Toads everywhere !
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| Illustrations from U.S. Fish and Wildlife Service. |
The marine toad (Bufo marinus) is a recent introduction to American Samoa. It was purposely brought here in 1953 to control mosquitos or insect pests that attack taro.
The toads (lage) were brought from Hawaii and introduced into artificial ponds at Taputimu on Tutuila. From there, stocks were liberated in Tafuna and Utulei. The toads then expanded their range to include all of Tutuila, from sea level to the top of Mt. Alava. Fortunately, they have not yet been transported to Manu'a or to western Samoa.
The
toads breed year-round here. All they need is standing fresh or slightly
brackish water in which to lay their eggs. Thousands of eggs that look
like a string of black and white pearls are laid by each female. Within
a week the eggs hatch into small black tadpoles that feed voraciously
on aquatic plants. The tadpoles look defenseless but are thought to be
toxic to birds and other animals. Within a month these tadpoles develop
legs and change into adult toads.
As adults, they typically hide under boards or vegetation during the heat of the day and emerge at night to feed on insects and other invertebrates. They eat snails, millipedes, centipedes, spiders, roaches, moths, flies, caterpillars, termites, beetles, ants, earthworms, grasses, and even an occasional small toad.
How many toads inhabit Tutuila Island and how many bugs do they consume each night? In a wildlife study conducted in 1976, biologists estimated that over 2 million toads lived here with us. Some rough calculations suggest that these toads consume about 5 tons of bugs every night!
To some people it might appear that the toad is beneficial. One must keep in mind, however, that many of those insects would have been eaten by native birds and perhaps by the small insect-eating sheath-tailed bat (pe'ape'avai) that is now extremely rare in American Samoa. No one has examined the actual impacts the toads are having on our native wildlife, but there are many examples of introduced species causing the extinction of native plants and animals by out-competing them for food or other resources.
Another
concern involving the toad is its toxic skin glands. The adults have
two large parotid glands on their “shoulders” that secrete a creamy white
fluid when handled. These secretions are highly toxic if eaten, rubbed
into the eyes, or brought into contact with mucous membranes. Dogs have
died when they mouthed these toads. In addition, a high incidence of
the salmonella bacteria occurs in toads, thus an abundance of toads near
drinking water supplies may lead to bacterial contamination.