The Cane Toad (Rhinella marina, formerly Bufo marinus) is a large, heavy-bodied toad in the family Bufonidae. It is native to tropical and subtropical regions of Central and South America but has been widely introduced to other parts of the world, including Australia, many Pacific islands and the Caribbean, mainly in attempts to control agricultural pests. In many of these places it has become a notorious invasive species.
Taxonomy & Names
Common English names: Cane Toad, Giant Toad, Marine Toad
Scientific name: Rhinella marina (formerly Bufo marinus)
Family: Bufonidae (true toads)
Genus: Rhinella
Appearance
The Cane Toad is one of the world’s best-known large toads and is easy to recognise:
Body size: adults are commonly 10–15 cm in length, with large females sometimes exceeding 20 cm; body mass ranges from a few hundred grams to close to 1 kg in very large individuals;
Build: a broad, squat body with a wide, flat head and relatively short, strong limbs gives a very stocky appearance;
Skin: the back is dry, rough and covered with numerous warty bumps typical of many toads;
Colouration: dorsal colours are usually brown, yellow-brown, olive or grey-brown with darker blotches or mottling; the belly is much paler, often cream or greyish with faint spots;
Parotoid glands: behind the eyes is a pair of very large, elongated parotoid (poison) glands that can exude milky toxin when the toad is disturbed;
Sex differences: females tend to be larger; males have stronger forelimbs and develop dark nuptial pads during the breeding season.
Distribution & Habitat
In its native range the Cane Toad occurs in tropical and subtropical parts of the Americas:
from southern Mexico through Central America into the Amazon basin and parts of Brazil and neighbouring countries;
inhabiting lowland forests, savannas, river floodplains and wetland edges.
Through human introductions it is now found in:
many Caribbean and Pacific islands;
northern and eastern Australia, where it has expanded over vast areas;
some other tropical agricultural regions, especially those associated with sugarcane.
The Cane Toad is highly adaptable and uses a wide range of habitats:
croplands, sugarcane fields and grazing paddocks;
urban parks, lawns, gardens and roadsides;
ponds, ditches, dams and other still or slow-moving water bodies used for breeding.
Behaviour & Diet
Cane Toads are primarily nocturnal ground-dwellers:
by day they shelter in burrows, under logs, rocks, buildings or other shaded retreats;
at dusk and night they emerge to move slowly across the ground, often appearing on roads and lawns;
they are often temporarily “frozen” by bright lights, such as headlights or torches, which can make them easy to see and collect.
Their diet is very broad, and they are classic opportunistic feeders:
ground-dwelling insects such as beetles, ants, cockroaches, crickets and moths;
spiders, centipedes and other arthropods;
earthworms, small snails and sometimes small vertebrates such as frogs and lizards;
in urban areas they may also consume pet food and various scraps.
Toxins & Defence
The Cane Toad is famous for its potent toxins:
the parotoid glands and skin secrete a milky toxin containing bufotoxins and cardioactive compounds;
these can be deadly to many predators, including dogs, cats, some snakes, lizards and small mammals;
eggs and tadpoles are also toxic, so aquatic predators that eat them may be harmed.
Humans can experience irritation if the toxin contacts eyes, mouth or broken skin, and ingestion poses a risk of serious cardiac effects. In invaded regions, Cane Toads are responsible for many cases of poisoning in domestic pets.
Reproduction
Cane Toads are extremely fecund, contributing greatly to their success as invaders:
breeding typically occurs during wet seasons or following heavy rains;
females may lay several thousand to over ten thousand eggs at a time in long, gelatinous strings that are wrapped around vegetation or objects in the water;
tadpoles swim in groups and are usually dark in colour; their development rate depends on temperature and food supply;
once metamorphosis is complete, the tiny toadlets leave the water and begin life on land.
Invasive Impacts
In regions where they have been introduced, especially Australia, Cane Toads cause serious ecological problems:
their toxins kill native predators that attempt to eat them, such as large lizards, snakes and some mammals;
they compete with native frogs and toads for food and breeding sites;
they alter local food webs by consuming large numbers of invertebrates and by removing native predators through poisoning.
As a result, the Cane Toad is widely regarded as a harmful invasive species, and management efforts include public education, control of breeding sites and removal programs.
Conservation Status
Globally, the Cane Toad is listed as Least Concern (LC) on the IUCN Red List, reflecting its huge and expanding populations. This status reflects its success and widespread distribution rather than any need for protection.
In native range countries it is simply part of the local fauna, whereas in many introduced regions the priority is to limit its spread and reduce its impacts on native ecosystems.
