A line in the sand
Stretching 5,614 kilometers across three Australian states, the Dingo Fence is one of the longest structures on Earth. Construction began in the 1880s, originally to stop the spread of rabbits, but the fence was later heightened and fortified to protect valuable sheep flocks in southeastern Australia from the continent's top predator, the dingo (Canis dingo). This massive pest-exclusion barrier, made mostly of 180-centimeter-high wire mesh, inadvertently created a large-scale ecological experiment.
By dividing the landscape, the fence established two distinct zones: one "inside" (southeast) where dingoes are rare due to culling, and one "outside" (west and north) where they remain common. This sharp division allows scientists to directly compare the ecosystems and observe the effects of the removal of a top predator. The environmental changes are so clear that they are visible from space using satellite imagery, which shows differences in vegetation cover on either side of the barrier.
A series of consequences
The absence of dingoes inside the fence causes a trophic cascade—a chain reaction that moves through the food web. Without their primary predator, herbivore populations, especially kangaroos, have increased. One study counted 3,245 kangaroos inside a section of the fence where dingoes were rare, compared to only eight kangaroos in a similar area outside the fence where 85 dingoes were spotted.
This overabundance of kangaroos causes intense overgrazing, stripping the land of vegetation. The reduced plant cover has many consequences. Soil quality declines, with studies measuring lower levels of phosphorus, nitrogen, and carbon inside the fence. The bare ground becomes more susceptible to erosion, and the entire landscape can be reshaped as wind and sand movement patterns are altered.
The dingo's presence also limits smaller, invasive predators like red foxes (Vulpes vulpes) and feral cats (Felis catus). Where dingoes are absent, these mesopredators thrive, increasing pressure on smaller native animals. The result is that native biodiversity—from the dusky hopping mouse to small reptiles—is often higher on the side of the fence where the dingoes live.