ENHS Nature Trails May 2003 Article 6

and Cane Toads in an Alien Land

Material selected from PamJam's website for educational and entertainment purposes only, and reflecting the opinions and style of Pam/Jam's readership. Edited for brevity. PamJam's website from Australia: http://www.geocities.com/westiez/dangers.htm

It's one of those "Don't we ever learn?" stories. It's Bufo marinus, More commonly known in Australia as the Cane Toad. A monster toad, almost big enough, ugly enough and nasty enough to play for any football team. Originally from Latin America, the cane toad can grow to more than seven inches and weigh more than three pounds. This amphibian has a face with big, puffy eyes and swollen glands running alongside each eye. It's these glands that make him nasty, since they hold a milky-white poison that is secreted when he feels threatened. We're talking about a poison with enough punch to kill a dog in just a few minutes, as many dog owners in Queensland have discovered.

So how did it get to Australia? We humans introduced it and now it can also be found in Hawaii, the Philippines, the Caribbean and the US. (Pet toad escaped at the Miami airport in 1855--now established in the South). In 1935 the cane toads were introduced to control cane beetles in north Queensland to eat the pests that plagued the sugarcane crop. Well that idea didn't quite work too well. It appears the toad decided it would not stay in the cane fields; it preferred to hop-off down the road in favour of richer meals, like dog and cat food that people leave out for their pets. Cane toads have spread at the rate of about 15 kilometers a year, and with no natural enemies in Australia * [Bufo marinus has some predators in Australia], they usually live about 20 years. A female cane toad can lay up to 40,000 eggs--most native frogs lay only about 1,000--and most native tadpoles can't live in the same water as the poisonous cane toad tadpoles. The offspring spread quickly and become major pests, killing dogs, cats and other inquisitive critters, both large and small. Cane toads have become so numerous in Queensland country areas that they often die in water holes, poisoning the water. They are carnivorous, poisonous, eco-thugs. Native animals that normally feed on native frogs try to eat the cane toad and die. Even grasping the toad in their mouths is enough to kill. Because the toads are multiplying so rapidly and because they will eat almost anything that will fit in their mouths, they are devastating the native ground dwelling micro-fauna. But worse, there is now evidence that cane toads carry a virus deadly to many native animals.

How to get rid of them! (With apologies to my Animal Rights friends) You can run over them with the car, hit them over the head, and shoot them, and they may appear dead, but often they are not. They have the ability to feign death, then a short time later, get up and hop away as if nothing has happened. However, they definitely don't do well in the cold and usually hibernate during winter. We have found that he most effective way to deal with them is to freeze them. Catch them, pop them in a freezer bag, seal it, then just make room in the family freezer and pop them in. Now, you need to be ready when you open the freezer to get something out for dinner. The frozen cane toad will immediately try to jump in your face; you've got to be ready to grab what you need and slam down the lid.

Additional Information summarized from the Australian Museum online: Bufo marinus, Cane Toad or Marine Toad, has a native habitat ranging from the Mexico to tropical South America. All stages of the Cane Toad's life-cycle are poisonous and the venom produced by the parotoid glands acts principally on the heart. No humans have died in Australia from Cane Toad poison but overseas, people have died after eating toads and even soup made from boiled toad eggs. 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. Australian native fauna that have been killed by eating or mouthing Cane Toads include goannas, Freshwater Crocodile, Tiger Snake, Red-bellied Black Snake, Death Adder, Dingo and Western Quoll.

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.

*Predators of Cane Toad tadpoles in Australia 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, Estuarine Crocodile, 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.

Editor's Note: Of course there were the usual paranoid naturalists and scientists who warned of the dangers of liberating Bufo marinus in Australia. The protestations of the introduction of cane toads were led by well respected members of the scientific community, a New South Wales Government entomologist, W W Froggatt and an Australian museum curator, Roy Kinghorn; their protests resulted in only a brief moratorium.

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