Cane Toad What is a Bufo Toad?
The cane toad is the world’s largest toad. It has dry, warty skin and highly poisonous glands on its shoulders. It is typically 10–15 cm in length and weighs about 1.4kg. The cane toad is native to South and Central America and southern Texas, USA.
The cane toad was introduced to Australia in 1935 to control native beetles that were attacking sugarcane crops. Unfortunately, these imported cane toads indiscriminately ate all insects and small native animals. Having no significant native predators, the cane toad population has multiplied from a mere 102 animals imported in 1935 to over 200 million in Australia today. Today the cane toad is also found in many other parts of the world.
The cane toad is also called a Bufo Toad, Marine Toad and Giant Toad. Its current scientific name is Rhinella marina. Its previous scientific name was Bufo marinus.
Cane Toad Description What Does a Cane Toad Look Like?
Cane toads are grey, yellowish, red-brown, or olive-brown in colour with rough, dry, blotchy skin with varying patterns and covered in warts. The underside of their bodies is smooth and creamy in colour with grey mottling. Male cane toads are smaller than females and have more warts. Cane toads live for 5-10 years.
Cane toads have distinctive bony ridges on either side of their heads that run from their snouts, over their eyes and terminate at a prominent poisonous paratoid gland behind each eardrum. It has horizontally shaped pupils with iris-surrounds edged in a golden coloured. Their hind feet are slightly webbed at the base, but the fingers are free of webbing. They sit upright and move in short, rapid hops.
The cane toad sounds like a tractor in the distance or a screeching owl. Its call is a slow, low-pitched trill with each note clearly distinguishable from the next.
Cane Toad Poison Can Cane Toad Kill A Human?
A cane toad is poisonous during all stages of its life cycle: eggs, tadpoles, juvenile and adult toads are all poisonous.
The adult cane toad has two large poison parotoid glands on its shoulders (see photo). Located just behind its eardrums, these glands produce a milky alkaloid known as bufotoxins; a neurotoxin intended to deter predators. This poison can cause rapid heartbeat, excessive salivation, convulsions, and paralysis resulting in death when ingested.
Cane toads have also been known to squirt their poison when threatened. If the poison gets into your eyes, it can cause severe eye damage and even blindness. Skin contact can be very hazardous too.
Theoretically, a cane toad's poison can kill a human. Several people overseas have died from eating them. No humans have been killed by a cane toad in Australia. However, many dogs have eaten cane toads and died.
Cane Toad Habitat & Distribution Where to Cane Toads Live?
Cane toads are native to South and Central America. They were subsequently distributed by humans to many other parts of the world were sugarcane was cultivated. These include Hawaii, the Philippines and Australia in the pacific region.
Typically cane toads live in grasslands, open forests, swamps, pastureland, farmland and suburban areas.
Video: Diagram of cane toad migration
Since their introduction to Queensland, Australia, in 1935, cane toads have expanded their range across Queensland, the Northern Territory, northern New South Wales and even Western Australia. They are estimated to be moving westward across the Australian continent at a rate of 40 to 60 km per year.
Cane toads are extraordinarily hardy and adaptable animals. Historically cane toads lived in reasonably moist environments and were strictly nocturnal, coming out to hunt only at night. However, Australian scientists have discovered that cane toads have changed their behaviour as they moved further into the semi-arid interior of the Australian Outback. While the cane toad has a high tolerance to water loss, some can withstand a 53% loss of body water; they cannot survive for more than a few days without water. They have tackled this environmental hurdle by hiding crevices and under logs and debris during the heat of the day and congregating around man-made dams and watering holes intended for water cattle and sheep flocks. By staying cool and rehydrating themselves against the extreme daytime heat, they have found a way to survive the hot and dry environments of the Australian Outback.
Cane Toad Diet What Do Cane Toads Eat?
Cane toads eat invertebrates, small rodents, reptiles, other amphibians, and birds. They also eat various plant matter, dog food, and household refuse. In fact, cane toads will eat any animal or plant—dead or alive that will fit into their large mouths.
Cane toads identify their food by sight. To a lesser extent, they can also identify a meal by smell. Cane toads don’t drink water; they use their bellies to absorb it from dew, moist sand, and other material in their environment.
Cane toad tadpoles eat algae and aquatic plants, which they rasp off with five rows of tiny peg-like teeth. They also filter organic matter from the water.
Cane Toad Reproduction & Life Cycle Cane Toad Eggs, Babies, Tadpole
Cane Toads breed twice a year in still or slow-flowing water. During the breeding season, male cane toads develop dark lumps (nuptial pads) on their first two fingers, which help them cling to a female while mating. Their mating call is a long, loud purring trill, similar to the sound of a small engine running.
The female lays long, transparent, gelatinous strings with double rows embedded black eggs. A female can lay between 8,000-35,000 eggs at a time. These strings sink and tangle in dense dark masses around water plants. Cane toad eggs hatch within 24–72 hours of the eggs being layed.
Cane toad tadpoles are small, oval in shape, and usually black in colour with dark bluish grey or black bellies. They grow to around 10-25mm, have short rounded tails and transparent fins. Cane toad tadpoles tend to cluster in slow-moving groups and do not come to the surface to breathe like native frog tadpoles.
The juvenile cane toads (toadlets) are between 1–1.5 cm when they leave the water. They have smoother, darker skin with darker blotches and bars than their adult counterparts and the lack of conspicuous parotoid glands of the adults. They frequently cluster in large numbers near water and are active during the day.
Mortality is high for the young toads, but those that survive grow quickly and reach sexual maturity within a year. An adult cane toad has no natural native predators in Australia and lives for 5-10 years.
Why was the Cane Toad Introduced to Australia? How the Cane Toad Arrived in Australia
A native of South and Central America, the cane toad was brought to Australia in 1935 to control native beetles that were attacking sugarcane crops. Starting in the 1860s, sugarcane became a major agricultural crop in Queensland. However, farmers were having a major problem with the larvae of native beetles (collectively referred to as cane beetles) eating the roots of the cane and killing and stunting the plants. These native beetle grubs had proven to be resistant to conventional methods of pest control available at that time. (This was a time before the widespread use of agricultural chemicals.)
In 1935, news reached Australia that a large toad from central American had solved a similar problem in the sugarcane fields of Hawaii, the Philippines and Puerto Rico. In June 1935, a government entomologist named Reginald Mungomery working for the Queensland Bureau of Sugar Experiment Stations (BSES) travelled to Hawaii and returned with a captured breading sample of toads. These animals quickly produced a captive population. Without a proper assessment of the potential benefits and dangers posed by these animals, 2400 were released Gordonvale near Cairns, Queensland, in 1935, to hunt and kill the cane-destroying native cane beetles.
Walter Froggatt, another entomologist, was concerned and wrote 'this great toad, immune from enemies, omnivorous in its habits, and breeding all year round, may become as great a pest as the rabbit or cactuses." He lobbied the federal government, and in December 1935 the further release of the toads was banned. However, the BSES and local cane growers urged the Queensland government who in turn pressured Prime Minister Joseph Lyons and had the ban rescinded in September 1936. Toads were then released throughout the sugarcane regions of Queensland.
Cane Toads proved to be a spectacular failure in controlling cane beetles. Instead, they wreaked havoc on native wildlife.
Cane Toad Environmental Impacts Why are Cane Toads a Problem?
Cane toads have no natural enemies in Australia. The main reason for their threat status is because they are poisonous, adaptive, predatory, and competitive. Cane toads don’t have any noticeable economic impact in Australia as they don’t affect agriculture and animal husbandry, etc. They do pose a nuisance factor, however, because of their presence in urban areas.
Their key impacts are to native fauna, where the cane toad’s detrimental impact on one or more species may have a cascading effect up and down the food chain. Cane toads are poisonous at all stages of their lives, and their toxins can kill most native predators that eat them. Hence the northern quoll (now extinct mainly due to cane toads), snakes, birds, etc., are susceptible to death caused by ingesting a cane toad.
Cane toads are robust and can quickly adapt to new environments as proven by their migration into more and more arid areas of the interior of Australia, which is far removed from their historically moist environments. They also breed rapidly, quickly dominating their new environments and displacing native species.
Being the largest toad in the world, the cane toad has a voracious appetite and will consume any animal that it can swallow. This has a devastating effect on native animals and ground-dwelling micro-fauna (small ground creatures) in areas they invade. These may include native frogs, smaller toads, small mammals and snakes.
Cane toads compete with native species for both food and habitats. Their generalist characteristic allows them to eat a wide variety of food, depriving native animals with less varied diets of sustenance. In large numbers, they displace other amphibians from their habitats.
Cane Toad Predators & Threats What Eats Cane Toads?
The cane toad has few natural predators in Australia. Over time, a few native animals have found ways of avoiding the cane toad's deadly poison and making a meal of them.
One of the most interesting killers of cane toads is the Australian crow. This bird has figured out that by flipping the cane toad on its back, it can avoid the toad’s poison glands. The crow then pecks through the toad’s mouth and soft underbelly and eats its insides.
The rakali or native water rat also flips the cane toad over, slices open its abdomen with its shape incisor teeth and removes and eats the cane toad’s heart and liver only. Spiders such as the common wolf spider and Australian tarantula can also kill and eat cane toads. Meat ants and water beetles eat millions of young cane toads and tadpoles each year.
Cane Toad Conservation Status Is the Cane Toad Endangered?
With over 200 million cane toads in Australia today, the cane toad is an invasive pest. It is not endangered and not protected by any legislation.
Cane Toad Eradication How to Get Rid of Cane Toads?
To date, no effective eradication strategy for these invasive pests exists. Trapping has been attempted, but it has found to be ineffective because native species are also caught in these traps. Furthermore, removing these trapped toads only improves the conditions for those remaining.
Viral, bacterial and poisoning agents have been examined, but these have been considered too dangerous, as they may also impact native species.
25 Cane Toad Facts
- The cane toad is the world's largest toad. Its size is 10-14cm long and weighs about 1.4kg.
- Cane toads have two large poison glands on their shoulders that ooze and squirt poison.
- They are poisonous their entire lives, from eggs to adults.
- The cane toad is native to Central and South America.
- A few cane toads were brought to Australia in 1935 to control native sugarcane beetles.
- The imported cane toads didn't do the job.
- Instead, they multiplied exponentially and indiscriminately ate other insects and small native animals.
- There are about 200 million cane toads in Australia today.
- No humans have been killed by a cane toad in Australia. That's because no one has tried to eat one.
- But overseas, people have died from eating them.
- Cane toads don't have any natural predators in Australia.
- Over time a few native animals have found ways of avoiding the cane toad's poison and successfully kill and eat the non-poisonous parts of the cane toad.
- Cane toads don’t cause any noticeable economic impact.
- However, they have a significant impact on native animals that have no immunity to the toad's poison.
- Cane toads will eat anything dead or alive that will fit into their mouths.
- But they don’t drink water. They absorb it through their skin instead.
- They can tolerate high temperatures and the lose of to up to 53% of their body weight and still survive.
- Their mating call sounds like a small engine running.
- A female cane toad can lay 30,000 eggs a year, but only about 5% survive to adulthood.
- They are feral pests resulting in the death of numerous native animals.
- While they can handle harsh dry conditions, they require water to lay their eggs in.
- The largest cane toad captured in Australia weighed 2.6kg and was 36cm long.
- Walter Froggatt, an entomologist, warned against importing cane toads, but no one listened.
- There isn't an effective means of eradicating these invasive pests.
- Cane toads live for 5-10 years.
All Rights Reserved. (Last Updated: Feb 18, 2022)