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Cane Toads Found on Sanibel


As of July 29, the cane toads have been confirmed at 8 locations and possibly 1 more.


Story on WGCU web site, July 22, 2013

Background

On Wednesday, July 17, during monthly frog call surveys conducted by the J.N. “Ding” Darling National Wildlife Refuge (Refuge) and the Sanibel-Captiva Conservation Foundation (SCCF) on Sanibel, a population of giant toads (Rhinella marina {= marinus]), also known as cane toads or marine toads, were discoveredcane toad breeding in a temporary wetland near Middle Gulf Drive and Fulgar Street.

This species poses a SERIOUS threat to wildlife on Sanibel, as well as domestic pets. The large glands behind the eyes and above the shoulders (parotoid glands) produce a toxin (bufotoxin) that is both irritating and deadly to smaller wildlife. When a predator grabs a giant toad in their mouth, the toad inflates its body and the toxin oozes out of the parotoid glands into the mouth of the predator. It is well documented that the poison has killed pet dogs in south Florida. The literature and conversations with veterinarians and pet owners indicate it is a horrific death for the animal. There have even been human fatalities from this species from toad-licking. The tadpoles are also toxic, which can lead to fatalities in many animals that consume them. Special care should be taken to prevent dogs, cats, etc from biting or grasping these toads in their mouths.

These are very large toads, reaching up to 5.5 inches in length and possibly near five pounds. They are voracious eaters. They will eat insects, snakes, baby turtles (including small sea turtles, gopher tortoises, box turtles, etc), lizards, small mammals, and birds. They will even eat pet food or any other kind of food left outside. It is highly unique for a frog to eat nonliving food. These toads are attracted to bright lights at night because they attract insects.


Southern toads are also true toads that are native to Sanibel, but they are smaller than cane toads and the parotoid glands (one is found on either side of the head) are smaller in southern toads.  Southern toads also have "toxin" (more of an irritant) in their parotoid glands that make them unpleasant to many native species. However, there are native species that specialize in eating native toads. The Florida eastern hognose snake (Heterodon platirhinos) and southern hognose snake (Heterodon simus) are adapted to eating native toads (neither of these occur on Sanibel). However, native hognose snakes are wiped out when the cane toads infiltrate their range, due to the strong toxin. If you hold a southern toad or any true toad and they become threatened, they will ooze this irritant; if you get it in your eyes, they will burn and water for 20-30 minutes. Please wash your hands after handling any toad.


What You Can Do

There is a recording of the cane toad’s mating call at
http://graptemys.com/giant_toad.wav

If you see or hear a giant toad on Sanibel or Captiva, please report it to SCCF’s Wildlife Habitat Management office at 239-472-3984. First, and foremost, please take a picture of the toad if you can, so it can be verified.

The best case scenario is that this is a small isolated population. The removal of this species from Sanibel, if possible, is crucial to delicate species. We need help in identifying any other localities where these toads may be present. Sanibel (wildlife and citizens) cannot afford to have this species spread throughout the island.

Southern Toads

Please keep in mind that there is a similar native amphibian found on Sanibel. The southern toad (Anaxyrus terrestris) is also a true toad (Family Bufonidae). Southern toads are smaller than giant toads (averaging around 3” in length). Young giant toads and adult southern toads are similar in appearance and size. A major difference between the two toads is the size of the parotid glands. Southern toads have small parotoid glands as opposed to the very large glands on giant toads.  Southern toads also have "toxin" (more of an irritant) in their parotoid glands that is not as potent as cane toads. Many animals eat these toads, but that toxin is a deterrent to certain wildlife species. If you hold a southern toad and they are threatened, they will ooze the toxin; if you get it in your eyes, they will burn and water for 20-30 minutes.

More About Cane Toads

Like most other invasive amphibians and reptiles on the island, they did not migrate here by themselves.  More likely, they were accidentally brought here in mulch, pine straw, sod, plants, or even tadpoles hiding in a small pool of water on any object transported to the island.  Giant toads originate in South and Central refuge sccf staffAmerica.


Photo right: Refuge intern Cassie Cook and SCCF intern Stephanie Cappiello looking for Cane toads.

Cane toads were brought to Australia in the 1930s to control cane grubs in sugar cane fields. They did not control cane grubs and started eating smaller vertebrates. They have spread throughout northeastern Australia and are still a serious threat. They were released in sugar cane fields in Florida to control a larval form of a beetle as well, hence the name "cane toad." Just like in Australia, they escaped from the area and became established. Also, there is a record of approximately 100 being accidentally released in the 1950s in Miami by a pet dealer.

Updated 7/22/13