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Pseudacris cadaverinaCalifornia Treefrog

By Selina Martinez

Geographic Range

California tree frogs, also known as California chorus frogs (Pseudacris cadaverina), are native to North American regions. They are found along the coastal parts of Southern California in the U.S. and Baja California Norte in Mexico (Stebbins and McGinnis, 2012). California tree frogs can be found in numerous counties in Southern California including: San Luis Obispo to Joshua Tree National Forest, San Diego, and Granite Mountain Preserves (Ervin, 2020). (Ervin, 2020; Stebbins and McGinnis, 2012)

Habitat

California tree frogs are found within the coastal sage and streams of Southern California and Baja, Mexico; these areas range from 0 to 2,290 m above sea level (Stebbins and McGinnis, 2012). Adult California tree frogs have been found to populate a wide range of habitats, such as canyon, desert, and coastal streams up into mountain stream channels. Although they prefer to live alone, they have been observed cohabiting streams with fish that eat invertebrates (Ervin, 2020).

During they day, California tree frogs often seek shelter in small voids of boulders near the waterline (Ervin, 2020). While these boulders are in direct sunlight, California tree frogs secrete a mucous film to prevent their epithelium layers from drying out via evaporation. They are not active year-round; however, this species undergoes aestivation during periods of extreme heat or cold (Alvarez and Contreras, 2016). As adults, California tree frogs do not spend a large amount of time in the water; however, during breeding season they have been observed sitting in clean rocky washes with calm pools (Ervin, 2020). Once their eggs are laid and hatched, juveniles remain in their breeding pools, in areas between small boulders and around the bases of annual plants. They live in their breeding pools until complete metamorphosis occurs (Ervin, 2020). (Alvarez and Contreras, 2016; Ervin, 2020; Stebbins and McGinnis, 2012)

  • Aquatic Biomes
  • lakes and ponds
  • rivers and streams
  • temporary pools
  • Range elevation
    0 to 2,290 m
    0.00 to ft

Physical Description

California tree frog tadpoles grow up to 3.7 cm long and have flattened bodies (Stebbins and McGinnis, 2012). They can be distinguished from sympatric Baja California tree frogs (Pseudacris hypochondriaca) by their eyes, which are located within the outlines of their heads. Alternatively, Baja California tree frogs have their eyes on the outer edges of their eyes (Ervin, 2020). Adult California tree frogs have snout-vent lengths (SVL) ranging from 2.5 to 5.1 cm long (Stebbins and McGinnis, 2012). Their toe pads are characterized as large in width and shortened, with webbing from medial to lateral toes. They have rough skin with a wide range of color patterns that consist of gray or light brown skin with small dark brown spots. The abdomens of California tree frogs appear white, with yellowish limbs and groins (Stebbins and McGinnis, 2012). Males can be distinguished from females by a dusky yellow color on their necks (Ervin, 2020). California tree frogs can be distinguished from Baja California tree frogs (Pseudacris hypochondriaca) by the lack of stripes through each eye (Stebbins and McGinnis, 2012). (Ervin, 2020; Stebbins and McGinnis, 2012)

  • Sexual Dimorphism
  • sexes colored or patterned differently
  • Range length
    2.5 to 5.1 cm
    0.98 to 2.01 in

Development

The breeding season of California tree frogs begins in early February, after winter rains decline. Mature males utilize mating calls to attract mature females into breeding ponds and other aquatic areas. Male mating calls are repeated sounds of quick, deep, and loud duck-like quacks (Cocroft, 1995). Mating and spawning season happens from February to early October (Stebbins and McGinnis, 2012). Clutch sizes are unknown; however, individual eggs are encased in a gelatinous adhesive envelope. Eggs are typically laid in single strands that end up merging into clumps (Ervin, 2020). The adhesive property of eggs allows for attachment to submerged leaves and debris surrounded by boulders and rocks, which are found in still or slow-moving pools of water (Ervin, 2020). The submersion of eggs allows for protection against harmful UV rays.

Once larvae hatch, complete metamorphosis in larvae can be seen after 40 to 75 days (Stebbins and McGinnis, 2012). In California, California tree frogs undergo metamorphosis from June through August (Ervin, 2020). Juvenile frogs commonly remain near their natal pools for a short period after metamorphosis; however, some immediately begin to move into the surrounding habitat. Juvenile California tree frogs reach sexual maturity at around two years old (Ervin, 2020). (Cocroft and Ryan, 1995; Ervin, 2020; Stebbins and McGinnis, 2012)

Reproduction

When mating, California tree frogs pair in inguinal amplexus. This means that males climb onto the backs of females and grip their hips tightly. Females deposit their eggs into breeding ponds for external fertilization by males (Ervin, 2020). The number of mates each sex has in one breeding season or life time is unknown.

  • Key Reproductive Features
  • gonochoric/gonochoristic/dioecious (sexes separate)
  • Average age at sexual or reproductive maturity (female)
    2 years
  • Average age at sexual or reproductive maturity (male)
    2 years

After spawning, both male and female tree frogs leave the breeding ponds, implying little-to-no parental care (Ervin, 2020).

  • Parental Investment
  • no parental involvement

Lifespan/Longevity

California tree frogs reach maturity at around 2 years of age. After this point, their longevity is unknown (Ervin, 2020). However, within the same genus, it is known that Pacific tree frogs (Pseudacris regilla) can live up to 8 years in captivity (Croft, 1994). (Cocroft, 1994; Ervin, 2020)

Behavior

California tree frogs are not seen often, due to their nocturnal tendencies (Stebbins and McGinnis, 2012). During spring and summer days, California tree frogs are known to seek shelter in the shaded crevices of rocks and boulders, along pools of water (Ervin, 2020). During the fall and winter, California tree frogs move to higher elevated crevices to avoid heavy rainfall drainage (Ervin, 2020).

Mature California tree frogs are rarely seen in the water unless they are breeding or avoiding predation. Even in these cases, they return back to land shortly after. California tree frogs undergo a state of torpor from December to March, as well as extreme hot or cold periods during the rest of the year (Ervin, 2020). Both adults and tadpoles have cryptic coloration to avoid predators (Stebbins and McGinnis, 2012).

Males utilize vocalizations not only for mating, but also as warning calls to intimidate competing males (Cocroft and Ryan, 1995). Males often show aggressive and territorial behaviors towards the same sex through combat and threatening vocalizations (Stebbins and McGinnis, 2012). (Cocroft and Ryan, 1995; Ervin, 2020; Stebbins and McGinnis, 2012)

Home Range

Little is known about the home range of California tree frogs.

Communication and Perception

California tree frogs utilize vocalization to communicate during mating and competition. During the breeding season, male California tree frogs use advertisement calls to attract females into breeding ponds. This mating call is a repeated pattern of fast, loud, low-pitched quacking sounds (Cocroft and Ryan, 1995). Mating calls sound different from the warning calls that males use to protect their territory. These warning calls have been characterized to have a greater intensity in pitch than mating calls (Ervin, 2020). It is common for Anurans (order Anura) to use binocular depth perception to locate and determine distances from their prey (Ewert, 2001). (Cocroft and Ryan, 1995; Ervin, 2020; Ewert, et al., 2001)

Food Habits

California tree frog tadpoles are known to be generalists, with a diet consisting of plant material, periphyton from algal mats, and organic detritus found in their natal ponds (Ervin, 2020). As adults, California tree frogs feed on a variety of invertebrate species including centipedes, spiders, grasshoppers, ants, beetles, moths, sow bugs, true bugs, and lacewings (Cunningham, 1964). Like all Anurans, California tree frogs use a specialized tongue and sticky saliva to catch and bring prey into their mouths. (Cunningham, 1964; Ervin, 2020)

  • Animal Foods
  • insects

Predation

In stream pools, California tree frogs are highly susceptible to predation by rainbow trout (Oncorhynchus mykiss) and aquatic two-striped garter snakes (Thamnophis hammondii) (Ervin, 2020). Two-striped garter snakes have also been observed eating adult tree frogs due to their shared geographic habitat range (Ervin, 2020). Adult California tree frogs are often preyed upon by invasive species such as green sunfish (Lepomis cyanellus) that were introduced to southern California drainage areas (Ervin, 2020).

Both California tree frog tadpoles and adults use cryptic coloration as an anti-predator mechanism. California tree frog larvae use variations of brown with gold spots to camouflage with the sand and substrates in their natal ponds (Stebbins and McGinnis, 2012). As adults, California tree frogs have dorsal color patterns that resemble rocks and boulders. California tree frogs remain extremely still when predators approach to avoid detection; however, they can rapidly jump into nearby streams if attacked while they are perching (Cunningham, 1964). (Cunningham, 1964; Ervin, 2020; Stebbins and McGinnis, 2012)

  • Anti-predator Adaptations
  • cryptic

Ecosystem Roles

California tree frogs play an important role in their ecosystem by controlling the populations of insects they consume. Tadpoles are a vital food source to rainbow trout (Oncorhynchus mykiss) and adults serve as food for two-striped garter snakes (Thamnophis hammondii).

California tree frogs have been observed to host parasites, such as larval chiggers (Trombiculidae) embedded in their skin. In addition, California tree frogs have been seen hosting numerous parasitic species of trematodes and two parasitic species of nematodes: (Rhabdias ranae) and Physaloptera sp. (Ervin, 2020). (Ervin, 2020)

Commensal/Parasitic Species
  • Trombiculidae

Economic Importance for Humans: Positive

California tree frogs act as natural pest control for human populations by maintaining insect populations.

  • Positive Impacts
  • controls pest population

Economic Importance for Humans: Negative

Since California tree frogs are not an invasive species and do not possess poison glands, they are not known to cause any harm to humans or their property.

Conservation Status

According to the IUCN Red List, California tree frogs are of least concern and have stable populations (Hammerson and Santos-Barrera, 2004). However, threats of urban and commercial development on their populations is still being investigated (Hammerson and Santos-Barrera, 2004). In addition, effects of the introduction of non-native predatory fish species on California tree frogs are still unknown (Ervin, 2020). (Ervin, 2020; Hammerson and Santos-Barrera, 2004)

Other Comments

Adult California tree frogs and Pacific tree frogs (Pseudacris regilla) have been reported to naturally hybridize to produce viable offspring (Stebbins and McGinnis, 2012). However, attempts to mate these two species in a lab setting has been unsuccessful, producing inviable offspring (Ervin, 2020). (Ervin, 2020; Stebbins and McGinnis, 2012)

Contributors

Selina Martinez (author), California State University, San Marcos, Tracey Brown (editor), California State University, San Marcos, Galen Burrell (editor), Special Projects.

Glossary

Neotropical

living in the southern part of the New World. In other words, Central and South America.

World Map

acoustic

uses sound to communicate

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

carnivore

an animal that mainly eats meat

chaparral

Found in coastal areas between 30 and 40 degrees latitude, in areas with a Mediterranean climate. Vegetation is dominated by stands of dense, spiny shrubs with tough (hard or waxy) evergreen leaves. May be maintained by periodic fire. In South America it includes the scrub ecotone between forest and paramo.

cryptic

having markings, coloration, shapes, or other features that cause an animal to be camouflaged in its natural environment; being difficult to see or otherwise detect.

ectothermic

animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature

forest

forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.

hibernation

the state that some animals enter during winter in which normal physiological processes are significantly reduced, thus lowering the animal's energy requirements. The act or condition of passing winter in a torpid or resting state, typically involving the abandonment of homoiothermy in mammals.

insectivore

An animal that eats mainly insects or spiders.

metamorphosis

A large change in the shape or structure of an animal that happens as the animal grows. In insects, "incomplete metamorphosis" is when young animals are similar to adults and change gradually into the adult form, and "complete metamorphosis" is when there is a profound change between larval and adult forms. Butterflies have complete metamorphosis, grasshoppers have incomplete metamorphosis.

motile

having the capacity to move from one place to another.

mountains

This terrestrial biome includes summits of high mountains, either without vegetation or covered by low, tundra-like vegetation.

native range

the area in which the animal is naturally found, the region in which it is endemic.

nocturnal

active during the night

phytoplankton

photosynthetic or plant constituent of plankton; mainly unicellular algae. (Compare to zooplankton.)

planktivore

an animal that mainly eats plankton

suburban

living in residential areas on the outskirts of large cities or towns.

temperate

that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).

terrestrial

Living on the ground.

territorial

defends an area within the home range, occupied by a single animals or group of animals of the same species and held through overt defense, display, or advertisement

visual

uses sight to communicate

References

Alvarez, C., H. Contreras. 2016. The effect of dehydration on the metabolic rate and locomotor performance of two species of tree frogs found in Southern California (Pseudacris regilla and P. cadaverina). FASEB JOURNAL, 30: 1.

Cocroft, R. 1994. A Cladistic Analysis of Chorus Frog Phylogeny (Hylidae: Pseudacris). Herpetologica, 50.4: 420-437. Accessed February 18, 2020 at https://www.jstor.org/stable/3892719.

Cocroft, R., M. Ryan. 1995. Patterns of advertisement call evolution in toads and chorus frogs. The Association for the Study of Animal Behaviour, 49/2: 283-303. Accessed February 18, 2020 at https://doi.org/10.1006/anbe.1995.0043.

Cunningham, J. 1964. Observations on the ecology of the canyon tree frog, Hyla californiae. Herpetologica, 20: 55-61.

Ervin, E. 2020. "Hyliola cadaverina" (On-line). AmphibiaWeb. Accessed March 10, 2020 at http://amphibiaweb.org.

Ewert, J., H. Buxbaum-Conradi, F. Dreisvogt, M. Glagow, C. Merkel-Harff, A. Rottgen, E. Schurg-Pfeiffer, W. Schwippert. 2001. Neural Modulation of Visuomotor Functions Underlying Prey-Catching Behaviour in Anurans: Perception, Attention, Motor Performance, Learning. Elsevier, 417: 61.

Hammerson, G., G. Santos-Barrera. 2004. "Pseudacris cadaverina" (On-line). The IUCN Red List of Threatened Species. Accessed February 18, 2020 at https://dx.doi.org/10.2305/IUCN.UK.2004.RLTS.T55890A11374045.en..

Stebbins, R., S. McGinnis. 2012. Field Guide to Amphibians and Reptiles of California. Berkeley and Los Angeles, California: California Natural History Guides.

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