about the cane toad
why is it exotic?
- Native range in Central/South America
- Intentionally introduced to Hawaii in order to benefit the sugar cane industry (successful: introduced to control scarab beetles)
- Intentionally introduced to Puerto Rico to benefit the sugar cane industry (successful: introduced to control white grub infestation; years of heavy rainfall also helped)
- Intentionally introduced to Australia to benefit the sugar cane industry (unsuccessful: introduced to control cane beetles)
invasion - introduction to Australia
- Cane Toads initially invaded northeastern Australia in 1935 -- 102 toads
- The Cane Toad has spread throughout the northeast and westward ever since
- The Cane Toad has also spread along the coasts
- The Cane Toad's rate of expansion in Australia is 25 miles per year
- Currently Cane toads inhabit 1.2 million square kilometers of Australia
- Future range area of Cane Toads in Australia is expected to exceed 2.0 million square kilometers (that's larger than the area of Alaska)
- There are currently over 1.5 billion Cane Toads in Australia, with that number increasing every year
- Gray map (left) = current range
- Black map (right) = projected range
- Introduced to Australia to control cane beetle infestation, but Cane Toads were ineffective as bio-control agents and conditions allowed for an expanding range
- No natural predators
- No natural pathogens/parasites
- Favorable and fast life history traits (see "Life History" below)
ABIOTIC FACTORS THAT AFFECT SPREAD:
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BIOTIC FACTORS THAT AFFECT SPREAD:
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life history
HABITAT: Temperate, and tropical regions (e.g. South America, Northern Australia)
FECUNDITY: 30,000 eggs per female per spawning event
REPRODUCTION: Spawning events occur 2x per year
PLENTIFUL AVAILABLE RESOURCES: Opportunistic feeders--can eat anything that fits in their mouths
High reproductive rates, high fecundity (# of offspring per female), fast life history, and large amounts of available food makes the Cane Toad a successful invasive species
FECUNDITY: 30,000 eggs per female per spawning event
REPRODUCTION: Spawning events occur 2x per year
PLENTIFUL AVAILABLE RESOURCES: Opportunistic feeders--can eat anything that fits in their mouths
- Eat mostly insects such as beetles, bees, ants, termites and crickets
- Marine snails
- Small mammals
- Smaller toads and native frogs
- Small snakes
- Cane Toad tadpoles eat algae and other aquatic organisms
High reproductive rates, high fecundity (# of offspring per female), fast life history, and large amounts of available food makes the Cane Toad a successful invasive species
impacts
IMPACTS ON NATIVE SPECIES: Competition and Predation
Cane Toads produce a highly toxic poison that they secrete from skin glands when threatened. The Cane Toad invasion has led to declines in native mammalian and anuran (frog/toad) populations due to competition, predation, and toxicity of the invasive Cane Toad, as well as declines in top-level predators, such as fresh-water crocodiles, that are killed when they eat toxic Cane Toads. Since their introduction into Australia, the above impacts have been felt on native Australian organisms.
http://www.environment.gov.au/node/14576
- Generalistic feeding habits. They are opportunistic feeders!
- They are toxic at all stages of their life cycle
- Ability to out-compete native frogs for food and habitat
- Potential for spread of disease to native amphibians
Cane Toads produce a highly toxic poison that they secrete from skin glands when threatened. The Cane Toad invasion has led to declines in native mammalian and anuran (frog/toad) populations due to competition, predation, and toxicity of the invasive Cane Toad, as well as declines in top-level predators, such as fresh-water crocodiles, that are killed when they eat toxic Cane Toads. Since their introduction into Australia, the above impacts have been felt on native Australian organisms.
http://www.environment.gov.au/node/14576
IMPACTS ON HUMANS:
Cane Toads can also impact the humans that disturb them. They can:
Cane Toads can also impact the humans that disturb them. They can:
- Secrete toxins (from parotoid glands) that can cause human children and pets to become sick or even die
- Out-compete native species that are utilized by humans as food sources
- Can cover backyards and gardens with a carpet of frogs, causing a nuisance