Toads are amphibians that serve an important ecological role, primarily as sit-and-wait predators. While generally perceived as insectivores, their life cycle reveals a more complex answer to the question of whether they prey on their own kind.
Cannibalism Among Tadpoles and Adults
Cannibalism occurs across both life stages of a toad, but the behavior is far more pronounced in the larval stage. Toad tadpoles, especially those of species like the invasive Cane Toad, engage in feeding frenzies on eggs and newly hatched individuals of their own species. Studies on Cane Toads in Australia found that the tadpoles are 2.6 times more likely to consume their own hatchlings compared to their counterparts in the native range.
Cannibalism among adult toads is less common and highly opportunistic. Adult toads swallow anything that moves and fits into their wide mouths, including smaller frogs and other amphibians. If a smaller toad or juvenile triggers the adult’s feeding response, it may be consumed due to poor visual discrimination or hunger, making the act an accidental ingestion.
Why Toads Might Consume Their Own Species
The drivers for this behavior are rooted in resource management and survival, particularly in crowded or unstable environments. Cannibalism increases when population densities are high or when food resources become scarce, allowing survivors to gain a nutritional advantage and eliminate competitors. This improves the overall survival rate of the remaining population by reducing competition for limited resources.
The nutritional benefit from consuming a conspecific can be substantial, leading to faster growth and development. This is important for tadpoles in temporary pools, such as Spadefoot toads, which accelerate metamorphosis to exit the pond before it dries out. Research suggests that Cane Toad tadpoles are specifically attracted to the toxins present in their own eggs, which act as a chemical cue signaling a high-quality food source.
What Toads Normally Hunt
When not engaging in intraspecies predation, toads have a diet that changes between their aquatic and terrestrial life stages. Tadpoles are predominantly filter-feeders and herbivores, grazing on detritus, bacteria, plankton, and algae on submerged vegetation. They are also scavengers and will readily consume insect larvae and carrion.
Once they undergo metamorphosis, their diet shifts to a purely carnivorous one, focusing on a wide range of invertebrates. Adult toads are generalist predators, consuming large numbers of insects, including:
- Beetles
- Crickets
- Flies
- Insect larvae
They also frequently prey on soft-bodied invertebrates like slugs, snails, spiders, and earthworms, using their sticky tongue to capture prey before swallowing it whole.