May 27, 2015

AMERICAN TOADS

AMERICAN TOADS
What do they look like?
American toads have short legs, stout bodies, and thick skins with noticeable warts. These warts can be colored red and yellow. The warty skin contains many glands that produce a poisonous milky fluid, providing these toads with excellent protection from many of their predators. This poison is only harmful if it is swallowed or if it gets in the eyes, but it can make many animals very sick. (Dickerson, 1906; Le Clere, 2000; Matson, 2002; Oliver, 1955)

The skin color of American toads is normally a shade of brown, but it can also be red with light patches, olive, or gray. The bellies are a white or yellow color. Toad skin color changes depending on temperature, humidity, and stress. The color change ranges from yellow to brown to black. American toads have four toes on each front leg and five toes connected together by a webbing on each hind leg. The pupils of American toads are oval and black with a circle of gold around them. The sexes can be distinguished in two ways. Males have dark colored throats, of black or brown, while females have white throats and are lighter overall. Also, female American toads are larger than male American toads. American toads are between 50 and 100 mm in length but are usually around 75 mm. American toads can be distinguished from other species of toads by the presence of several dark spots on their backs which contain only one or two warts each. These black spots are sometimes circled with white or yellow. Some types of American toads have a prominent ridge on the top of their heads. (Dickerson, 1906; Le Clere, 2000; Matson, 2002; Oliver, 1955)

The eggs of American toads are black on top and white on the bottom (countershaded), and embedded in long strings of clear sticky gel. The larvae that hatch from eggs are called "tadpoles." They are dark (almost black) with smooth skin, round bodies, and a somewhat rounded tail. Like adult toads, larvae have defensive chemicals in their skin. They grow to over a centimeter in length before transforming. Newly-metamorphosed toadlets are usually 0.8 and 1.3 cm long when they first emerge. Their coloration is similar to that of adult toads. (Dickerson, 1906; Le Clere, 2000; Matson, 2002; Oliver, 1955)

Other Physical Features ectothermic heterothermic bilateral symmetry poisonous
Sexual Dimorphism female larger sexes colored or patterned differently
Range length
50 to 102 mm
1.97 to 4.02 in
Average length
75 mm
2.95 in
Where do they live?
American toads, Anaxyrus americanus, are only native to the Nearctic region. They are found throughout large portions of North America. They are generally not present in the most southern states. These toads have an immense ability to adapt to their surroundings as long as there is a source of semi-permanent water for them to use in the breeding season. This quality has allowed them to successfully colonize suburban and agricultural areas. (Dickerson, 1906; Oliver, 1955)

Biogeographic Regions nearctic native
What kind of habitat do they need?
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, American toads can live almost everywhere, ranging from forests to backyards. They are common in gardens and agricultural fields. During daylight hours they seek cover beneath porches, under boardwalks, flat stones, boards, logs, wood piles, or other cover. When cold weather comes, these toads dig backwards into their summer homes or may choose another site in which to hibernate. (Le Clere, 2000; Lerner, June 13 1998; Matson, 2002; Rakestraw, 1998)

These animals are found in the following types of habitat temperate terrestrial freshwater
Terrestrial Biomes chaparral forest rainforest scrub forest mountains
Aquatic Biomes lakes and ponds rivers and streams
Wetlands marsh swamp bog
Other Habitat Features urban suburban agricultural riparian
How do they grow?
Female American toads lay their eggs in freshwater. Hatching occurs 3 to 12 days after laying, depending on the temperature of the water. The tadpoles group together and feed and grow for 40 to 70 days.

When the tadpoles hatch they have gills located on the sides of their heads just posterior to their mouths. During the first 20 days the tadpoles start to form their hind legs. The legs grow slowly, but continuously. After 30 to 40 days the front legs, which were previously covered by a layer of skin, appear. At the same time that the front legs emerge, the tadpoles' gills disappear, and the tadpoles start to breathe "atmospheric" air. Between the last two or three days of development, they complete their metamorphosis, resorbing their tails and strengthening their legs. They also stop eating plants in favor of animal matter.

Newly-metamorphosed toads stay near their pond for a few days (or longer if the climate is dry), and then disperse and begin to live primarily on land. American toads continue to grow until they reach their full adult size of approximately 75 mm.

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. (Dickerson, 1906; Matson, 2002; Oliver, 1955)

Development - Life Cycle metamorphosis
How do they reproduce?
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 on the mating grounds well ahead of females. They congregate in shallow wetlands, ponds, lakes and slow-moving streams. After finding a suitable area, the male toads establish territories and 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.

Mating System polygynous polygynandrous (promiscuous)
After mating takes place, the females lay their eggs in the water, in long spiral tubes of jelly. They lay 4000 to 8000 eggs in two rows. When each row of eggs is stretched it generally measures between between six and twenty meters long (20 to 66 ft.). Each individual egg is 1.5 mm in diameter. The eggs mature fastest at higher temperatures. They generally hatch in 3 to 12 days. After developing for 40 to 70 days, the tadpoles transform into adults. This usually takes place from June to August, depending on location. They reach sexual maturity at around 2 to 3 years of age.

Key Reproductive Features iteroparous seasonal breeding gonochoric/gonochoristic/dioecious (sexes separate) sexual fertilization external oviparous
How often does reproduction occur?
American toads breed from once yearly.
Breeding season
American toads breed from March to July each year, depending on location.
Range number of offspring
4000 to 8000
Range time to hatching
2 to 14 days
Range age at sexual or reproductive maturity (female)
2 to 3 years
Range age at sexual or reproductive maturity (male)
2 to 3 years
Female toads provide nutrients for their eggs inside their bodies. Once the eggs are laid and fertilized, the parents ignore them.

Parental Investment pre-fertilization provisioning protecting female
How long do they live?
In the wild most American toads probably don't survive more than a year or two. The majority die before transforming from tadpoles into toadlets. However, they are capable of living much longer. Some toads have lived longer than 10 years in the wild. There is a documented account of a captive toad that lived to the ripe old age of 36 and was killed by mistake. (Dickerson, 1906; Harding, 1997; Oliver, 1955)

Range lifespan
Status: wild
0 to 10 years
Average lifespan
Status: wild
< 1 years
Range lifespan
Status: captivity
0 to 36 years
How do they behave?
American toads are mainly nocturnal. They are most active when the weather is warm and humid. They are solitary, congregating only at breeding ponds in the early summer and late spring. 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, pushing out dirt with their back legs.

(Harding 1997, Mullin, 1998; Dickerson, 1906) (Dickerson, 1906; Harding, 1997)

Key Behaviors diurnal nocturnal crepuscular motile sedentary hibernation solitary
How do they communicate with each other?
American toads have one of the most notable calls of all toads. They give off long trill sounds that each last between 4 and 20 seconds. American toads use this call as a way to attract females for breeding. Their calls become frantic, loud, and constant during mating season. Many young males continue to call late into the summer. When they call, their throats puff out like large, inflatable balloons.

American toads also use body postures, touch, and chemical cues for communicating.

Communication Channels visual tactile acoustic chemical
Other Communication Modes choruses
Perception Channels visual tactile acoustic chemical
What do they eat?
Adult American toads are carnivores, but toad tadpoles are considered herbivores, because they graze on aquatic vegetation (algae).

Adult American toads are generalists. They eat a wide variety of insects and other invertebrates, including snails, beetles, slugs, and earthworms. Unlike most toads, who wait for prey to come along and pounce on it, American toads can shoot out their sticky tongues to catch prey. They also may use their front legs in order to eat larger food. They grasp their food and push it into their mouths. One American toad can eat up to 1,000 insects every day.

Toads do not drink water but soak it in, absorbing moisture through their skin. (Harding, 1997; Le Clere, 2000; Lerner, June 13 1998)

Primary Diet carnivore eats non-insect arthropods herbivore algivore
Animal Foods insects terrestrial non-insect arthropods terrestrial worms
Plant Foods algae
What eats them and how do they avoid being eaten?
The main predators of American toads are snakes. One species, eastern hognose snakes, specializes on eating toads. Some snakes, such as garter snakes, are immune to the poisonous glands of American toads. When these toads are faced with a predator that is immune to their poison they will sometimes urinate on themselves to become a less attractive meal. They also inflate their bodies with air to make themselves more difficult for a snake to swallow.

Female toads prefer to lay their eggs in ponds without fish. The eggs they lay are countershaded: lighter on the bottom and darker on the top to blend in with the background when viewed from above or below.

Tadpoles avoid predators by swimming in very shallow water, and by swimming close together in schools during the day. They also have toxic chemicals in their skin that discourage some potential predators. Metamorphosed toads are cryptically colored, and are actively mainly at night, making it harder for predators to find them. (Dickerson, 1906; Harding, 1997; Le Clere, 2000)

These animal colors help protect them cryptic
Known Predators
diving beetles (Dytiscidae)
predaceous diving bugs (Belostomatidae)
garter snakes (Thamnophis)
hognose snakes (Heterodon)
hawks (Accipitridae)
herons (Ardeidae)
raccoons (Procyon lotor)
What roles do they have in the ecosystem?
American toads are responsible for controlling the populations of many kinds of insects. The number of insects they eat makes them a crucial part of controlling these populations. (Dickerson, 1906)

Do they cause problems?
There are no negative impacts of American toads on humans.

How do they interact with us?
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 eventually prove useful in medical research. (Dickerson, 1906)

Ways that people benefit from these animals: research and education controls pest population
Are they endangered?
American toads have no special conservation status, as they are still common in most of their range. Some populations have declined in recent years, possibly due to pollution.

IUCN Red List
No special status
US Migratory Bird Act
No special status
US Federal List
No special status
CITES
No special status
State of Michigan List
No special status
Some more information...
American toads are the most widespread toad species in North America.

There are two subspecies of American toads, eastern and dwarf. Dwarf American toads live mainly in the west, eastern American toads live in the eastern portions of the range.

Contrary to folk-belief, you will not get warts if you touch a toad. However, the defensive chemicals in toad skin are toxic to humans, so its important to wash one's hands carefully after handling one.

Contributors
Allison Poor (editor), University of Michigan-Ann Arbor.

Stacey Grossman (author), Fresno City College, Carl Johansson (editor), Fresno City College.

References

  1. "Ohio History Center" (On-line). Accessed Sept. 20,2001 at http://www.ohiohistorycentral.org/ohc/nature/animals/reptile/americantoad.shtml.

Dickerson, M. 1906. The Frog. NY: Doubleday, Page and Company.

Harding, J. 1997. Amphibians and Reptiles of the Great Lakes Region. Ann Arbor, Michigan, USA: The University of Michigan Press.

King, R., M. Oldham, W. Weller, D. Wynn. 1997. Historic and current amphibian and reptile distributions in the island region of western Lake Erie. American Midland Naturalist, 138 (1): 153-173.

Le Clere, J. 2000. "American Toad" (On-line). Accessed Sept. 20,2001 at http://herpnet.net/Iowa-Herpetology/amphibians/frogs_toads/american_toad.html.

Lerner, J. June 13 1998. Growing a Garden of Wildly Delights. The Washington Post: G 16.

Matson, T. 2002. "An Introduction to the Natural History of the Frogs and Toads of Ohio" (On-line). Accessed Sept. 20,2001 at http://www.cmnh.org/collections/vertzoo/frogs/americanus.html.

Milius, S. 1998. Fatal skin fungus found in U.S. frogs. Science News, 154(1): 7.

Oliver, J. 1955. The National History of North American Amphibians and Reptiles. Princeton: D. Van Nostrand Company. Inc..

Rakestraw, J. 1998. Turning Over Rocks. Country Journal, 25 (3): 52-56.

Withgott, J. 2001. Feeling The Burn. Natural History, 110(6): 38-45.

here is a Link where you can get pics and sounds of American Toads:

http://www.biokids.umich.edu/critters/Anaxyrus_americanus/

Posted on May 27, 2015 19:09 by thespy1602 thespy1602 | 0 comments | Leave a comment

WIKI: AMERICAN TOADS

American toad
From Wikipedia, the free encyclopedia
American toad
American toad - Bufo americanus - 3.JPG
Specimen from Fairfax, Virginia
Conservation status

Least Concern (IUCN 3.1)[1]
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Amphibia
Order: Anura
Family: Bufonidae
Genus: Anaxyrus
Species: A. americanus
Binomial name
Anaxyrus americanus
Holbrook, 1836
Subspecies
A. a. americanus
A. a. charlesmithi
A. a. copei
B americanus range23.png
Range of A. americanus
Synonyms
Anaxyrus americanus[2]

The American toad (Anaxyrus americanus) is a common species of toad found throughout the eastern United States and Canada. 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). A new taxonomy places this species in the genus Anaxyrus instead of Bufo.[2][3]

Contents [hide]
1 Tadpoles
2 Biogeography
3 Subspecies
3.1 Eastern American toad
3.2 Dwarf American toad
3.3 Hudson Bay toad
4 Gallery
5 See also
6 References
7 External links
Tadpoles[edit]
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. Studies have shown that they have a mutualistic relationship with Chlorogonium alga, which makes tadpoles develop faster than normal.[citation needed]

Tadpoles have several mechanisms to reduce predation .[4] They avoid predators by swimming in very shallow water, 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.[5]

Biogeography[edit]
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.[6]

Subspecies[edit]
Races tend to hybridize with Anaxyrus woodhousii in their overlapping ranges.

Eastern American toad[edit]

Eastern American Toad in Ohio.

Detail of parotoid glands
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);[7] record 11.1 centimetres (4.4 in).[8] The color and pattern is somewhat variable. Skin color can change depending on humidity, stress, and temperature. Color changes range from yellow to brown to black. 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,[8] 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, 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 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 have any patterning on them.

Other species which 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. In the eastern American toad these crests almost never touch the parotoid glands, which secrete bufotoxin, a poisonous substance. The poison the toad excretes is mild in comparison to other poisonous toads and frogs, but it can irritate human skin[9] 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[8] 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. Adult toads are mostly nocturnal, although juveniles are often abroad by day. These toads 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.[5] Their diet includes crickets, mealworms, earthworms, ants, spiders, slugs, centipedes, moths, and other small invertebrates.

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.

Dwarf American toad[edit]
Wikispecies has information related to: Anaxyrus americanus charlesmithi
The dwarf American toad (B. a. charlesmithi), is a smaller version of the American toad which reaches lengths of about 6 cm (2½ inches) and 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. This subspecies of the American toad has been seen in the northern parts of Ontario were there are a few isolated populations. Interbreeding with the normal and eastern American toads caused this subspecies to lose the red coloring on their backs. 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.

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

Here is a link where you can get pictures of american toads:http://en.wikipedia.org/wiki/American_toad

Posted on May 27, 2015 19:06 by thespy1602 thespy1602 | 0 comments | Leave a comment

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