When rabbits moved into the vast dune system that flanks South Australia’s Coorong in 1949, their population peaked at 26 rabbits per hectare and they never planned to leave.
A long-term study of vegetation cover on Younghusband Peninsula’s transgressive dunes by Flinders University SA researchers shows that rabbits were the most destructive factor affecting dune stability.
They were ahead of wind, temperature fluctuation and even rainfall – so reduction of the rabbit population was required.
Myxomatosis in 1952, then the rabbit flea in 1968, Rabbit Haemorrhagic Disease in 1995, and a combined virus in 2018.
With the final virus leading to a 40 per cent reduction on already low population numbers.
In one of the most long-term investigations into how rabbits can destabilise a natural, functioning ecosystem and compromised growth, aerial photographs of the peninsula from 1949 to 2017 show the damage clearly.
However, that vegetation cover has significantly increased in recent years, and stabilised the dunefields, since the rapid decrease of rabbit populations.
Historical records show that strong rains during spring accelerate vegetation growth in the Younghusband Peninsula dune system, but they also boosted rabbit populations and resulted in a critical reduction in vegetation coverage of the dunes.
Subsequent peaks in vegetative growth on the dunes through more than 65 years of records corresponds with the introduction of specific deadly viruses that dramatically reduced rabbit populations.
Findings from the study have significance for international concern about the protection of vulnerable land and shows the impact of introduced plants and pests into an ecosystem.
Rabbit population growth is often the trigger to vegetation destruction in vulnerable areas.