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| Cane
Toads Bufo
marinus, Bufonidae
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| Habitat
and Distribution |

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Young
Adult Cane Toad |
Juvenile
Cane Toad |

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Cane Toads are found in habitats ranging from
sand dunes and coastal heath to the margins
of mangroves. They are most abundant in open
clearings in urban areas, and in grassland and
woodland.
The natural range of Cane Toads extends from
the southern United States to tropical South
America. They were deliberately introduced to
control scarab beetles that were pests of sugar
cane.
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Identification
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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.
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Habits,
Mating and Reproduction |
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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.
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| Tadpoles |
Hatching
spawn |
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.
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Diet |
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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
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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.
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Toxicity |
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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.
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First
Aid + |
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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. |
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Control |
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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.
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