Brushtail possum update
I suspect many readers were a little surprised and perhaps a little sceptical when they read the recent Brink column about brushtail possums. Since then, 40 hand-picked possums captured on Kangaroo Island by the Australian Wildlife Conservancy have been flown north to its 9,450ha Newhaven Wildlife Sanctuary, around 350km northwest of Alice Springs. The sanctuary is enclosed, free of cats and foxes and allows the possums to be monitored.
Australian pest species exports
It was also pointed out that the brushtail possum had been introduced to New Zealand, where it not only became a pest, but also did ecological damage. In Australia we have many introduced environmental pest species, but there are Australian species that have become problems after being introduced to other countries. Here is a list of some of them:
The coastal sheoak (Casaurina equisetifolia) has become an invasive species in the southern USA, South Africa and the Bahamas. It is also quite invasive in Australia where it will spread from roadside plantings.
Coast tea-tree (Leptospermum laevigatum) has become naturalised in parts of the USA but is sometime used to distil tea tree oil.
Broad-leaved paperbark (Melaleuca quinquenervia) has run riot in Florida, especially in the Everglades where it grows at the expense of native trees and clogs waterways.
Sweet pittisporum (P. undulata) now occupies 49% of the forested area of the Azores.
Red-necked wallabies (Notamacropus rufogriseus) are a traffic hazard in the Forest of Rambouillet, France (descended from escapees from a wildlife park).
Black swans have formed small breeding colonies in Europe where they compete with the local white swans.
The redback spider (Latrodectus hasseltii) has spread across much of Japan and is also in New Zealand.
The paper wasp (Polistes humilis) has also made its way to New Zealand.
Cottony cushion scale (Icerya purchase) is an Australian sap-sucking pest in California. Not to worry, the vedalia beetle (Rodolia cardinalis), another Australian species, keeps it in check.
There are any number of acacias and eucalypts that have found their way to other countries. Some of these become prolific pests. Regardless, they compete with the local indigenous species. It is interesting to spot eucalypts in the background of American TV shows and movies. Tasmanian blue gums (Eucalyptus globulus) were even introduced to Easter Island where the local tree, a palm tree, went extinct by about 1400 following the arrival of the Polynesians.
These examples are just some of the Australian species thriving in other countries. While we are quite aware of the many introduced species playing havoc with Australian ecosystems, we are less aware of the damage being done by Australian species once they become established overseas.
