Beneficial Garden Critter or Exotic Pest?

Meet Mr. and Mrs. Giant Toad

The Giant Toad (a.k.a. Marine Toad or Cane Toad) is the largest of the Florida frogs and toads. When this non-native species is threatened, it secretes a highly toxic milky substance from its large parotid glands in the back of its head. This secretion will burn eyes, may inflame the skin, and can kill cats and dogs if they ingest it.

Originally released in sugar cane fields to help control rats and mice, it now is commonly found in South Florida yards. It breeds year round in standing water, streams, canals and ditches. The call is a low-pitched trill which sounds like an idling diesel engine.

Known scientifically as Bufo marinus, the Cane Toad, Giant Toad, or Marine Toad is native to an area extending from Mexico and Central America to the Amazon Basin.

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Florida’s first Giant Toad population was established in 1955 by an accidental release at Miami International Airport. Specimens imported by a pet dealer escaped and spread through canals to other areas. Pet dealers deliberately released the toad elsewhere in southeastern Florida in the early 1960s.

Bufo marinus can grow to 9 inches in length and more than 2 pounds in weight. Giant Toads prefer developed areas, where they use man-made canals and ponds for spawning and gather under electric lights to feed on insects. As the Giant Toads are too large and slow to flee predators, they defend themselves by secreting a milky toxin from glands located behind the head. Giant Toads can live for a least 15 years in captivity, and can breed for at least five years in the wild.

Identification

Giant Toads are heavily built, have short legs and no webs between their toes. Adults have a rough warty skin. Their color is tan, dull green or black, with a light underside. They have large glands behind the head which exude a poisonous milky substance when the toads are attacked.

The spawn consists of long double chains of black eggs enclosed in a transparent cover. They develop into tadpoles which form large, slow moving shoals.

Another sensational short film about Bufos from Australia — Cane Toad – What Happened to Baz? Will Floridians have the same problem (and attitude towards cane toads) in a few more years?

Food Habits

Giant Toads are omnivorous. They eat whatever is available. They will eat almost anything they can get a hold of — small amphibians, reptiles, birds, and mammals. In fact, they eat any animal they can swallow, and cat or dog food — unlike other amphibians, Giant Toads eat things which do not move so do not leave cat or dog food outside for your pets — the toads will sit in the bowls and eat it.

Bufo Marinus scat
Bufo Toad Scat

Reproduction

Giant Toads breed from June to January, but toads have been found in breeding condition throughout the year. Females produce 8,000 to 50,000 eggs in a clutch and can breed at least twice a year. Giant Toads normally lay eggs in slow moving freshwater streams, but they can also breed in brackish water. Tadpoles hatch in 48 to 72 hours. Depending on the water temperature and food availability, they can complete their development in 16 to 180 days.

Predators

Giant Toads produce poison from glands behind the head. The poison is highly toxic to most animals and produces pain and local inflammation if it contacts the eyes. Most predators are quickly killed after ingesting this substance.

Dogs and cats which bite Giant Toads die within a few hours. Native species of reptiles and mammals are also vulnerable. The eggs and tadpoles of Giant Toads are also poisonous.

Control

Biological control is probably the only practical means of limiting the spread or reducing the number of giant toads. However a recent study found little or no hope of such a control method. Giant toads are often transported in shipments of fruit and other commodities. Until effective control methods are available, quarantine checks and the destruction of any accidental releases of toads are essential to reduce their rate of spread.

The Choice is Up to You

Giant toads are beneficial for the gardener and homeowner in general. They have a huge appetite and eat millions of insects per year. They are poisonous, but only if carelessly handled — they do not attack humans or other large animals. They do displace native toads and reptiles and will eat other small mammals and birds if they can catch them.

Big Old Garden Toad Sculptures by Steve Worthington

Giant Toads can be removed and disposed of humanely (as recommended by the IFAS Animal Use Approval Committee) by placing them in a plastic container (or bag) in the freezer for three days and then burying the carcasses. If you do not wish to handle the toads, contact a local nuisance animal trapper. At FloridaGardener.com we believe that there seems to be no real need to make an active effort to control Giant Toads as they are more beneficial than harmful in the home yard and garden. However, if the population of toads grows out of control or you believe they may be a threat to your children, pets, or wildlife in your yard, then you may find it necessary to control the population in your yard.

 Sources: UF/IFAS News Release 2.08.01 Toxic Toads As Pets? UF Expert Says No Way

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