American toad | |
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Specimen from Jacques-Cartier National Park, Quebec, Canada | |
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Class: | Amphibia |
Order: | Anura |
Family: | Bufonidae |
Genus: | Anaxyrus |
Species: | A. americanus |
Binomial name | |
Anaxyrus americanus (Holbrook, 1836) | |
Subspecies | |
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Range of A. americanus | |
Synonyms | |
Bufo americanusHolbrook, 1836 |
The American toad (Anaxyrus americanus) [3] 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 . [3] [4] [5]
A. americanus eggs are bicolored. They are often a roughly equal mixture of a black or brown with white or cream. The eggs are deposited in two long ropes that have been recorded to transcend 60 m in length. Single egg diameter ranges from 0.1 cm to 0.2 cm. [6] [ failed verification ]
The American toad lays between 2,000-20,000 eggs in two strings which hatch in 3-12 days. [7] The hatched tadpoles, while very small, are recognizable by their skinny tails in relation to the size of their round black bodies. They reach adulthood in 50–65 days. When metamorphosis is complete, the "toadlets" may stay in the water for a short period of time before transitioning to be mostly land based. Often times, groups of tadpoles reach the toadlet stage at once and a begin a mass migration to higher ground. Typically, toadlets migrate to shaded areas in the mid-range and upland forests that border the marshes where they were bred. Toadlets can be observed eating microscopic bugs in their roaming ground between various vegetation; they are also known to eat ants, spiders, slugs and worms. Studies have shown that they have a mutualistic relationship with Chlorogonium algae, which makes tadpoles develop faster than normal. [8] Leaf litter from invasive plants like autumn olive or purple loosestrife in the larval nursery can increase the burden of trematode parasite infestation among tadpoles. This is possibly mediated by faster development of tadpoles in these aquatic environments than in nurseries with leaves of native black huckleberry or swamp loosestrife. [9]
Tadpoles have several mechanisms to reduce predation. [10] 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 predation. Fish have been reported to die after consuming one tadpole; however, most fish quickly learn to avoid eating American toad tadpoles. [11]
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. [12]
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); [13] the record length for an eastern American toad is 11.1 cm (4.4 in). [14] 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 that lasts between 6–30 seconds [14] and sounds similar to a ringing telephone. Males call for an average of 6-7 nights during their breeding period. [15] Females show preference for call efforts (rate × duration), but not call frequency. [16] 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.
Other species that may be confused with the eastern American toad are Fowler's toad, which has three or more warts in the largest dark spots, and in the far west of its range woodhouse's toad. Fowler's toad can be especially difficult to identify in comparison to the eastern American toad but one difference is that it never has a spotted belly and both cranial crests touch the parotoid glands. Also, Fowler's toads are very fast hoppers (bursts of 5–10 fast hops) in comparison to Eastern toads lethargic, casual hopping and walking locomotion. In the eastern American toad these crests almost never touch the parotoid glands, which secrete bufotoxin, a poisonous substance meant to make the toad unpalatable to potential predators. Bufotoxin is a mild poison in comparison to that of other poisonous toads and frogs, but it can irritate human eyes and mucous membranes [17] and is dangerous to smaller animals (such as dogs) when ingested. [18]
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, [14] 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.[ original research? ] 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. [11] 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 may be confused with the Canadian toad in the area where they overlap, but the cranial crests in the American toad do not join to form a raised "boss" (bump) like they do in the Canadian toad. Its range also overlaps with the southern toad's, but in this species the cranial crests form two unique knobs.
The dwarf American toad (A. a. charlesmithi), is a smaller version of the American toad, which reaches lengths of about 6 cm (2+1⁄4 in), is generally a dark reddish color ranging to light red in some specimens in isolated populations. The spots on the back are reduced or absent, and when present they contain a few small red warts and a black ring around it like in the normal American toad. The warts are always darker than the skin of the toad. Some specimens have a white dorsal line in the middle of their backs. The ventral surface or belly is usually cream colored with a few dark spots in the breast area. This subspecies can be distinguished from the above-mentioned species in the same manner as for the eastern American toad. The southwestern portion of the Dwarf American toad's range overlaps with that of the Gulf Coast toad. The latter species is distinguished by the presence of a dark lateral stripe as well as a deep "valley" between its prominent cranial crests. It eats mainly spiders, worms and small insects.
The Hudson Bay toad (A. a. copei) is a rare Canadian subspecies of A. americanus. [19] This subspecies of the American toad has been seen in the northern parts of Ontario where there are a few isolated populations. These northern dwarf toads mostly have the red coloring on the sides of their bodies and have an unusually high number of warts for the subspecies. Interbreeding with eastern American toads caused this subspecies to lose the red coloring on their backs.
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. [20] 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. [20]
The cane toad, also known as the giant neotropical toad or marine toad, is a large, terrestrial true toad native to South and mainland Central America, but which has been introduced to various islands throughout Oceania and the Caribbean, as well as Northern Australia. It is a member of the genus Rhinella, which includes many true toad species found throughout Central and South America, but it was formerly assigned to the genus Bufo.
Toad is a common name for certain frogs, especially of the family Bufonidae, that are characterized by dry, leathery skin, short legs, and large bumps covering the parotoid glands.
Bufo is a genus of true toads in the amphibian family Bufonidae. As traditionally defined, it was a wastebasket genus containing a large number of toads from much of the world but following taxonomic reviews most of these have been moved to other genera, leaving only seventeen extant species from Europe, northern Africa and Asia in this genus, including the well-known common toad. Some of the genera that contain species formerly placed in Bufo are Anaxyrus, Bufotes, Duttaphrynus, Epidalea and Rhinella.
The common toad, European toad, or in Anglophone parts of Europe, simply the toad, is a toad found throughout most of Europe, in the western part of North Asia, and in a small portion of Northwest Africa. It is one of a group of closely related animals that are descended from a common ancestral line of toads and which form a species complex. The toad is an inconspicuous animal as it usually lies hidden during the day. It becomes active at dusk and spends the night hunting for the invertebrates on which it feeds. It moves with a slow, ungainly walk or short jumps, and has greyish-brown skin covered with wart-like lumps.
The western toad is a large toad species, between 5.6 and 13 cm long, native to western North America. A. boreas is frequently encountered during the wet season on roads, or near water at other times. It can jump a considerable distance for a toad. Breeding occurs between March and July in mountainous areas, and as early as January in lower-elevation regions. The female lays up to 17,000 eggs stuck together in strings that adhere to vegetation and other objects along water edges.
The red-spotted toad, formerly Bufo punctatus, is a toad in the family Bufonidae found in the southwestern United States and northwestern Mexico.
The southern toad is a true toad native to the southeastern United States, from eastern Louisiana and southeastern Virginia south to Florida. It often lives in areas with sandy soils. It is nocturnal and spends the day in a burrow. Its coloring is usually brown but can be red, gray, or black. It is approximately 8 cm (3 inches) long.
Holdridge's toad, formerly Bufo holdridgei, is a species of toad endemic to Costa Rica. In October 2008, it was declared extinct by the International Union for Conservation of Nature in its Red List since the species had not been seen since 1987, despite years of extensive searches. However, the species was rediscovered in 2010 by a Costa Rican herpetologist and is now classified as critically endangered. It is believed that the species is most threatened by the presence of the chytrid fungus in its habitat.
Woodhouse's toad is a medium-sized true toad native to the United States and Mexico. There are three recognized subspecies. A. woodhousii tends to hybridize with Anaxyrus americanus where their ranges overlap.
The boreal toad is the nominate subspecies of the western toad. They are commonly found in the western U.S. and western Canada. Boreal toad populations have declined recently due to an emerging amphibian disease, chytrid fungus. The boreal toad is currently listed as an endangered species by Colorado and New Mexico. It is known in Colorado as the only alpine species of toad.
Anaxyrus fowleri, Fowler's toad, is a species of toad in the family Bufonidae. The species is native to North America, where it occurs in much of the eastern United States and parts of adjacent Canada. It was previously considered a subspecies of Woodhouse's toad.
The Canadian toad, also known commonly as the Dakota toad, is a species of toad that ranges from the prairie regions of western Canada south to parts of the upper midwest of the United States. It belongs to the family Bufonidae, the "true" toads. Its specific name is derived from the Latin word hemiophrys, meaning eyebrow, which refers to its pronounced cranial crest between and behind the eyes. Anaxyrus hemiophrys displays the typical toad characteristics: it lacks a tail and teeth, it has a horizontal pupil, and its dry skin is thick and warty.
The Rocky Mountain toad or western Woodhouse's toad is a subspecies in the Woodhouse's toad subgroup. It can be identified by its light middorsal stripe, prominent cranial crests, and elongate parotoid glands. The belly is usually white or yellowish with dark flecks between the forelegs
The Yosemite toad is a species of true toad in the family Bufonidae. Endemic to the Sierra Nevada of California, the species ranges from the Alpine County to Fresno County. Yosemite toads are only found in the montane to subalpine elevational zone of 1,950–3,445 m (6,398–11,302 ft) asl. The Yosemite toad is similar to the nearby western toad, but in many ways adapted to a high elevation lifestyle. It was initially described during the Grinnell Survey of California, by an undergraduate student of Joseph Grinnell named Charles Camp.
Rhinella jimi is a species of toads in the family Bufonidae. It is endemic to northeastern Brazil and known between Bujaru in northeastern Pará and Maranhão in the north, south to Bahia and Vitória, Espírito Santo. Prior to its description in 2002, it was confused with Rhinella schneideri. The specific name jimi honors Jorge Jim, a Brazilian herpetologist. Common name Jimi's toad has been coined for it.
The Arizona toad is a species of toad in the family Bufonidae. It is endemic to the south-western United States, where its natural habitats are temperate lowland forests, rivers and streams, swamps, freshwater marshes, freshwater springs, ponds, open excavations, irrigated land, and seasonally flooded agricultural land.
The oak toad is a species of toad in the family Bufonidae. It is endemic to the coastal regions of southeastern United States. It is regarded as the smallest species of toad in North America, with a length of 19 to 33 mm.
The raucous toad, also known as Ranger's toad, is a species of toad from Southern Africa.
Sclerophrys reesi, also known as Merara toad or Rees' toad, is a species of toad in the family Bufonidae. It is endemic to southern Tanzania and is only known from the Kihansi–Ulanga River floodplain from elevations of 200–500 m (660–1,640 ft) above sea level. It is named after Allen Rees, a principal game warden for the Tanzanian Wildlife Department who collected the type series.
The Hot Creek toad is a species of toad in the family Bufonidae. It is endemic to Nye County in the state of Nevada in the United States.