Arroyo toad | |
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Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Class: | Amphibia |
Order: | Anura |
Family: | Bufonidae |
Genus: | Anaxyrus |
Species: | A. californicus |
Binomial name | |
Anaxyrus californicus (Camp, 1915) | |
Synonyms | |
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The arroyo toad (Anaxyrus californicus) is a species of true toads in the family Bufonidae, endemic to California, U.S. and Baja California state, Mexico. [1] [2] It is currently classified as an Endangered species on the IUCN Red List of Threatened Species because of habitat destruction. [1] The arroyo toad is at the intersection of ecological significance and conservation concern.
The arroyo toad is a stocky, blunt-nosed, warty-skinned species of toad, 5 to 7.5 cm (2.0 to 3.0 in) long. It has horizontal pupils, and is greenish, grey or salmon on the dorsum with a light-colored stripe across the head and eyelids. It has light sacral and mid-dorsal patches, large, oval and widely separated parotoid glands, and weak or absent cranial crests. The juvenile of this species are ashy-white, olive or salmon on the dorsal side, with or without black spotting. It has red-tipped tubercles on its back. [3]
The arroyo toad prefers sandy or cobbly washes with swift currents and associated upland and riparian habitats, in Southern California from Santa Barbara County south into northwestern Baja California. The arroyo toad serves as an important indicator species in Southern California ecosystems. Its presence or absence can signal the overall health of its habitat. An arroyo, in the desert called a wash, is a predominantly dry creek or river bed. It fills and flows after sufficient rain, but only temporarily during specific seasons. The arroyo toad inhabits these areas alongside creeks and rivers with shallow pebble-like rocks near sandy terrains. Adults take refuge into the sandy soil for protection and shelter and for deposition of eggs. Areas with very little to no vegetation are the primary target. [1] [3]
The arroyo toad is nocturnal, spending most of the day underground with exception to mating season. Recent research has shown that the arroyo toad is highly sensitive to changes in water quality, making it a vital species for environmental monitoring. The arroyo toad has a unique mating call that distinguishes it from other toads in its range, contributing to its identification and study. During the mating season, the Arroyo Toad may be found during the day along the shallows of a pond. It travels by quickly hopping, as opposed to walking or striding. When hunting for food the toad lunges towards the targets, usually ants, and extends its large sticky tongue to trap and consume them. [3]
During the dry season the arroyo toad goes into a state of hibernation called aestivation to prevent dehydration. This dormant state normally takes place within the soil or clay-like sand and is from August to January.[ citation needed ]
The breeding season of the arroyo toad revolves around the months of late winter and early spring after seasonal rains. The male toad will choose a spot near a river or water bank where he will make mating calls to attract a female toad. They mate in an amplexus position, and the female toad returns to the location to lay her eggs by the water. The eggs are laid in a two-row formation with an average of 4,700 eggs. The placement of the eggs by the water is very crucial due to the water flow: if some of the eggs are too far from hydration they will dry up and die; eggs can also drop into the depth of the water and be eaten by predators. The eggs that survive hatch in between four and six days. [3]
Once the eggs hatch, the larvae feed on microbes found in the sand by the water where they hatch. The arroyo toad also plays a role in nutrient cycling within its habitat. Its activities help enrich the soil, which in turn supports plant growth. For the most part, young arroyo toads feed on ants and other small insects. [3] When they grow their diet changes to include small beetles. The diet of an adult toad usually consists of caterpillars, moths, crickets, snails, and in some instances eggs and larvae of other Arroyo toads. [4]
The toad defends itself with a toxin found on its skin. The toxin is released from the parotoid glands which can be identified as pale spots found towards the head. The main component found in the venom is called bufotoxin. All of the venom found on the toad's skin is enough to cause serious symptoms or even death in the attacker. Although some natural predators have built an immunity and regularly feed on the toads, their toxin should not be underestimated. [5]
If a human comes in contact with the toad's skin symptoms include: serious irritation and pain to the throat, eyes, nose, and mouth, cardiovascular and respiratory systems, seizures and paralysis, vomiting, hallucinations or even death. There is no anti-venom and treatment varies based on the symptoms exhibited. [5]
Another method of defense is hiding in vegetation or underwater from attackers. [5]
The arroyo toad is fairly cryptic, but often vulnerable to a variety of predators. Eggs and larvae are susceptible to being preyed on by fish, other species of frogs (not excluding adult forms of the Arroyo toad), birds, snakes, and insects that inhabit the waters where the eggs and larvae are developing. [5]
Adult arroyo toads are also vulnerable to predators such as American Bullfrogs and garter snakes. Although they may escape, they have a high likeliness of dying from wounds caused by their attackers. The American Bullfrog has a tendency to prey on males during their mating calls, and will attack toads while they are in amplex thereby preventing reproduction rates in the population. This has a great influence on the decrease in the species population number. [5]
The total estimated breeding population is less than 3,000 individuals. In 1994 when the species was listed, only six of the 22 extant populations south of Ventura were known to contain more than a dozen adults. It has been extirpated from an estimated 75% of its former range in the U.S. [1]
The most important threats to the arroyo toad stem from human activities. [6] [7] These activities include encroachment by agriculture, construction of roads, off-road vehicle use, grazing by livestock and mining. All can result in substantial habitat destruction and/or alteration of river hydrology. [1] Other smaller threats are due to introduced non−native predators such as bullfrogs and predatory fish, non−native invasive plants, drought, wildfire and wildfire suppression, unseasonal water releases from dams, and light and noise pollution from adjacent developments. [1]
The arroyo toad has been the subject of litigation related to its conservation status. Conservation initiatives are in place to mitigate the decline of the arroyo toad. These include habitat restoration projects and community education programs. In 2000, developer Rancher Viejo, which wished to build on a site that the toads used as a habitat, sued the Secretary of the Interior over whether the department was constitutionally authorized to apply the Endangered Species Act to prevent the development in order to protect a species that never crossed state lines. The developer's challenge to the law failed, but in his dissent to the ruling then-Judge and later-Chief Justice John Roberts famously expressed his puzzlement that "regulating the taking of a hapless toad that, for reasons of his own, lives its entire life in California constitutes regulating 'commerce...among the several states'." [8]
On March 27, 2014, the Department of Fish and Wildlife recommended the arroyo toad's status be downgraded from Endangered to Threatened. The agency stated that the arroyo toad still faces "significant threats", in particular operation of dams and water diversions, urban development, introduced predator species, and drought. However, they felt that conditions had improved, saying, "The overall magnitude of threats impacting the arroyo toad has decreased since the time of listing, due in part to implementation of conservation and management actions." [6]
The Colorado River toad, also known as the Sonoran Desert toad, is a toad species found in northwestern Mexico and the southwestern United States. It is well known for its ability to exude toxins from glands within its skin that have psychoactive properties.
The black toad, also known as the Inyo toad or Deep Springs toad, is a true toad that lives only in scattered oases in the Deep Springs Valley of Inyo County, California. In fact, its original scientific name, Bufo exsul, means "exiled toad", which refers to its species' isolation in a tiny spot in the high desert wilderness of the Californian Great Basin.
The American toad is a common species of toad found throughout Canada and the eastern United States. It is divided into three subspecies: the eastern American toad, the dwarf American toad and the rare Hudson Bay toad. Recent taxonomic treatments place this species in the genus Anaxyrus instead of Bufo.
The California newt or orange-bellied newt, is a species of newt endemic to California, in the Western United States. Its adult length can range from 5 to 8 in. Its skin produces the potent toxin tetrodotoxin.
The Houston toad, formerly Bufo houstonensis, is an endangered species of amphibian that is endemic to Texas in the United States. This toad was discovered in the late 1940s and named in 1953. It was among the first amphibians added to the United States List of Endangered Native Fish and Wildlife and is currently protected by the Endangered Species Act of 1973 as an endangered species. The Houston toad was placed as "endangered" on the IUCN Red List of Threatened Species from 1986 to 2022, and has worsened to "critically endangered" since then, with fewer than 250 mature individuals believed to remain in the wild as of 2021. Their kind is threatened every day as they continue to suffer from a loss of habitat, extreme drought, and massive wildfires. Their typical life expectancy is at least 3 years but it may exceed this number.
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 Wyoming toad, also known commonly as Baxter's toad, is a species of toad in the family Bufonidae. The Wyoming toad is an extremely rare amphibian that exists only in captivity and within Mortenson Lake National Wildlife Refuge in Wyoming in the United States. The Wyoming toad was listed as an endangered species in 1984, and listed as extinct in the wild since 1991. As with black-footed ferrets at the Tom Thorne and Beth Williams Wildlife Research Center at Sybille in Wheatland, Wyoming, the effort to save the Wyoming toad has been a cooperative effort among state and federal agencies and private landowners. The Wyoming toad was common from the 1950s through the early 1970s, but its distribution was limited to the Laramie Basin in Albany County. The population crashed around 1975 and was extremely low by 1980. The Wyoming toad was federally listed as endangered in January 1984. To prevent extinction, a captive-breeding program began in 1989 at the Thorne Williams Unit that produced enough offspring in its first few years to supply seven zoos, and in 1998 the Saratoga National Fish Hatchery received captive-breeding stock. Nearly 46,000 offspring were produced at the Thorne Williams Unit from 1995 until 2006, when the remaining captive stock was moved to the Red Buttes Environmental Biology Laboratory south of Laramie, and then released back into the wild. Before the sharp declines occurred, this toad had been originally classified as Bufo hemiophrys baxteri, a subspecies of the Canadian toad, by Kenneth Raymond Porter in 1968.
The yellow-bellied toad belongs to the order Anura, the archaeobatrachial family Bombinatoridae, and the genus of fire-bellied toads. The toad is distributed mainly across western Europe as well as a handful of countries in eastern Europe. While the population of the toad is steadily decreasing over time, its numbers are not critical enough to be considered threatened or extinct. Conservation efforts in Germany are taking place to remedy the declining population before it is too late.
The boreal toad is the nominate subspecies of the western toad. They are commonly found in the Southern Rocky Mountains, and their population has recently been on the decline 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.
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.
Gastrophryne carolinensis, the eastern narrow-mouthed toad, is a species of microhylid frog. It is a relatively small, toad-like amphibian found in damp, shady habitats. The species is highly fossorial, and feeds primarily on ants. These North American microhylids are distinguished from true toads, and other anurans by their moist, smooth skin, their lack of eardrums or tympana, their distinguishable squat body shape, and the unique fold of skin superior to their eyes. It is found in the United States, from southern Maryland to the Florida Keys, west to Missouri and Texas. While not a true toad, it is so called because it is terrestrial.
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 Mission blue is a blue or lycaenid butterfly subspecies native to the San Francisco Bay Area of the United States. The butterfly has been declared as endangered by the US federal government. It is a subspecies of Boisduval's blue.
The giant garter snake is the largest species of garter snake. Relatively rare, it is a semi-aquatic snake with a limited distribution in the wetlands of central California.
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.
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 Amargosa toad is a species of toad in the family Bufonidae. It was at one time considered to be a subspecies of the western toad. It is threatened by habitat loss and is classified by the IUCN as being critically endangered.
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.
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California Department of Fish and Wildlife (2020). "Impact of Human Activities on the Arroyo Toad."
Davis, Laura (2017). "Acoustic Characteristics of the Arroyo Toad." Journal of Animal Behavior.
Green, Emily (2019). "Conservation Strategies for the Arroyo Toad." Conservation Biology.
Smith, Jane L. (2018). "The Ecological Importance of the Arroyo Toad in Southern California Ecosystems." Journal of Herpetology.
Williams, Sarah (2022). "Nutrient Cycling and the Arroyo Toad." Journal of Ecology.