The cranial crest of the American Toad is pronounced and either disconnected to the paratoid gland or only connected via a spur while the Fowler's Toad has a much less prominent cranial crest that sits directly on top of the paratoid gland.
(2009) argue against this, instead suggesting that Anaxyrus be recognized as subgenera of the intact Bufo. The American Toad belongs to the family Bufonidae, which is diverse worldwide and is represented in Indiana by a total of two species.
The American Toad has two recognized subspecies present in Indiana--the Eastern American Toad ( Bufo americanus americanus) and the Dwarf American Toad ( Bufo americanus charlesmithi ). See the Distribution description above for details on where each of these subspecies is found. Frost et al. (2006) recommended placing these toads in the genus Anaxyrus, but Pauly et al. (2009) argue against this, instead suggesting that Anaxyrus be recognized as subgenera of the intact Bufo. The American Toad belongs to the family Bufonidae, which is diverse worldwide and is represented in Indiana by a total of two species.
American Toads have a high pitched trill that generally lasts a few seconds, but may last up to 30 seconds. When picked up, males will often give a high pitched peeping call or broken trill that is also given when a male grabs another male by mistake during breeding. Listen to the call courtesy of the Indiana DNR.
Adults are large, stocky toads with a wide variety of red, brown, and gray color variations. There may be some dark blotches dorsally, but these blotches encompass only one or two warts. Ventrally, there is usually some dark mottling or speckling and the legs have some indistinct banding.
Distribution. The American Toad occurs throughout much of eastern Canada and the eastern United States, but is absent from most of the southeastern states. This species occurs throughout Indiana except for much of the southwestern lowlands. The dwarf American Toad ( Bufo a. charlesmithi) variant is restricted to southern Indiana where many ...
Amplexus takes place in shallow, calm water. The male clasps the female and as the females expels strands of eggs, the male fertilizes them externally. Oftentimes multiple males will attempt to clasp one female, resulting in a ball of toads clasped together in a breeding frenzy.
Frogs, represented by more than 6289 species, have always represented a great challenge to systematists, as their evolutionary history evidently includes explosive radiations, along with high levels of both convergence and extreme morphologic derivation. Because attempts to recover the phylogeny of frogs with morphologic data alone have generally failed, molecular data have been crucial in shaping our understanding of this complex phylogeny. Building on the foundation of the efforts by Frost et al, 3 numerous studies have been produced 11,20 and are greatly increasing the knowledge about this vast and taxonomically difficult group. As soon as an agreement on a phylogeny of frogs is reached, numerous taxonomic changes will be forthcoming. Some stakeholders have expressed frustration about changes already proposed, such as when long-familiar species such as Rana catesbeiana and Bufo americanus suddenly appeared as Lithobates catesbeianus and Anaxyrus americanus. Simply put, such changes are necessary and important so that a taxonomy that is both informative and internally consistent can be used when communicating about amphibians. Figure 19-5 summarizes the agreement among recent studies on frog phylogeny. Polytomies, or unresolved branches, represent areas of the tree where recent analyses have produced conflicting results or poor statistical support; in this sense, the phylogeny shown here is conservative.
Although available data demonstrate wide variability, amphibians appear among the classes of soil-dwelling organisms that are most impacted by fire passage, which chiefly depends on fire severity and season.
The best-studied example of hormone-dependent phonotaxis occurs in female anurans. In many species, such as the Túngara frog ( Physalaemus pustulosus) and the American toad ( Bufo americanus ), males emit loud vocalizations that are amplified by specialized structures called ‘vocal sacs’ and can be heard at a great distance. Because recordings of calls played from a speaker can induce female phonotaxis both in the field and in the lab, behavioral assays are a popular way to study it. Females do not perform this behavior unless they are gravid, so the early experiments had to be done using females collected as they began to mate with males. In an effort to circumvent this problem, Picker (1980) discovered that injections of human chorionic gonadotropin induced phonotaxis in female African clawed frogs ( Xenopus laevis ), thereby showing some of the first evidence that this behavior has a hormonal basis. Human chorionic gonadotropin acts by mimicking the actions of the gonadotropin luteinizing hormone on the ovary to induce the secretion of estradiol and progesterone. The induction of estradiol secretion may be the more important effect of human chorionic gonadotropin in the frog model; experimental elevation of estradiol to breeding levels induces phonotaxis in ovariectomized females ( Chakraborty and Burmeister, 2009 ). Concurrent administration of progesterone does not increase phonotaxis any further, suggesting that estradiol alone is sufficient.
Fig. 2. A female white-crowned sparrow performs a copulation solicitation display (CSD). This display signals to the male that she is in reproductive condition. Reprinted with permission from the Journal of Neuroendocrinology 10 (8), cover material.
Four studies on the effects of phenol on amphibian development were located; one used a short-term embryo exposure, and three used embryo and larval exposures.
Frogs communicate in modalities besides the auditory one. Tadpole social behavior, for example, is strongly influenced by olfactory cues. In aggregations of tadpoles of the American toad, Bufo americanus, siblings are more likely to be found in proximity to one another than to nonsiblings. These and many species of tadpoles can discriminate sib from nonsib and paternal half-sib from sib using odor cues that become incorporated into the jelly matrix of the nest.
The vocal sac can also serve as a visual cue. Male poison frogs, Epipedobates femoralis, attack models with pulsating vocal sacs. In a diurnal frog from Tanzania, Phrynobatrachus krefftii, males silently inflate their bright yellow vocal sacs as a visual signal ( Figure 5 ). The vocal sac can also contribute to multimodal communication.
Given these two things and a supply of insects for food, American toads can live almost everywhere, ranging from forests to flat grassland. Females when caught are silent and easily tamed, adapting to terrarium life readily, while the smaller males are readily communicative.
American toads require a semi-permanent freshwater pond or pool with shallow water in which to breed, to gather their water supplies in times of drought or as a routine, and 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, American toads can live almost everywhere, ranging from forests to flat grassland. Females when caught are silent and easily tamed, adapting to terrarium life readily, while the smaller males are readily communicative. The smaller males do not adapt well to terrarium life and should be released after a few days of observation. Adult toads are mostly nocturnal, although juveniles are often abroad by day. When it rains, these toads will become active and can be observed eating robustly worms and insects leaving their burrows and walking in front of an opportunist toad. These toads are 'creatures of habit' once they have a certain area they prefer to live within... an acre of wooded forest with water in proximity for soaking, a home with cool ledges and window wells; they commonly seek cover in burrows, under boardwalks, flat stones, boards, logs, wood piles, or other cover. When cold weather comes, these toads dig backwards and bury themselves in the dirt of their summer homes, or they may choose another site in which to hibernate. Their diet includes crickets, mealworms, earthworms, ants, spiders, slugs, centipedes, moths, and other small invertebrates. Some of these toads have been known to live over 30 years and currently a female specimen (over 13 centimeters long) is living healthily into her late 30s. Another female toad of 17 centimeters is known to have existed in Wisconsin from Washington Island on Lake Michigan.
The eastern American toad ( A. a. americanus) is a medium-sized toad usually ranging in size from 5–9 cm (2.0–3.5 in); record 11.1 cm (4.4 in). The color and pattern is somewhat variable, especially for the females. Skin color can change depending on habitat colors, humidity, stress, and temperature. Color changes range from yellow to brown to black, from solid colors to speckled. Their breeding habits are very similar to Anaxyrus fowleri. The call or voice of a breeding male is a high trill, lasting 6–30 seconds, similar to a ringing telephone. They hibernate during the winter. The eastern American toad has spots that contain only one to two warts. It also has enlarged warts on the tibia or lower leg below the knee. While the belly is usually spotted, in some areas many are, and it is generally more so on the forward half (in some rare individuals there may be few or no spots). This subspecies of the American toad has no or very little markings on it. The spades on the back legs are blackish. Some toads of this subspecies have a more pervasive red and deep brown color, many with red warts on their bodies. Also eastern American toads have parotoid glands that are the same color as the surrounding skin. The glands don't usually have any patterning on them.
The spades on the back legs are blackish. Some toads of this subspecies have a more pervasive red and deep brown color, many with red warts on their bodies. Also eastern American toads have parotoid glands that are the same color as the surrounding skin. The glands don't usually have any patterning on them.
The eggs of the American toad are laid in two strings and can hatch in 2–14 days. When hatched the tadpoles are recognizable by their skinny tails in relation to the size of their black bodies. They may advance to adulthood in 50–65 days.
Tadpoles have several mechanisms to reduce predation. They avoid predators by swimming in very shallow water often with thick grass vegetation, and by swimming close together in schools during the day . Tadpoles also produce toxic chemicals in their skin that discourage some potential predators. Fish have been reported to die after consuming one tadpole; however, most fish quickly learn to avoid eating American toad tadpoles. The tadpoles are also very small and they are a solid black color.
Based on DNA sequence comparisons, Anaxyrus americanus and other North American species of Anaxyrus are thought to be descended from an invasion of toads from South America prior to the formation of the Isthmus of Panama land bridge, presumably by means of rafting.
Their primary predators as adults are snakes including garter and hognose snakes. The American toad lives throughout most of Minnesota. They are found in diverse habitats, including woodlands, grasslands, and various wetlands. Like all frogs and toads, this species lays its eggs in freshwater wetlands.
Anaxyrus americanus (formerly Bufo americanus) The back of an American toad. The two large, kidney-shaped glands on the back of the head are called parotoid glands, and can secrete toxins when the toad is threatened.
Toadlets are less than 0.5 inch (1 cm) in length when they transform. American toads can secrete a bitter tasting toxin through a pair of glands, called parotoid glands. These glands look like two enlarged, kidney-shaped ‘warts’ sitting on the back of the head. The toxicity of parotoid secretions vary by toad species.
The American toad is a member of the ‘true toad’ family, Bufonidae, and is the most common toad in Minnesota. It ranges in color from dark brown to tan, and some have a light line down the middle of the back. Along the back, they have dark, brown-to-black splotches associated with bumps, commonly referred to as warts.
Males and females can most easily be distinguished by size and throat color; male American toads are smaller than females, and have dark coloration on the throat. The American toads’ body length (not including legs) varies from 2-3.5 inches (5-9 cm). What they eat.
They will emerge from dormancy typically in late April and move to breeding pools soon after, from early May to mid-June. How they’re doing. The American toad is not listed as threatened or endangered on state or federal lists. In Minnesota, populations are considered stable.
The toxicity of parotoid secretions vary by toad species. To defend itself from predators, an American toad will inflate itself to appear larger. Hognose snakes feed almost exclusively on toads and can use their rear-facing fangs to deflate a toad that has inflated itself in defense.
The American toad (Anaxyrus americanus ) is a common species of toad found throughout Canada and the eastern United States. It is divided into three subspecies: the eastern American toad (A. a. americanus), the dwarf American toad (A. a. charlesmithi) and the rare Hudson Bay toad (A. a. copei). Recent taxonomic treatments place this species in the genus Anaxyrus instead of Bufo.
The eggs of the American toad are laid in two strings and can hatch in 2–14 days. When hatched the tadpoles are recognizable by their skinny tails in relation to the size of their black bodies. They may advance to adulthood in 50–65 days. When metamorphosis is completed, the "toadlets" may stay in the water for a short period of time before they become mostly land based. Often entire groups of tadpoles reach the toadlet stage at once and a mass migration to higher ground take…
Based on DNA sequence comparisons, Anaxyrus americanus and other North American species of Anaxyrus are thought to be descended from an invasion of toads from South America prior to the formation of the Isthmus of Panama land bridge, presumably by means of rafting.
Races tend to hybridize with Anaxyrus woodhousii in their overlapping ranges.
The eastern American toad (A. a. americanus) is a medium-sized toad usually ranging in size from 5–9 cm (2.0–3.5 in); record 11.1 cm (4.4 in). The color and pattern is somewhat variable, especially for the females. Skin color can change depending on habitat colors, humidity, stress, and temperature. Color changes range from yellow to brown to black, from solid colors to speck…
Toads display breeding site fidelity, as do many other amphibians. Individuals that return to natal ponds to breed will likely encounter siblings as potential mates. Although incest is possible, Anaxyrus americanus siblings rarely mate. These toads likely recognize and actively avoid close kins as mates. Advertisement vocalizations by males appear to serve as cues by which females recognize their kin.
• European toad
• European green toad
• Japanese toad
• B. americanus at the United States Geological Survey site
• USDA – Bufo americanus – United States Department of Agriculture Integrated Taxonomic Information System.
• Animal Diversity Web: Bufo americanus