American Toad (Bufo americanus)
Order: Anura, Family: Bufonidae
The American toad is located in the Midwestern to eastern region of North America. They range east of the Rocky Mountains to the Atlantic Coast, and from mid-Canada to Mexico.
I. GEOGRAPHIC RANGE
II. PHYSICAL CHARACTERISTICS
- The American toad is located in the Midwestern to eastern region of North America. They range east of the Rocky Mountains to the Atlantic Coast, and from mid-Canada to Mexico.
III. FOOD HABITS
- Tadpoles are dark, almost black, with smooth skin, round bodies and a somewhat rounded tail. They grow to over a centimeter in length before transforming.
- Newly-metamorphosed toads are usually 0.8-1.3 cm long when they first emerge. Their coloration is similar to the adult toad, which is mottled brown with dark spots and bumps.
- Most adult American toads grow to two to three and one half inches (50-75 mm) long, measured from snout to vent. They have short legs and round bodies. There are four toes on the front legs. Five toes are connected together by webbing on their hind legs.
- The American toad's pupils are oval and black with a circle of gold around them.
- The skin of the American toad is very thick, rough, and darkly spotted. Each spot has one or two prominent "warts". These warts can be colored red and yellow. This toad's skin color is normally a shade of brown but toad skin color changes depending on the temperature, humidity and the amount of stress the toad is experiencing. The color change ranges from yellow to brown to black. The bellies are a white or yellow color.
- The sexes can be distinguished in three ways. Males have dark colored throats, of black or brown, and females have white throats. Females are larger than male American Toads. Females are overall a lighter color than the male toads.
- Both tadpoles and adults have defensive chemicals in their skin.
- These toads are generalists, eating a wide variety of insects and other invertebrates they find at night, including earthworms and slugs. An American toad can eat one hundred insects in a night.
- Most prey is captured with their wide and sticky tongues. They also may use their front legs in order to eat larger food. They grasp their food and push it into their mouths.
- After mating takes place, the female lays her eggs, in the water, in long rows. Each female can produce 2,000-20,000 eggs. When this row of eggs is stretched it generally measures between six and 20 m long (20-66 ft.) Each individual egg is 1.5 mm in diameter. The eggs mature fastest at higher temperatures.
- Breeding occurs in the months of March or April, but may extend into July. It usually triggered by warming temperatures and longer days. The males always arrive to the mating grounds well ahead of females. They choose shallow wetlands, ponds, lakes and slow-moving streams. After finding a suitable area, the male toads begin calling the females. Females may choose their mates by assessing the males breeding calls as well as the quality of the defended breeding territory.
- Male toads get dark, horny pads on their first and second two toes on their forelegs. This helps them hold on to the back of a female. This coupling is called amplexus. The female, with the male on her back, moves to a suitable location in the water to lay eggs. When she releases her eggs, he releases sperm to fertilize them. Like most frogs and toads, fertilization is external.
- There is no parental care in this species. Once the eggs are laid and fertilized, the parents ignore them.
- American toads are mainly nocturnal, and are most active when the weather is warm and humid.
- Toads do not drink water but soak it in, absorbing moisture through their skin. American Toads, while still growing, shed their external skin every couple of weeks or so. Older frogs lose their skin around four times yearly. The skin peels off in one piece and is collected under its tongue, where it is then gulped down.
- During the day American toads hide under rocks or logs or dig into dead leaves and soil. In regions with a cold winter, American toads dig deeper to hibernate. When digging they back in as they push out dirt with their back legs.
VII. ECONOMIC IMPORTANCE FOR HUMANS
- American toads require a semi-permanent freshwater pond or pool for their early development. They also require dense patches of vegetation, for cover and hunting grounds. Given these two things and a supply of insects for food, the American toad can live almost everywhere, ranging from forests, fields, backyards and gardens of homes.
American toads eat many species of pest insects and other invertebrates. They are widely considered friends to gardeners and farmers. The toxins produced by their skin may also prove useful in medical research.
IX. OTHER COMMENTS
- The American toad has no special conservation status, as it still a common species in most of its range. Some populations have declined in recent years, possibly due to pollution.
- Contrary to popular folklore, you will not get warts if you touch a toad. However, the defensive chemicals in a toad's skin are toxic to humans, so it is important to wash one's hands carefully after handling this amphibian.