The Common Brushtail Possum is a nocturnal, tree-dwelling marsupial frequently seen throughout New Zealand’s forests and urban areas. With its thick fur and bushy tail, it can appear as a harmless native creature of the night. This animal, however, is not native to the country. It is an introduced species from neighboring Australia and is regarded as one of the most destructive pests in New Zealand’s history. Their widespread and dense population is a direct result of human action, leading to severe ecological and economic problems that persist to this day.
An Unwanted Introduction
Native to Australia, the Common Brushtail Possum (Trichosurus vulpecula) was first brought to New Zealand by European settlers in 1837 to establish a commercial fur trade. Subsequent introductions continued for decades, with acclimatisation societies releasing breeding populations into the wild until the practice was prohibited in 1921. Without the natural predators and resource competition that controlled their numbers in Australia, the possum population flourished in the lush forests of their new home.
By the 1980s, their numbers had exploded to an estimated peak of 60-70 million. It is important to distinguish this animal from the one found in the Americas. The New Zealand possum is a true possum of the suborder Phalangeriformes, whereas the North American opossum (Didelphis virginiana) belongs to a different order of marsupials. The American opossum has coarse fur, a pointed white face, and a bare, rat-like tail, while the Australian brushtail possum is known for its softer, thicker fur and bushy tail.
Ecological and Agricultural Damage
Each night, possums consume an estimated 21,000 tonnes of vegetation, targeting the leaves, flowers, and fruits of native trees. They show a preference for certain species, repeatedly stripping canopy trees like the northern and southern rātā, kāmahi, and tōtara. This intensive browsing can kill established trees, leading to the collapse of the forest canopy and altering the entire structure of these ancient forests.
Beyond the destruction of flora, possums are opportunistic omnivores. Initially thought to be herbivores, they are now known to be significant predators of native wildlife. Video surveillance has captured them raiding nests to eat the eggs and chicks of iconic birds such as the kiwi, kōkako, and kererū. They also consume invertebrates, including large native snails like the Powelliphanta, and compete directly with native birds and reptiles for food sources like nectar and fruit.
The damage extends from the forests to the farm. Possums are the primary wildlife vector for bovine tuberculosis (TB), a bacterial disease caused by Mycobacterium bovis. The disease poses a major threat to New Zealand’s dairy, beef, and deer farming industries. Infected possums can transmit the bacteria to livestock through close contact on pasture. This link has substantial economic consequences, costing the country millions annually in disease control and lost production.
Managing the Possum Population
A combination of methods is used to manage populations across vast and often rugged terrain. Ground-based strategies include trapping and the placement of bait stations containing poisons. These techniques are effective in more accessible areas and are often undertaken by government agencies, regional councils, and community groups.
For large-scale control in remote and difficult-to-access landscapes, the aerial application of biodegradable poison baits is a common method. The toxin sodium fluoroacetate, known as 1080, is used to reduce possum and other pest populations over thousands of hectares at a time. While the use of poisons is a subject of public debate, these operations are highly regulated to target pests effectively.
These control efforts are a component of New Zealand’s ambitious national conservation strategy. The “Predator Free 2050” initiative aims to eradicate the most damaging introduced predators, including possums, rats, and stoats, from the entire country by the year 2050.
The Possum Fur Industry
In a unique turn of events, the industry responsible for introducing the possum is now part of the solution. Today, harvesting possums for their fur provides a commercial incentive for trapping, directly contributing to conservation goals by reducing pest numbers. This has led to the marketing of the material as an “eco-fur,” supported by conservation organizations.
The physical properties of possum fur make it a highly desirable textile fiber. Each hair has a hollow core, a structure shared with polar bear fur, which makes it incredibly lightweight while providing exceptional insulation. Possum fur is often blended with merino wool to create a soft, warm, and durable fabric that is resistant to pilling.
The industry generates millions of dollars annually and supports jobs, turning a serious environmental threat into a valuable resource. By purchasing these products, consumers support the ongoing efforts to control possum populations and protect New Zealand’s vulnerable native wildlife and forests.