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12.3 Training Northern Quolls to Avoid Eating Cane Toads 291

VetBooks.ir 12.3 Training Northern
Quolls (Dasyurus hallucatus) to
Avoid Eating Toxic Cane Toads

The introduction of invasive, feral species can
pose serious problems for native predators,
particularly if the invasive species is highly
toxic. If the invader possesses novel toxins to
which the predator species is evolutionary
naive, then predators that attack or consume
the invader can die from poisoning. A classic Figure 12.1 A female northern quoll, Dasyurus
example of this problem is the introduction of hallucatus, with one of her juvenile offspring that
cane toads (Rhinella marina) to Australia. were raised in captivity in a purpose built quoll
Cane toads are native to South America, and facility at the Territory Wildlife Park, near Darwin,
Northern Territory Australia. Source: Jonathan Webb.
were introduced to north‐eastern Australia in
the 1930s to control the grubs of the cane
beetle that were devastating sugar cane crops Australia. Quolls are particularly sensitive to
(Lever 2001). After multiple introductions, cane toad toxins, and die after mouthing large
the cane toads established viable populations, toads (Covacevich and Archer 1975; O’Donnell
and they then began spreading across the et al. 2010). Northern quolls are short lived,
continent, at an accelerating rate (Phillips and both sexes attain maturity at around
et al. 2006). Cane toads contain powerful 10 months of age. Males typically die after
toxins (bufodienolides) that are pharmaco- mating, and they seldom live longer than a
logically very different to the typical toxins year in savannah woodlands. Female survival
found in Australian native frogs (Daly and is also low, and many females do not live past
Witkop 1971). Australia has no native frogs or the age of two years (Oakwood 2000). These
toads in the genus Rhinella (toads native to unusual life history traits (short lived, with
Central and South America), and conse- male die off after mating) make this species
quently most native Australian predators lack especially vulnerable to extinction. As cane
physiological mechanisms for detoxifying toads spread across Australia’s Northern
toad toxins. Both adult and juvenile cane Territory, quoll populations crashed, local
toads look very similar to palatable native extinctions occurred, and the species was
frogs, and thus, many toad‐naive predators listed as endangered (Rankmore et al. 2008).
treat cane toads as prey, with disastrous and To protect quolls from extinction, researchers
fatal results. Large goannas, freshwater croco- collected quolls from the Darwin and Kakadu
diles, elapid snakes, and marsupial predators region, housed them at purpose built enclo-
can die after mouthing, attacking, or ingesting sures at the Territory Wildlife Park, and intro-
large toads (Covacevich and Archer 1975). duced them to two toad‐free islands. Quolls
The spread of cane toads across the top end flourished on these toad and predator‐free
of northern Australia has caused massive pop- islands, and the populations rapidly increased
ulation declines of large varanid lizards (Doody (Rankmore et al. 2008). Unfortunately, cane
et al. 2009), freshwater crocodiles (Letnic et al. toads are exceptionally good at rafting on
2008), and a marsupial predator, the northern floodwater debris, or hitch hiking in boots and
quoll (Dasyurus hallucatus) (Burnett 1997; camping gear, and they have colonised several
Woinarski et al. 2010). Quolls are spotted, car- islands, causing quoll populations to crash
nivorous marsupials (Figure 12.1) that are (Woinarski et al. 2011b). Thus, island quoll
roughly the size of a small domestic cat and populations are not necessarily secure from
they were once widespread across northern the threat of cane toads.