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SCCF: Cane toads multiplying fast in recent weeks

By Staff | Jun 24, 2020
SCCF Cane toad tadpole
SCCF Cane toad eggs
SCCF Cane toad

The heavy rains over the last few weeks in Southwest Florida have filled in many temporary or ephemeral wetlands. As with the native amphibian species, the exotic invasive anuran or frog species are taking advantage of many fish-less bodies of water to breed and deposit eggs that will quickly become tadpoles, which will transform into miniature terrestrial frogs or toads.

The exotic giant toad, also called the cane, marine, Bufo or faux toad, has been aggressively breeding on Sanibel and Captiva in the wetlands. Each toad can lay up 30,000-plus eggs, but will usually lay less than half of that. The poison of cane toads is lethal to most native wildlife species, as well as pet dogs and cats.

Cane toads were first discovered on Sanibel in 2013 during frog call surveys by the Sanibel-Captiva Conservation Foundation. At that time, they were localized to a couple of ephemeral wetlands near Middle Gulf Drive and Fulger Street. A quick response by SCCF, the J.N. “Ding” Darling National Wildlife Refuge, and city of Sanibel after detection showed promise in eliminating the new threat, but eggs were already deposited even though every visible breeding adult was collected.

Sanibel also has one native species of toad – the southern toad – that is easily differentiated from the cane toad by size as adults, but nearly impossible as metamorphosized toadlets or under 1 inch. The main difference is that cane toads have a pair of very large, triangular parotoid glands (poison glands) behind the eyes, bony ridges above the eyes, a more flattened face and can reach 6 inches in length.

Southern toads rarely exceed 3 inches, have small oval parotoid glands behind their eyes, a pair of cranial crests or ridges between the eyes on top of the head, and wider facial profile. The cranial crests form after they are about one inch in length, and toads smaller than that cannot be differentiated to species.