Young Adult Cane Toad

Juvenile Cane Toad

Identification

The Cane Toad is the largest species in its family. Adult Cane Toads are usually heavy-built and weigh an average of up to 1.8kg. (4 lbs.). Their size may vary from 15-23 cm.(4-9 in.) and their skin is warty. The female is usually bigger and has softer skin than the males. Most juvenile Cane Toads when they first appear are about 10-15mm.(1 inch) long. Cane Toads will often blend in with its surrounding to hide itself from predators. Their back and sides may vary from olive-brown or reddish-brown, gray and yellow while their bellies are semi-yellow or semi-white with darker mottling. They have a round flat body, a prominent corneal crests, and light middorsal stripes. Their front feet are unwebbed while their back feet have leathery tough webbing. Cane Toads have short legs, a ridged bony head that extends forward from their eyes to their nose. Behind their ears are the parotid glands, which may cause their head to look swollen. These glands are used for defense against predators. The parotid gland produces milky toxic secretion or poison that is dangerous to all species. Some effects caused by its poison are burning of the eyes and hands, and skin irritation.
Young Cane Toads have a smooth dark skin with darker blotches and bars, and lack conspicuous parotoid glands. They can be distinguished from some native Florida frogs because they sit upright and are active in the daytime in dense clusters.
Cane Toad tadpoles are shiny black on top and have a plain dark belly and a short thin tail. They are smaller (less than 3.5 cm long) 1 3/8” than most native tadpoles and often gather in huge numbers in shallow water. Cane Toad spawn is unique in Florida. It is laid in long strings of transparent jelly enclosing double rows of black eggs. The spawn tangles in dense dark masses around water plants, and hangs in ropy strands if picked up.

Cane toads (Bufo marinus) are native to Central America and South America. In 1935 it was introduced to Australia from Hawaii. They also have been introduced to Florida, Caribbean Island, Venezuela, Puerto Rico and Philippines. The introduction of Cane Toads to many parts of the world was mainly to help control the population of insects that were threatening commercial sugar cane. The Cane Toads original habitat before its dispersal by humans was subtropical forests near fresh water. However, they can now be found in many places such as man made ponds, gardens, drain pipes, debris, under cement piles, and junk beneath houses. Cane Toads will usually stay on dry land; and reproduce in any shallow water near its surrounding.
Adult Cane Toads are active at night during the warm months of the year. During the day and in cold or dry weather they shelter in moist crevices and hollows, sometimes excavating depressions beneath logs, rocks and debris. They can survive the loss of up to 50% of their body water, and can survive temperatures ranging from 41º - 104ºF.
Cane Toads eat almost anything they can swallow, including pet food, carrion and household scraps, but most of their food is living insects. Beetles, honey bees, ants, winged termites, crickets and bugs are eaten in abundance. Marine snails, smaller toads and native frogs, small snakes, and small mammals are occasionally eaten by Cane Toads.
The tadpoles of Cane Toads eat algae and other aquatic plants which they rasp off with five rows of tiny peg-like teeth. They also filter organic matter from the water. Large tadpoles sometimes eat Cane Toad eggs.

Predators of Cane Toad tadpoles in Florida include dragonfly nymphs, water beetles, Saw-shelled Turtles and Keelback Snakes. Keelbacks also eat young toads; laboratory tests have shown that they can tolerate low levels of toad toxins. Young or adult Cane Toads are eaten by wolf spiders, freshwater crayfish, Alligators, crows, White-faced Heron, kites, Bush Stone-curlew, Tawny Frogmouth, Water Rat and the Giant White-tailed Rat. Some predators eat only the toad's tongue, or attack its belly and eat only the mildly poisonous internal organs.
Cane Toads can breed in most still or slow-flowing water, and tolerate salinity levels up to 15%. Male Cane Toads start calling for mates after the first summer storms or when water temperatures reach 77º F. The choruses peak in January and finish by March. The males congregate after dark around shallow water and mount females as they arrive at the water's edge. The male grips the female in the armpits (this is called axillary amplexus) and she releases her eggs, which are fertilized externally by the male's sperm.
Females lay 8,000 to 35,000 eggs at a time and may produce two clutches a year. The eggs hatch within 24-72 hours and the tadpole stage may last from three to twenty weeks, depending on food supply and water temperature - generally a range of 77º-86ºF is needed for healthy development. The tadpoles gradually change (metamorphose) into toadlets 3/8-1/2” in length that leave the water and congregate in large numbers.
Toads in the tropics grow very quickly and may reach sexual maturity within one year, but in temperate southern Florida they mature in 18 months to two years. An adult lifespan of at least five years has been recorded in wild Cane Toads; captive individuals have lived for up to 15 years. Only about 0.5% of Cane Toad individuals that hatch from eggs survive to reach sexual maturity and reproduce.

Cane Toads normally prey on insects and will eat any animal that they can ingest. Cane Toads eat almost anything such as small lizards, frogs, birds, fish, mice, bees, worms, dung beetles, scarab beetles and even younger Cane Toads. They are also known to steal food from dogs and cats if their food dishes that are left outside.

Status

Cane Toads are considered a pest in Florida because they:
• poison pets and injure humans with their toxins
• poison many native animals whose diet includes frogs, tadpoles and frogs' eggs
• eat large numbers of honey bees, creating a management problem for bee-keepers
• prey on native fauna
• compete for food with vertebrate insectivores such as small skinks
• may carry diseases that are can be transmitted to native frogs and fishes.
Cane Toads were introduced to Florida to eat French's Cane Beetle and the Greyback Cane Beetle. The 'whitegrub' larvae of these beetles eat the roots of sugar cane and kill or stunt the plants.
At that time, some naturalists and scientists warned of the dangers of liberating Cane Toads in Florida.

All stages of the Cane Toad's life-cycle are poisonous. The venom produced by the parotoid glands acts principally on the heart. No humans have died in Florida from Cane Toad poison but overseas, people have died after eating toads and even soup made from boiled toad eggs. Cane Toads are also poisonous to pets and in Hawaii up to 50 dogs a year have died after mouthing Cane Toads. Signs of poisoning through ingestion include profuse salivation, twitching, vomiting, shallow breathing, and collapse of the hind limbs. Death may occur by cardiac arrest within 15 minutes.
A Cane Toad responds to threat by turning side-on so its parotoid glands are directed towards the attacker. The venom usually oozes out of the glands, but toads can squirt a fine spray for a short distance if they are handled roughly. The venom is absorbed through mucous membranes such as eyes, mouth and nose, and in humans may cause intense pain, temporary blindness and inflammation.

First aid treatment includes irrigating (washing with a lot of water) the eyes, mouth and nose if they have been exposed to toad venom. Seek medical attention if symptoms persist. When handling any frog or toad, protect the eyes, wear gloves, and thoroughly wash hands before and after touching the animal.

The main controls on the spread of Cane Toads in Florida are quarantine checks and public awareness and response. Toads can be excluded from garden ponds and dams by a 19 ½” high barrier such as an thick hedge or a wire mesh fence.
If you think you have seen a Cane Toad, please catch it or report your sighting to a National Parks office or your state museum. It is important to confirm the identity before disposing of a suspected toad, because two-thirds of suspects turn out to be harmless native frogs (such as the Banjo Frog) that need our protection.