The Arizona toad (''Anaxyrus microscaphus'') is a
species
In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...
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 ...
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 ...
. It is
endemic
Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found else ...
to the south-western United States, where its natural
habitat
In ecology, the term habitat summarises the array of resources, physical and biotic factors that are present in an area, such as to support the survival and reproduction of a particular species. A species habitat can be seen as the physical ...
s are temperate lowland forests, rivers and streams, swamps, freshwater marshes, freshwater springs, ponds, open excavations, irrigated land, and seasonally flooded agricultural land.
Taxonomy
The Arizona toad was first described by the American
herpetologist
Herpetology (from Greek ἑρπετόν ''herpetón'', meaning "reptile" or "creeping animal") is the branch of zoology concerned with the study of amphibians (including frogs, toads, salamanders, newts, and caecilians ( gymnophiona)) and rep ...
Edward Drinker Cope in 1867. He named it ''Bufo microscaphus'' and the type locality was
Fort Mohave, Arizona
Fort Mohave is an unincorporated community and CDP in Mohave County, Arizona, United States. It is named for a nearby fort that was used during the Mohave War. As of the 2020 census, the population of Fort Mohave was 16,190, up from 14,364 in 2 ...
. It was commonly known as the southwestern toad and for many years, three subspecies were recognized, ''B. m. microscaphus'', ''B. m. californicus'' and ''B. m. mexicanus''. In 1998, the American herpetologist A. W. E. Gergus raised all three to full species status on the basis of
allozyme evidence,
allopatry
Allopatric speciation () – also referred to as geographic speciation, vicariant speciation, or its earlier name the dumbbell model – is a mode of speciation that occurs when biological populations become geographically isolated from ...
and
morphology
Morphology, from the Greek and meaning "study of shape", may refer to:
Disciplines
* Morphology (archaeology), study of the shapes or forms of artifacts
* Morphology (astronomy), study of the shape of astronomical objects such as nebulae, galaxies ...
.
[ The large genus '']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 t ...
'' was split by Frost et al. in 2006, with the North American species being included in the genus
Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...
''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
In biology, a subgenus (plural: subgenera) is a taxonomic rank directly below ...
''.[
]
Description
The Arizona toad grows to a snout-to-vent length of . The dorsal colour is variable but is often gray or beige with reddish-brown warts. 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 collectiv ...
s are oval and widely separated and there is often a pale stripe or patch on the head or spine. Juveniles are often salmon-coloured or greenish-brown.
Distribution and habitat
This species' range is continuous along the Virgin River
The Virgin River is a tributary of the Colorado River in the U.S. states of Utah, Nevada, and Arizona. The river is about long.Calculated with Google Maps and Google Earth It was designated Utah's first wild and scenic river in 2009, during the ...
and its tributaries in southwestern Utah
Utah ( , ) is a state in the Mountain West subregion of the Western United States. Utah is a landlocked U.S. state bordered to its east by Colorado, to its northeast by Wyoming, to its north by Idaho, to its south by Arizona, and to it ...
, and southern Nevada
Nevada ( ; ) is a state in the Western region of the United States. It is bordered by Oregon to the northwest, Idaho to the northeast, California to the west, Arizona to the southeast, and Utah to the east. Nevada is the 7th-most extensive, ...
, and in locations across Arizona
Arizona ( ; nv, Hoozdo Hahoodzo ; ood, Alĭ ṣonak ) is a state in the Southwestern United States. It is the 6th largest and the 14th most populous of the 50 states. Its capital and largest city is Phoenix. Arizona is part of the Fou ...
and western New Mexico
)
, population_demonym = New Mexican ( es, Neomexicano, Neomejicano, Nuevo Mexicano)
, seat = Santa Fe
, LargestCity = Albuquerque
, LargestMetro = Tiguex
, OfficialLang = None
, Languages = English, Spanish ( New Mexican), Navajo, Ke ...
. It is a protected species in Utah, Nevada and Arizona. Protected populations occur in the Virgin River and its tributaries in Zion National Park
Zion National Park is an American national park located in southwestern Utah near the town of Springdale. Located at the junction of the Colorado Plateau, Great Basin, and Mojave Desert regions, the park has a unique geography and a variety of ...
. The toads are usually found in sandy areas within about of streams, often in locations with flood channels and dense clumps of willow, or on nearby sandy terraces with live oaks and cottonwoods. In Arizona and New Mexico they sometimes occur at higher altitudes, up to about in forested areas in riparian corridors during rainy periods in summer. They also move into irrigated fields after the breeding season is over, and are found around reservoirs, ponds and other impounded areas.
Behavior
Breeding takes place in backwaters, the edges of streams and side-pools. Trees and shrubs growing at the streamside include Fremont's cottonwood (''Populus fremontii''), willow
Willows, also called sallows and osiers, from the genus ''Salix'', comprise around 400 speciesMabberley, D.J. 1997. The Plant Book, Cambridge University Press #2: Cambridge. of typically deciduous trees and shrubs, found primarily on moist so ...
s (''Salix'' spp.), and seep willows (''Baccharis salicifolia''). Breeding starts in late February in Arizona but does not commence at higher altitudes in Arizona and in Utah until several weeks later. The male's call is a trill lasting about six seconds. Calling males are often outnumbered by satellite males which opportunistically mate with approaching females. 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 ...
takes place and a clutch of about 4,500 eggs is laid in shallow water. The eggs take three to six days to hatch and the development period of the tadpoles before metamorphosis depends largely on the water temperature. The tadpoles probably feed on algae and other organisms attached to underwater surfaces but the diet of adults has not been studied. The toads are nocturnal, spending the day in sandy burrows. They enter a state of torpor and remain underground from about September to February. They may live for four or five years and the main cause of mortality is probably predation
Predation is a biological interaction where one organism, the predator, kills and eats another organism, its prey. It is one of a family of common feeding behaviours that includes parasitism and micropredation (which usually do not kill th ...
, with raccoon
The raccoon ( or , ''Procyon lotor''), sometimes called the common raccoon to distinguish it from other species, is a mammal native to North America. It is the largest of the procyonid family, having a body length of , and a body weight of ...
s (''Procyon lotor''), a medium-sized plover the killdeer
The killdeer (''Charadrius vociferus'') is a large plover found in the Americas. It was described and given its current scientific name in 1758 by Carl Linnaeus in the 10th edition of his ''Systema Naturae''. Three subspecies are described. Th ...
(''Charadrius vociferus''), and the wandering garter snake (''Thamnophis elegans vagrans'') feeding on the toads.[
]
Status
The population size of the Arizona toad is believed to be decreasing at a slow rate, probably due to human disturbance of their habitat, and in some localities, such as central Arizona, they are being replaced by 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 overl ...
(''Anaxyrus woodhousii''). One threat faced by the Arizona toad is hybridization between these two species. They occupy similar habitat but theoretically should not hybridise because they breed at different seasons. However the male Arizona toad has occasionally been observed to mate with the female Woodhouse's toad. The Arizona toad has also been known to attempt mating with the Great Basin spadefoot toad (''Spea intermontana''), the Great Plains toad (''Bufo cognatus''), the red-spotted toad (''Bufo punctatus''), the canyon tree frog (''Hyla arenicolor''), the American bullfrog (''Lithobates catesbeiana''), and the lowland leopard frog
The lowland leopard frog (''Lithobates yavapaiensis'') is a species of frog in the family True frog, Ranidae that is found in Mexico and the United States.
Its natural habitats are temperate forests, rivers, intermittent rivers, freshwater lakes ...
(''Lithobates yavapaiensis'').[ The Arizona toad has a wide range and is assumed to have a large total population. It is an adaptable species and able to tolerate some degree of habitat modification so the ]International Union for Conservation of Nature
The International Union for Conservation of Nature (IUCN; officially International Union for Conservation of Nature and Natural Resources) is an international organization working in the field of nature conservation and sustainable use of nat ...
has assessed it as being of "least concern
A least-concern species is a species that has been categorized by the International Union for Conservation of Nature (IUCN) as evaluated as not being a focus of species conservation because the specific species is still plentiful in the wild. T ...
".
References
*
{{Taxonbar, from=Q2237121
Anaxyrus
Amphibians of the United States
Endemic fauna of the United States
Amphibians described in 1867
Taxa named by Edward Drinker Cope
Taxonomy articles created by Polbot