How Big Can a Cane Toad Get? Toad Size Records and Giants

How big is a typical cane toad?

Frogs and toads are measured from the tip of the snout to the vent, the opening at the rear of the body, with the legs left out. By that measure, most adult cane toads are 10 to 15 cm (4 to 6 in) long, and the largest wild individuals reach about 24 cm (9.4 in). Stretched out with legs extended, a big toad looks far longer.

Females grow larger than males. Males are smaller, often more yellowish, with rougher, spinier skin and dark nuptial pads on their thumbs used to grip females during mating. A big female can be the size of a small dinner plate.

Most adults weigh a few hundred grams. Toads over 1 kg (2.2 lb) are uncommon, and those over 2 kg (4.4 lb) are genuinely rare.

Toadzilla: Australia’s giant toad

In January 2023, a ranger in Conway National Park, near Airlie Beach in north Queensland, spotted an enormous cane toad sitting on a forest track. Weighed later by park staff, the female came in at about 2.7 kg (6 lb), several times heavier than an ordinary adult toad, and was around 25 cm (10 in) long. Rangers nicknamed her Toadzilla.

Because cane toads are invasive in Australia, the animal was not released back into the wild. She was taken to the Queensland Museum so that scientists could study her. The weight was not measured under official record conditions, so it is described as an unofficial record, but it is one of the heaviest cane toads ever reported.

Prinsen: the long-standing record holder

For decades, Guinness World Records listed a pet cane toad from Sweden named Prinsen (“the Prince”) as the largest toad on record. Weighed in 1991, Prinsen reached 2.65 kg (5 lb 13 oz) and measured about 38 cm (15 in) from snout to vent when fully stretched out.

Record animals kept as pets need to be treated with caution, because captive animals with constant food can grow much larger and fatter than wild ones. Still, both Prinsen and Toadzilla show how big this species can become when conditions are right.

Why do invasive cane toads grow so big?

Several factors seem to help cane toads in invaded areas grow larger than toads in their native range:

• Fewer competitors at low density. Studies have found that cane toads tend to be bigger where their populations are less crowded. The largest toads are often found at the edges of an invasion, where toads have recently arrived and food is plentiful.
• Few enemies. Away from the Americas, toads escape many of the parasites and predators that kept them in check at home. Toads at the front of the Australian invasion, for example, have often outrun a lungworm parasite that infects older populations.
• Abundant food. In Australian towns and farms, toads gather under lights at night to feed on swarms of insects, and they also eat pet food, scraps and carrion.
• A long life. Cane toads can live 10 years or more and keep growing slowly throughout their lives, so the oldest individuals are usually the biggest.

The opposite also happens. On some Pacific islands, such as Fiji, cane toads tend to be smaller than in Australia, probably because of differences in food, climate and population density.

How does the cane toad compare with other toads and frogs?

The cane toad is generally regarded as the largest member of the true toad family, Bufonidae. Blomberg’s toad of Colombia and Ecuador can reach a similar snout-to-vent length but is much rarer. Other well-known toads are far smaller.

So while the cane toad is a giant among toads, the largest frog in the world, the goliath frog of Cameroon and Equatorial Guinea, is bigger still.

Does size make a toad more dangerous?

Bigger cane toads have larger parotoid glands and carry more toxin. That matters most to predators, because a big toad can deliver a lethal dose to a large lizard, snake or quoll. It is one reason why the arrival of cane toads in Australia has been so damaging; read more in why are cane toads a problem in Australia?.

For people, the size of a toad matters less than what they do with it. Toads should not be handled roughly or brought near the face, and anyone who may have swallowed toad toxin should seek emergency medical help immediately by calling 911 (US), 112 (EU) or 999 (UK).