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Amphibians

desert bullfrog

Peterson Field Guides: Western Reptiles and Amphibians. Third edition. Robert C. Stebbins. 2003.

Amargosa Toad (Bufo nelsoni) are found exclusively in a 10-mile stretch of the Amargosa River and upland springs of Nevada. Amargosa toads may live up to 12 years in the wild. They are most active at night, and spend the days sheltered in burrows or dense vegetation. They thrive off of a diet of insects including spiders, and scorpions. 

Not much is known about their behaviors. Due to loss of habitat from degradation, pollution, and water diversion the Amargosa Toad is listed as a species of special concern by the IUCN, and classified as a protected amphibian by the Nevada Board of Wildlife Commissioners. 

https://www.fws.gov/nevada/nv_species/amargosa_toad.html
https://www.fws.gov/nevada/nv_species/documents/amargosa_toad/cca_amargosa_toad.pdf

Relict leopard frog (Rana onca) was thought to have gone extinct in 1950, until populations were discovered in Nevada in the 1990’s. Little is known about the distribution and habits of this elusive frog. They are believed to inhabit year-round streams, springs, and shorelines throughout Nevada. They have been found in Lake Mead and along the Muddy River in Nevada and Arizona. They may have once inhabited the Colorado River as well. 

The Relict leopard frog is struggling to survive due to loss of habitat from dams, agriculture, pollution, and water development projects. The spread of bullfrogs, crayfish, predatory fish, and a fungal disease known as chytridiomycosis are also threatening to outcompete the native species. The Relict leopard frog is federally listed as a species of special concern by the IUCN, and a candidate for listing as an endangered species.

https://www.fws.gov/nevada/protected_species/amphibians/species/relict_leopard_frog.html
https://www.nps.gov/para/learn/nature/relict-leopard-frog.htm

American bullfrog (Lithobates catesbeianus) is the largest frog found in the United States. It is native to Central and Eastern United States, but was introduced into the Western states in the 1900’s through trout stocking, as a food source, and poorly planned pest control efforts. 

American bullfrogs are found in warm aquatic marshes, ponds, lakes, or streams. They are said to eat anything that fits in their mouths, including snakes, insects, birds, frogs, tadpoles, and even their own young. It takes between 2 to 3 years for an egg to metamorphose and grow from egg to tadpole to fully grown adult.  

In the areas where bullfrogs have been introduced they have few natural predators, and often prey on and outcompetes native species. Frogs native to the West lay between 2,000 to 5,000 eggs, while a female American bullfrog can lay up to 20,000 eggs at a time. Because of their high reproduction rates and lack of natural predators they are on the invasive species list in many different states including Nevada, California, and Arizona. 

https://www.invasivespeciesinfo.gov/profile/bullfrog
https://seagrant.oregonstate.edu/sites/seagrant.oregonstate.edu/files/bf-species-guide.pdf
https://wildlife.ca.gov/Conservation/Invasives/Species/Bullfrog
https://nas.er.usgs.gov/queries/FactSheet.aspx?SpeciesID=71

Arizona toad (Bufo microscaphus) is a small toad which inhabits riparian areas throughout central Arizona, New Mexico, along the Colorado river, and where Arizona, Nevada, and Utah meet. 

There is little known about the behaviors or eating habits of the Arizona toad. They are noturnal, and spend most of their days in sandy underground burrows. It is believed they reach mating age between 2 to 3 years old. They do not migrate, so it’s presumed they hibernate from September to February or March. Once the conditions are right, in spring to early summer, they will mate and lay an average of 4,500 eggs. 

Arizona toad populations are threatened by loss and degradation of habitat due to damming and other human activities. In areas of the Beaver Dam wash and Virgin river a new hybrid species has been observed. It appears the Arizona toad has been reproducing with Woodhouse toads. They are currently listed as a species of least concern by the IUCN.

https://www.californiaherps.com/frogs/pages/a.microscaphus.html
https://amphibiaweb.org/cgi/amphib_query?where-genus=Anaxyrus&where-species=microscaphus

Woodhouse’s toads (Bufo woodhousii) have adapted to live in many different environments. They have been found thriving in Washington, Oregon, California, Nevada, Idaho, Montana, North and South Dakota, Utah, Colorado,Nebraska, Kansas, Oklahoma, Texas, New Mexico, and Arizona to Mexico. 

Hybridization between Woodhouse’s toads has been documented in a wide variety of riparian habitats across the United States. They will mate with many other species of toads including, Sonoran Desert toads (Balvarius) and Great Plains toads (Bcognatus), American toads (Bamericanus), Arizona toads, red-spotted toads, and many others. 

Feeding off of a variety of insects including scorpions, spiders, ants, larvea, and bees. The Woodhouse’s toad reaches sexually maturity between 1 to 2 years old. The female can lay over 28,000 eggs per clutch. The Woodhouse toad is one of the only native species that thrives alongside the invasive bullfrog. They are listed as a species of least concern by the IUCN.

https://amphibiaweb.org/cgi/amphib_query?where-genus=Anaxyrus&where-species=woodhousii
https://www.reptilesofaz.org/Turtle-Amphibs-Subpages/h-a-woodhousii.html

Great Basin Spadefoot Toad (Spea intermontana) is found primarily in sagebrush and semi-desert shrublands throughout Western North America, including British Columbia, Canada, Washington, Oregon, California, Nevada, Utah, and parts of Idaho, Colorado, and Wyoming. 

Mainly living on land, their diet consists largely of ants and beetles. They must migrate from dirt burrows to rain filled pools, streams or springs to mate. The migration typically coincides with spring and summer rains. Females lay between 300 to 800 eggs per clutch. It is estimated that they reach sexually maturity between 1 to 2 years old. Although their life span is not known for sure, it is estimated the Great Basin Spadefoot Toad may survive 11 to 13 years in the wild.

The Great Basin Spadefoot Toad populations thrive where conditions are suitable, and they are listed as a species of least concern by the IUCN. However numbers have declined in areas where habitat loss and degradation has occurred, and they are listed as a species of special concern in Colorado.

https://amphibiaweb.org/species/5280

Tiger salamander (Ambystoma tigrinum) is found in many different habitats throughout North America. Although populations are steady in many regions, Tiger salamanders have seen dramatic losses over the last 40 years. During the 1980’s and early 1990’s populations of Tiger salamander were believed to have dropped by up to 65% by habitat degradation caused by agricultural pesticides.

Adult Tiger Salamanders inhabit a wide variety of environments, and can be either aquatic or terrestrial. Those that live on land use their front limbs to burrow or utilize abandoned burrows, and spend much of their time underground to remain moist. Those that live in water require fishless ponds and permanent bodies of water.

They feed off a variety of small invertebrates, from insect larvae to field mice. They may live 16 to 25 years in the wild.  They make short migrations to breeding sites where hundreds of salamanders may gather. Females lay a wide range of eggs anywhere from 38 to 7,631 have been observed in a clutch. Dependent on water temperature eggs will hatch between 6.5 to 21 days. 

Tiger salamanders are sensitive to PH changes, and are currently listed as an Endangered Species in Delaware, New York, New Jersey, and Maryland. They are also protected in Arizona, and listed as a Species of Special Concern in North and South Carolina. They are listed as a species of Least Concern by the IUCN.  

https://amphibiaweb.org/cgi/amphib_query?where-genus=Ambystoma&where-species=tigrinum&account=lannoo

Red-spotted toad (Bufo punctatus) is a small toad found in freshwater riparian areas throughout South Western states, and Mexico. Adults grow between 1.5 to 3 inches long, eating a wide variety of insects and invertebrates. They reach sexually maturity between 3 to 4  years.

The Red-spotted toad is most active at night. It remains underground or resting at the edge of pools during the day. They reproduce externally between March to September. The female lays up to 5,000 eggs at a time in water, and the male fertilizes them shortly afterwards. The Red-spotted toad is the only toad in North America known to lay eggs separately in this way. Most toads lay eggs in a sticky string where they cling together. The eggs hatch within 72 hours in water temperatures between 72° F and 96° F (14° C and 35° C)

Red-spotted toads are active when average temperatures reach 65° F, they are presumed to hibernate in burrows during the winter months. They have been found to mate and hybridize with other toads including the Woodhouse’s and California Toad. They are considered a native species in California, and are being monitored but they are not listed currently listed by the IUCN or protected.

https://www.californiaherps.com/frogs/pages/a.punctatus.html#description
https://eol.org/pages/332429

Great Plains Toad (Anaxyrus cognatus) is found in grasslands, desert-scrub, and riparian areas throughout the Great Plains, and Western United States. Their range extends into Canada, and Mexico.

They are excellent diggers and may create new burrows every 1 to 6 days during the active seasons. They are most active at night, and spend most of their days in burrows. It is believed they spend up to 77% of the year underground, and emerge to breed during spring rains. Once they reach breeding age, between 2 to 5 years old, the Great Plains Toad will make short migrations, up to 1,300 meters, from their wintering burrows to a water source. The amount of eggs laid per clutch varies greatly depending on the size of the female. However, she can lay multiple clutches each breeding season. 

Great Plains Toads survive on a variety of insects, and small invertebrates. Studies indicate they may live 10 years or more in the wild. It is difficult to monitor the range and population of these animals because of the amount of time they spend underground. The Great Plains Toad is currently listed as a species of Least Concern by the IUCN, and receives no federal protections. 

https://www.itis.gov/servlet/SingleRpt/SingleRpt?search_topic=TSN&search_value=773516#null
https://amphibiaweb.org/species/145
https://amphibiaweb.org/cgi/amphib_query?where-genus=Anaxyrus&where-species=cognatus&account=lannoo

Pacific treefrog (Pseudacris regilla) is a very small frog native to the Mojave river system. It has adapted to a variety of habitats and has been found thriving in forests, grasslands, desert washes, ponds, and urban areas. They grow to be ¼ inch to 2 inches long.

The Pacific treefrog can quickly change colors in response to its environment. Typically from brown to green or vice versa to avoid predators.They are mostly active at night, but during the breeding season will also feed during the day. They eat a variety of invertebrates, and mostly flying insects. 

They reach breeding age within their first year, and will seek water to reproduce. Females lay between 400 to 750 eggs each season in irregular clusters of 10 to 80 eggs each. Once the male fertilizes the eggs externally, the adults leave the water. The eggs hatch within 2 to 3 weeks, and are quite resilient against UV rays and freezing temperatures. The Pacific treefrog is not currently listed or protected.  

https://www.californiaherps.com/frogs/pages/p.regilla.html
https://www.nps.gov/moja/learn/nature/amphibians.htm

California Treefrog (Pseudacris cadaverina) is a native species found throughout the Mojave desert. Growing to be just 1 to 2 inches long, they are found in riparian areas surrounding the Santa Monica Mountains, Joshua Tree National Park, and Baja California.

Mostly active at night they feed on a variety of insects and invertebrates including spiders and centipedes. They don’t spend much of their time in water outside of breeding season. The California Treefrog reaches sexual maturity at two years old. Mating and egg-laying occur in the spring and fall. Females lay between 400 to 750 eggs singly, but they tend to stick together in clusters of 10 to 80. Males fertilize the eggs externally. 

California tree frogs and Pacific tree frogs inhabit the same environments, so breeding and hybridization is quite probable. There have been no declines in populations or concerns, so this species is not listed or protected.

https://www.nps.gov/samo/learn/nature/californiatreefrog.htm
https://www.nps.gov/moja/learn/nature/amphibians.htm
https://www.dri.edu/images/stories/conferences_and_workshops/spring-fed-wetlands/spring-fed-wetlands-bradford.pdf
https://ovlc.org/baja-california-treefrog/