The arroyo toad (''Anaxyrus californicus'') is a species of

true toad A true toad is any member of the family Bufonidae, in the order Anura (frogs and toads). This is the only family of anurans in which all members are known as toads, although some may be called frogs (such as harlequin frogs). The bufonids now ...

s in the family

Bufonidae {{Cat main, Toad This category contains both species commonly called toads, and the true toads from the family Bufonidae {{Cat main, Toad This category Category, plural categories, may refer to: Philosophy and general uses *Categorization, cat ...

, endemic to

California California is a state in the Western United States, located along the Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the most populous U.S. state and the 3rd largest by area. It is also the m ...

(U.S.) and

Baja California Baja California (; 'Lower California'), officially the Free and Sovereign State of Baja California ( es, Estado Libre y Soberano de Baja California), is a state in Mexico. It is the northernmost and westernmost of the 32 federal entities of Mex ...

state (México). It is currently classified as an Endangered species on the

IUCN Red List The International Union for Conservation of Nature (IUCN) Red List of Threatened Species, also known as the IUCN Red List or Red Data Book, founded in 1964, is the world's most comprehensive inventory of the global conservation status of biol ...

of Threatened Species because of

habitat destruction Habitat destruction (also termed habitat loss and habitat reduction) is the process by which a natural habitat becomes incapable of supporting its native species. The organisms that previously inhabited the site are displaced or dead, thereby ...

Description

The arroyo toad is a stocky, blunt-nosed, warty-skinned 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 scient ...

, 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 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 collectiv ...

s, 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.

Distribution and habitat

''Anaxyrus californicus'' prefers sandy or cobbly washes with swift currents and associated upland and

riparian A riparian zone or riparian area is the interface between land and a river or stream. Riparian is also the proper nomenclature for one of the terrestrial biomes of the Earth. Plant habitats and communities along the river margins and banks a ...

habitats, in

Southern California Southern California (commonly shortened to SoCal) is a geographic and cultural region that generally comprises the southern portion of the U.S. state of California. It includes the Los Angeles metropolitan area, the second most populous urban a ...

from

Santa Barbara County Santa Barbara County, California, officially the County of Santa Barbara, is located in Southern California. As of the 2020 census, the population was 448,229. The county seat is Santa Barbara, and the largest city is Santa Maria. Santa Barba ...

south into northwestern

. An arroyo, in the desert called a

wash WASH (or Watsan, WaSH) is an acronym that stands for "water, sanitation and hygiene". It is used widely by non-governmental organizations and aid agencies in developing countries. The purposes of providing access to WASH services include achievi ...

, 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.

Behavior

The arroyo toad is nocturnal, spending most of the day underground with exception to mating season. During the mating season 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. 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. Arroyo toad (23789477236)

Reproduction

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 Amplexus (Latin "embrace") is a type of mating behavior exhibited by some externally fertilizing species (chiefly amphibians and horseshoe crabs) in which a male grasps a female with his front legs as part of the mating process, and at the same ...

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.

Diet

Once the eggs hatch, the larvae feed on microbes found in the sand by the water where they hatch. For the most part, young arroyo toads feed on ants and other small insects. 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.

Defense mechanisms

''Anaxyrus californicus'' defends itself with a toxin found on its skin. The toxin is released from the

s which can be identified as pale spots found towards the head. The main component found in the venom is called

bufotoxin Bufotoxins are a family of toxic steroid lactones or substituted 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, and in some plants and ...

. 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. 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. Another method of defense is hiding in vegetation or underwater from attackers.

Predators

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. 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.

Conservation

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. The most important threats to the arroyo toad stem from human activities. These activities include encroachment by agriculture, construction of roads, off-road vehicle use, grazing by livestock and mining. All can result in substantial

and/or alteration of river hydrology. Other smaller threats are due to introduced non−native predators such as

bullfrog ''Bullfrog'' is a common English language term to refer to large, aggressive frogs, regardless of species. Examples of bullfrogs include: Frog species America * Helmeted water toad (''Calyptocephalella gayi''), endemic to Chile *American bullfr ...

s and predatory fish, non−native

invasive plant An invasive species otherwise known as an alien is an introduced organism that becomes overpopulated and harms its new environment. Although most introduced species are neutral or beneficial with respect to other species, invasive species adv ...

s, drought, wildfire and

wildfire suppression Wildfire suppression is a range of firefighting tactics used to suppress wildfires. Firefighting efforts in wild land areas require different techniques, equipment, and training from the more familiar structure fire fighting found in populated ...

, unseasonal water releases from dams, and light and noise pollution from adjacent developments. The arroyo toad has been the subject of litigation related to its conservation status. 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 John Glover Roberts Jr. (born January 27, 1955) is an American lawyer and jurist who has served as the 17th chief justice of the United States since 2005. Roberts has authored the majority opinion in several landmark cases, including '' Nat ...

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'." On March 27, 2014, the Department of Fish and Wildlife recommended the arroyo toad's status be downgraded from Endangered to

Threatened Threatened species are any species (including animals, plants and fungi) which are vulnerable to endangerment in the near future. Species that are threatened are sometimes characterised by the population dynamics measure of ''critical depensa ...

. 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."

References

External links

* * {{Taxonbar, from=Q28030852 Anaxyrus Amphibians of Mexico Amphibians of the United States Fauna of the California chaparral and woodlands Natural history of Baja California Natural history of the Peninsular Ranges Natural history of the Transverse Ranges Endangered fauna of California ~ Amphibians described in 1915 ESA endangered species Species endangered by habitat loss