American Toad
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The American toad (''Anaxyrus americanus'') is a common species of
toad 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. A distinction between frogs and toads is not made in scientif ...
found throughout
Canada Canada is a country in North America. Its ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, covering over , making it the world's second-largest country by tot ...
and the eastern
United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territorie ...
. 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 ''Anaxyrus'' is a genus of true toads in the family Bufonidae. The genus is endemic to North and Central America. Some authors consider ''Anaxyrus'' to be a subgenus within ''Bufo ''Bufo'' is a genus of true toads in the amphibian family Bufo ...
'' instead of ''
Bufo ''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 ...
''.


Tadpoles

The eggs of the American toad are laid in two strings and can hatch in 2–14 days. When hatched the
tadpole A tadpole is the larval stage in the biological life cycle of an amphibian. Most tadpoles are fully aquatic, though some species of amphibians have tadpoles that are terrestrial. Tadpoles have some fish-like features that may not be found i ...
s 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 takes place usually to shaded areas of mid range and upland forests bordering the marshes from where they bred. Toadlets can be observed eating microscopic bugs as fast as they can in the ground area they roam 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 ''Chlorogonium'' is a genus of green algae in the family Haematococcaceae. This alga has a notable mutualistic relationship with the American toad, allowing the tadpoles to develop faster when covered with ''Chlorogonium''. See also *''Oophila ...
'' algae, which makes tadpoles develop faster than normal. 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.


Biogeography

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 The Isthmus of Panama ( es, Istmo de Panamá), also historically known as the Isthmus of Darien (), is the narrow strip of land that lies between the Caribbean Sea and the Pacific Ocean, linking North and South America. It contains the country ...
land bridge, presumably by means of
rafting Rafting and whitewater rafting are recreational outdoor activities which use an inflatable raft to navigate a river or other body of water. This is often done on whitewater or different degrees of rough water. Dealing with risk is often a ...
.


Subspecies

Races tend to
hybridize Hybridization (or hybridisation) may refer to: *Hybridization (biology), the process of combining different varieties of organisms to create a hybrid *Orbital hybridization, in chemistry, the mixing of atomic orbitals into new hybrid orbitals *Nu ...
with ''
Anaxyrus woodhousii Woodhouse's toad (''Anaxyrus woodhousii'') 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 overla ...
'' in their overlapping ranges.


Eastern American toad

The eastern American toad (''A. a. americanus'') is a medium-sized toad usually ranging in size from ; record . 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 Fowler's toad (''Anaxyrus fowleri'') 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 subspec ...
''. 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. Other species that may be confused with the eastern American toad are
Fowler's toad Fowler's toad (''Anaxyrus fowleri'') 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 subspec ...
, which has three or more warts in the largest dark spots, and in the far west of its range
woodhouse's toad Woodhouse's toad (''Anaxyrus woodhousii'') 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 ...
. 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 gland The parotoid gland (alternatively, paratoid gland) is an external skin gland on the back, neck, and shoulder of toads and some frogs and salamanders. It can secrete a number of milky alkaloid substances (depending on the species) known collective ...
s. 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 Bufotoxins are a family of toxic steroid lactones or substituted Substituted tryptamine, tryptamines of which some may or may not be toxic. They occur in the parotoid glands, skin, and poison of many toads (genus ''Bufo'') and other amphibians, an ...
, a poisonous substance meant to make the toad unpalatable to potential predators.
Bufotoxin Bufotoxins are a family of toxic steroid lactones or substituted Substituted tryptamine, tryptamines of which some may or may not be toxic. They occur in the parotoid glands, skin, and poison of many toads (genus ''Bufo'') and other amphibians, an ...
is a mild poison in comparison to that of other poisonous toads and frogs, but it can irritate human eyes and mucous membranes and is dangerous to smaller animals (such as dogs) when ingested. 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 Hibernation is a state of minimal activity and metabolic depression undergone by some animal species. Hibernation is a seasonal heterothermy characterized by low body-temperature, slow breathing and heart-rate, and low metabolic rate. It most ...
. Their diet includes
crickets Crickets are orthopteran insects which are related to bush crickets, and, more distantly, to grasshoppers. In older literature, such as Imms,Imms AD, rev. Richards OW & Davies RG (1970) ''A General Textbook of Entomology'' 9th Ed. Methuen 8 ...
,
mealworm Mealworms are the larval form of the yellow mealworm beetle, ''Tenebrio molitor'', a species of darkling beetle. Like all holometabolic insects, they go through four life stages: egg, larva, pupa, and adult. Larvae typically measure about or ...
s,
earthworm An earthworm is a terrestrial invertebrate that belongs to the phylum Annelida. They exhibit a tube-within-a-tube body plan; they are externally segmented with corresponding internal segmentation; and they usually have setae on all segments. Th ...
s,
ant Ants are eusocial insects of the family Formicidae and, along with the related wasps and bees, belong to the order Hymenoptera. Ants evolved from vespoid wasp ancestors in the Cretaceous period. More than 13,800 of an estimated total of 22 ...
s,
spider Spiders ( order Araneae) are air-breathing arthropods that have eight legs, chelicerae with fangs generally able to inject venom, and spinnerets that extrude silk. They are the largest order of arachnids and rank seventh in total species ...
s,
slug Slug, or land slug, is a common name for any apparently shell-less terrestrial gastropod mollusc. The word ''slug'' is also often used as part of the common name of any gastropod mollusc that has no shell, a very reduced shell, or only a smal ...
s,
centipede Centipedes (from New Latin , "hundred", and Latin , " foot") are predatory arthropods belonging to the class Chilopoda (Ancient Greek , ''kheilos'', lip, and New Latin suffix , "foot", describing the forcipules) of the subphylum Myriapoda, an ...
s,
moth Moths are a paraphyletic group of insects that includes all members of the order Lepidoptera that are not butterflies, with moths making up the vast majority of the order. There are thought to be approximately 160,000 species of moth, many of w ...
s, 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 The Canadian toad (''Anaxyrus hemiophrys''), also known as the Dakota toad, is a species of toad that ranges from the prairie regions of western Canada south to parts of the United States upper midwest. It belongs to the family Bufonidae, the "tr ...
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 The southern toad (''Anaxyrus terrestris'') 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 i ...
's, but in this species the cranial crests form two unique knobs.


Dwarf American toad

The dwarf American toad (''A. a. charlesmithi''), is a smaller version of the American toad, which reaches lengths of about , 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.


Hudson Bay toad

The Hudson Bay toad (''A. a. copei'') is a rare Canadian subspecies of ''A. americanus''. 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.


Inbreeding avoidance

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 Incest ( ) is human sexual activity between family members or close relatives. This typically includes sexual activity between people in consanguinity (blood relations), and sometimes those related by affinity (marriage or stepfamily), adoption ...
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.


Gallery

File:Newly metamorphosed American Toad.png, Newly metamorphosed American Toad (~5mm) at confluence of Keay Brook, Berwick, ME and the Salmon Falls River. File:Smallamericantoad.JPG, Approximately one week into adult cycle, shown in comparison to an adult female human hand File:Toadfells.jpg, Eastern American toad, seen from behind, shows characteristic markings and "warts" File:Bufo americanus Toad.JPG, Closeup of the Eastern American toad File:Red Bufo americanus.JPG, Young American toad File:Eastern american toad.jpg, Front view of Eastern American toad File:Bufo americanus Side.JPG, Side view of camouflaged ''A. americanus'' File:Eastern American toad (Sudden Tract).jpg, Eastern American toad (''A. a. americanus''), North Dumfries, Ontario File:American toad shedding skin.JPG, American toad eating its skin as it sheds File:American Toad singing.jpg, American toad chirp - mating call File:American Toad 8638.jpg, American toad feeding time File:American toad named "Betty".png, 5 year old female American toad. File:Toad Under Board.jpg, A closeup of an Eastern American toad seen in Tennessee.


See also

* European toad *
European green toad The European green toad (''Bufotes viridis'') is a species of toad found in steppes, mountainous areas, semi-deserts, urban areas and other habitats in mainland Europe, ranging from far eastern France and Denmark to the Balkans and Western Russi ...
*
Japanese toad The Japanese common toad, Japanese warty toad or Japanese toad (''Bufo japonicus'') is a species of toad in the family Bufonidae. It is endemic to Japan. Its natural habitats are subarctic forests, temperate forests, temperate shrubland, swamps ...


References


External links


B. americanus
at the
United States Geological Survey The United States Geological Survey (USGS), formerly simply known as the Geological Survey, is a scientific agency of the United States government. The scientists of the USGS study the landscape of the United States, its natural resources, ...
site
USDA – ''Bufo americanus''
– United States Department of Agriculture
Integrated Taxonomic Information System The Integrated Taxonomic Information System (ITIS) is an American partnership of federal agencies designed to provide consistent and reliable information on the taxonomy of biological species. ITIS was originally formed in 1996 as an interagenc ...
''.
Animal Diversity Web: ''Bufo americanus''
{{Taxonbar, from=Q694496 Anaxyrus Amphibians of the United States Amphibians of Canada Fauna of the Eastern United States Fauna of the Great Lakes region (North America) Amphibians described in 1836 Taxa named by John Edwards Holbrook