MARCH: WESTERN SHIELD PROJECT

Globally unique and one of the largest threat abatement programs in the world, the Western Shield program aims to halt the decline of Western Australia’s native fauna. Such is the task of zoologist Dr Michelle Drew from the Department of Biodiversity, Conservation and Attractions (DBCA) who spoke to DRB in March. Michelle’s specific job is to understand if current management is effective at maintaining populations of native mammals throughout their range in the South West.

Michelle reminded us of the vital importance of Western Shield:

• Australia has the most diverse fauna of any developed country in the world and is currently ranked in the top 17 of mega-diverse countries.
• Yet we continue to lose species—one fifth of all mammal extinctions world-wide since 1600 have occurred in Australia
• Since European settlement, 30 native mammals have become extinct.
• 1 out of every 3 mammal extinctions in the last 400 years have occurred in Australia (North America has lost only one mammal species since European settlement.)
• 56 of our endemic mammals are threatened with extinction, 52 near threatened, and 7 species now only exist on islands.

Why did this happen to so many widespread (Australia-wide), successful and ecologically flexible species? It is all about size. In Australia if you are a mammal you are in dire straits if you are small and weigh between 35g and 5.5kg. This is called the Critical Weight Range (CWR). In other parts of the world extinction typically affects larger mammals (e.g. rhinos, tigers, wolf). So why in Australia have we lost these smaller animals?

Much research has gone into attempting to understand these losses. While threats including changes in fire regimes and loss of habitat can be causal, recent assessment of the causes for declines in Australian mammal species has now indicated that up to 155 species of native mammals have gone extinct or are threatened with extinction because of foxes and cats (Woinarski et al 2015).

So baiting began—and let it continue…

Originally known as “Operation Foxglove”, then rebadged “Western Shield” in 1996, the Western Shield program exploits something uniquely Western Australian: an anti-herbivore metabolite or toxin called monofluroacetate, regularly known as 1080. Fluoroacetatic acid is an organofluorine toxin that is naturally produced in some plant species (also found in some plant species in Brazil and South Africa). Sodium monofluroacetate was first developed in a laboratory in the 1890s as a preservative to protect clothing against moths. Its naturally occurring form (potassium fluroacetate) was identified in plants around the 1940s. Lab trials to refine the formula resulted in its more common name of 1080.

Native fauna in WA have evolved alongside plants with this toxin and have therefore developed a strong tolerance to it. Confined to the southwest of the state (39 of the 40 known toxic plant species occurring here) means 1080 can be used very effectively here in WA with minimal non-target impacts. As such, the Department of Conservation and Land Management (CALM, now DBCA) developed bait loaded with 1080 that effectively culls foxes with minimal impact to native fauna. It is a dried salami-like product that is either aerially delivered or in some areas delivered via vehicle.

So successful has Western Shield been, the program has expanded from the initial 700,000 hectares (of northern Jarrah forest and the Wheatbelt) in 1996 to now cover 3.8 million ha between Esperance and Karratha. The early recovery of animals across the state was startling. Of the four main species monitored, the Woylie (Brush-tailed Bettong); Chuditch (Quoll), Quenda (Southern Brown Bandicoot), and the Brushtail Possum, recovered well. The Woylie was even removed from the threatened species list.

However, in the early 2000s the situation changed and many of the species that had started to recover began to decline. Research indicated that feral cats were now the primary issue. The fox numbers declined and the cat stepped in.

Western Shield is now challenged to manage cats as well as foxes. The biggest difficulty is how to monitor these predators effectively. Within the 36 Western Shield monitoring sites across the State (the Perth Hills sites are located in Julimar, Bindoon and Hills Forest); a new control program is being established in four primary test areas in the south and a few independent programs in its northern areas. Predators are hard to monitor due to their reticent and trap-shy behaviour. The newer technology of automated wildlife cameras is providing insight into animal behaviour. Ninety cameras are now in use within the northern Jarrah forest as well as a number of locations on the Swan Coastal Plain, southern Jarrah forest, Midwest and the south coast. All these cameras generate a lot of data. Michelle indicated when she first started with Western Shield she had 500,000 images to sort… gulp!

Fortunately for Michelle, technology and citizen science have come to her aid. In collaboration with a web-based organisation called Zooniverse, Michelle built the ‘Western Shield camera-watch’ monitoring project. Citizen scientists or registered volunteers join the project and assist with the interpretation of the data. There has even been a primary school class in Poland contributing to the project!

The project is called: ‘Western Shield camera-watch: Discover the night life of the Jarrah forest of Western Australia’

A new batch (2017) images are currently being loaded into the project. Michelle encourages us to become part of this successful Western Australian program by assisting with the sorting of images. She assures us you will be hooked once you start! This project now enables all of us to contribute to getting rid of cats and foxes in order to future proof the ‘most diverse fauna of any developed country in the world.’

Diana Papenfus