Canaan Conservation Area is located in Gasconade County, near Bland. Take Route A about 1.2 miles north from Bland to the Conservation Area's southern most access road.
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Scientific Name
Anaxyrus americanus americanus (eastern American toad) and A. americanus charlesmithi (dwarf American toad)
Family
Bufonidae (true toads) in the order Anura (frogs)
Description
American toads (Anaxyrus americanus) are well-known and occur statewide. Missouri has two subspecies: the eastern American toad in the northern half, and the dwarf American toad in the southern half.
- The eastern American toad (Anaxyrus americanus americanus), which occurs in the northern half of Missouri, is medium-sized (usually 2–3½ inches long, snout to vent) and has a wartlike, kidney-shaped gland (called the parotoid gland) behind each eye. The bony ridge above each eye usually does not touch the parotoid gland, but it may be connected to it by a small spur. Large black or dark brown spots on the back usually encircle one or two warts. A narrow, light stripe down the back may be present. The general color may be gray, greenish gray, or various shades of brown. The belly is white with dark gray mottling. The male's call is a sustained, high-pitched trill lasting 6–30 seconds.
- The dwarf American toad (Anaxyrus americanus charlesmithi), which lives in the southern half of Missouri, is only about 2 inches long, snout to vent, so it is generally smaller than the eastern American toad subspecies. Otherwise, it is very similar. But here are other distinguishing characters: Its ground color can be reddish brown, and the size and number of dark spots on the back are reduced or absent. The belly is cream colored with a small number of dark gray spots on the breast. Its call is similar to the eastern American toad, but it is slightly higher in pitch.
Note that the two subspecies of American toad mate with each other when they occur in the same area, so there is a wide band of intergradation between these two subspecies along a line from St. Louis to northern Joplin.
Similar species: The two subspecies of the American toad in Missouri have been known to hybridize with the Fowler’s toad (Anaxyrus fowleri) and the Rocky Mountain toad (Anaxyrus woodhousii woodhousii) in some parts of the state. The offspring of these crossbreedings are very difficult to identify because they often have characteristics of both species.
Members of the true toad family (Bufonidae) live nearly worldwide, except for New Zealand, Australia, Madagascar, and the polar regions. The family comprises 47 genera with more than 590 species. In the United States, there are 19 species of true toads, and all are members of the genus Anaxyrus. In Missouri, there are 4 species of true toads, with 1 additional subspecies.
True toads have dry skin compared to frogs. They have no teeth, lack extensive webbing on the hind feet, and have large, wartlike parotoid glands behind their eyes. Numerous “warts” over most of their bodies produce toxic skin secretions that are irritating to a predator’s mucous membranes.
Size
Adult length, eastern American toad (snout to vent): 2–3½ inches; occasionally to 6 inches. Females are generally larger than males. The dwarf American toad is smaller, averaging about 2 inches in length; see subspecies descriptions for discussion of their relative sizes.
Where To Find
The American toad species occurs statewide. The eastern American toad subspecies occurs throughout the northern half of the state, but it intergrades with and is replaced by the dwarf American toad subspecies in the southern half of the state. There is a wide band of intergradation between these two subspecies along a line from St. Louis to northern Joplin.
Habitat and Conservation
American toads can be found in about any habitat in Missouri, but they prefer rocky, wooded areas and often live along the edge of hardwood forests. They are also found in disturbed habitats, such as urban and suburban, agricultural, and mined sites. People often see them in backyards, parks, and gardens.
This species resides more in upland habitats compared to the equally common Rocky Mountain toad and Fowler’s toad, which occur more often in lowlands and river floodplains.
Individuals hide during the day under rocks and logs where there is loose, moist dirt, or they burrow into a depression where dead leaves have accumulated. Like most toads, this species becomes active at dusk.
All of Missouri’s species of true toads are primarily nocturnal, seeking shelter during the day among piles of dead leaves, under rocks and logs, or in loose soil.
Food
American toads eat earthworms and a wide variety of insects. Toads are well-known for their consumption of large numbers of insects. During summer nights, toads often catch and eat insects as they fall to the ground under outdoor lights.
Status
Missouri’s most common toads.
The scientific name for this species used to be Bufo americanus, but researchers in 2006 showed convincingly that some of the species formerly grouped together in the genus Bufo were different enough to warrant being separated into different genera. That is why this toad is now named Anaxyrus americanus.
Life Cycle
Life Cycle
In Missouri, male American toads begin calling on warm nights in mid-March and early April. Breeding generally peaks from late April into May, with calling activity continuing into July. Breeding sites include both temporary pools (such as sinkhole ponds and human-made ponds), and slow, shallow streams. The number of toads calling at a breeding site can vary greatly from year to year.
Eggs are laid in long, double strands and are deposited on the bottom in shallow water or entwined in aquatic plants. A female can lay 2,000–20,000 eggs, which hatch, in about a week, into tiny black tadpoles. The tadpoles often are found in dense aggregations in shallow water near the shore. The tadpoles remain in water until late June into July, when they transform into small toadlets about ½ inch long.
American toads are known to live about 4–5 years.
Human Connections
Contrary to superstition, toads do not cause warts on humans. They are harmless.
Despite toads' complexion and dour countenance, many people find them endearing.
During summer nights, toads help us by consuming insects and other small organisms that are pests or annoyances to us and our gardens.
Extensive, human-created habitat disturbance is one cause for hybridization to occur among toad species and subspecies.
The subspecies name of the dwarf American toad, charlesmithi, honors the biologist Charles Clinton Smith (1910–1966), a colleague of Arthur Bragg, who first described the subspecies. A native of Kansas, Smith taught at colleges in Kansas, Oklahoma, Louisiana, and Arkansas. He worked with the Civilian Conservation Corps and the Oklahoma Biological Survey and was a soil conservationist for the USDA.
Ecosystem Connections
Toads are predators that help keep populations of insects and other small animals in balance.
They, and especially their eggs, tadpoles, and young toadlets, become food for both aquatic and terrestrial predators ranging from water bugs to fish to grackles to raccoons. Even though American toads can lay a large number of eggs, there is no guarantee that the tadpoles will survive to metamorphosis. In one documented case, some 200,000 eggs that hatched in a pond over a two-year period resulted in no tadpoles surviving due to high predation.
American toad eggs and tadpoles can have a mutualistic relationship with green algae. A similar relationship has long been known with salamander eggs: The eggs of spotted salamanders, for example, usually have algae growing on the early stages of the developing embryos within the eggs. The algae apparently provides oxygen to the embryos, and the developing larvae provide carbon dioxide and waste products that can be used by the algae. But only recently has such a relationship been documented in toad tadpoles: the green algae Chlorogonium can occur in patches on the skin of American toad tadpoles.
There's a group of insects called toad bugs, which look a great deal like miniature toads. They even hop! They live along stream banks and, like their namesakes, are well camouflaged.
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American toad
Credit
MDC Staff
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Video of American toad in the wild.
Credit
Kevin Muenks
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Audio of an American Toad.
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About Reptiles and Amphibians in Missouri
Missouri’s herptiles comprise 43 amphibians and 75 reptiles. Amphibians, including salamanders, toads, and frogs, are vertebrate animals that spend at least part of their life cycle in water. They usually have moist skin, lack scales or claws, and are ectothermal (cold-blooded), so they do not produce their own body heat the way birds and mammals do. Reptiles, including turtles, lizards, and snakes, are also vertebrates, and most are ectothermal, but unlike amphibians, reptiles have dry skin with scales, the ones with legs have claws, and they do not have to live part of their lives in water.