Feral Animals and the Growing Threat to Australia’s Reptiles

Australia’s reptiles evolved in relative isolation, shaped by stable climates and complex ecological relationships. Over the past two centuries, however, that balance has been steadily disrupted. Habitat loss, climate change and pollution all play a role, but among the most immediate and persistent pressures on Australia’s reptiles are feral and introduced animals. These species alter ecosystems in ways that native reptiles are poorly equipped to withstand.

Climate Change as a Compounding Threat

Climate change underpins many modern conservation challenges. Rising temperatures, altered rainfall patterns and increased frequency of droughts and extreme weather events disproportionately affect reptiles, which rely on environmental conditions to regulate body temperature, breeding and activity cycles.

Many reptiles depend on local moisture regimes, particularly in riparian and wetland habitats. Climate-driven declines in amphibians — an important food source for many snakes — indirectly affect reptile populations. The spread of amphibian diseases such as chytrid fungus, combined with warming temperatures, has reduced prey availability for reptile predators, compounding the effects of habitat change.

Feral Cats: A Major Ecological Disruptor

Among terrestrial feral animals, cats pose one of the most significant threats to Australian reptiles. Feral and free-ranging domestic cats occur across nearly all habitats, from deserts and grasslands to forests and urban fringes.

While direct predation on snakes does occur, the greater impact comes from competition and ecosystem depletion. Cats kill enormous numbers of small mammals, reptiles and amphibians each year, drastically reducing the prey base that many reptiles rely on. Even species not directly targeted by cats are affected through reduced food availability.

Research suggests that feral cats kill tens of millions of reptiles annually across Australia. This pressure is continuous and widespread, particularly in fragmented landscapes where reptiles already face habitat loss.

Attempts to control feral cat populations are complex. Broad-scale culling can have unintended consequences, including rapid population rebounds as dominant individuals are removed and subordinate cats expand into vacated territories. Long-term solutions require coordinated, integrated management rather than single-method control programs.

Foxes and Rabbits: Indirect but Significant Impacts

Foxes and rabbits also contribute to reptile decline, often indirectly. Foxes compete with reptiles for prey and may occasionally prey on larger lizards and snakes. More significantly, foxes reduce populations of small mammals that form part of reptile diets.

Rabbits, while not major prey items for most reptiles, dramatically alter landscapes through overgrazing. Their impact on vegetation structure reduces shelter, basking sites and microhabitats essential for reptiles. Degraded ground cover also increases exposure to predators and extreme temperatures.

Cane Toads: A Unique and Toxic Threat

Few introduced species have had as dramatic an impact as the cane toad (Rhinella marina). Introduced in 1935 to control agricultural pests, cane toads now occupy vast areas of northern and eastern Australia.

All life stages of the cane toad are toxic. Native predators that attempt to consume them often die from poisoning, and reptiles are particularly vulnerable. Studies have documented fatalities in death adders, brown snakes, black snakes and tiger snakes following ingestion or even mouthing of cane toads.

Some reptile species appear more vulnerable than others. Snakes with large gape sizes, such as death adders and some taipans, are more likely to attempt to consume toads and receive a fatal dose of toxin. While some populations show signs of adaptation or behavioural avoidance over time, initial population crashes can be severe.

Complex Ecological Interactions

The impacts of feral animals rarely occur in isolation. Climate change, habitat fragmentation and invasive species interact in complex ways, making outcomes difficult to predict. In some regions, reptile populations have partially recovered after initial declines, while in others they remain depleted.

Emerging management strategies include habitat modification, restricting access to artificial water sources, and experimental behavioural conditioning to reduce predation on cane toads. These approaches show promise but require long-term investment and careful monitoring.

A Realistic Path Forward

Complete eradication of feral species such as cats and cane toads across mainland Australia is unrealistic. However, targeted, sustained management can reduce their impact. Success depends on integrated approaches that combine habitat protection, population control, public education and ongoing research.

Australia’s reptiles are resilient, but they evolved without the pressures now imposed by feral animals. Recognising and addressing these threats is essential if we are to maintain healthy reptile populations into the future.

Understanding the role of feral animals in reptile decline helps move the conversation beyond simplistic solutions and towards informed, practical conservation strategies that balance ecological realities with long-term outcomes.