen Bain.