The cane toad, Rhinella marina, is a large, terrestrial amphibian recognized by its warty, dry skin and prominent parotoid glands behind its eyes. These glands produce a milky toxin that can be harmful to many animals if ingested. Averaging 10–15 cm in length, with some individuals reaching up to 24 cm, this species is native to parts of Central and South America. From its origins, the cane toad has spread globally, establishing populations across Oceania, the Caribbean, and Northern Australia.
Native Habitat: Origins and Characteristics
The natural range of the cane toad spans from the Rio Grande Valley in South Texas, through Central America, and into the Amazon basin and southeastern Peru. This vast area includes both tropical and semi-arid environments. Within these regions, cane toads inhabit diverse conditions including subtropical forests, grasslands, savannas, rainforest edges, coastal grasslands, sand dunes, and mangrove swamps.
In their native habitats, cane toads frequently occupy open areas and are often associated with seasonal Amazonian savannas and small freshwater lakes. Dense forest foliage tends to limit their dispersal, suggesting a preference for more open landscapes.
Invaded Habitats: Adaptability and Expansion
After being introduced outside their native range, primarily for agricultural pest control, cane toads have shown remarkable adaptability to new environments. This includes regions like Australia, various Pacific islands, and the Caribbean. This adaptability has contributed to their rapid and extensive spread.
Cane toads frequently colonize human-modified landscapes, such as agricultural fields, suburban gardens, urban areas, and disturbed natural habitats. They can be found in man-made ponds, drain pipes, under debris, and beneath houses. This adaptability to both natural and urban settings, even in drier regions where natural water sources are limited, has made them successful invasive species. For example, in Australia, their range has expanded significantly since their introduction in 1935, moving westward at an estimated 40 to 60 km per year.
Key Environmental Preferences
Cane toads exhibit specific environmental preferences. They require permanent water bodies for breeding, such as ponds, roadside ditches, or even backyard buckets, where females can lay thousands of eggs in gelatinous strings. Moisture and humidity are also important; they absorb water through their belly skin from damp surfaces rather than drinking.
For shelter from extreme temperatures and predators, cane toads seek refuge under rocks, logs, leaf litter, rubble, or garden debris during the day. While they are active mostly at night for foraging, they can remain active during dry seasons by seeking out moist refugia. Their diet is opportunistic, consisting primarily of terrestrial insects like grasshoppers, beetles, ants, and millipedes, but they will consume almost any animal they can swallow, including small vertebrates and even pet food.