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).
- Biogeographic Regions
- neotropical
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).
- Habitat Regions
- temperate
- terrestrial
- Aquatic Biomes
- lakes and ponds
- rivers and streams
- temporary pools
- Other Habitat Features
- suburban
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).
- Other Physical Features
- ectothermic
- bilateral symmetry
- Sexual Dimorphism
- sexes colored or patterned differently
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).
- Development - Life Cycle
- metamorphosis
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)
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).
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).
- Key Behaviors
- nocturnal
- motile
- hibernation
- aestivation
- territorial
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).
- Communication Channels
- acoustic
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.
- Primary Diet
- carnivore
- planktivore
- Animal Foods
- insects
- Plant Foods
- phytoplankton
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).
- 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).
- 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).
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).
Additional Links
Contributors
Selina Martinez (author), California State University, San Marcos, Tracey Brown (editor), California State University, San Marcos, Galen Burrell (editor), Special Projects.
- Neotropical
-
living in the southern part of the New World. In other words, Central and South America.
- native range
-
the area in which the animal is naturally found, the region in which it is endemic.
- 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.
- 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.
- forest
-
forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.
- mountains
-
This terrestrial biome includes summits of high mountains, either without vegetation or covered by low, tundra-like vegetation.
- suburban
-
living in residential areas on the outskirts of large cities or towns.
- nocturnal
-
active during the night
- motile
-
having the capacity to move from one place to another.
- 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.
- 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
- acoustic
-
uses sound to communicate
- visual
-
uses sight to communicate
- acoustic
-
uses sound to communicate
- phytoplankton
-
photosynthetic or plant constituent of plankton; mainly unicellular algae. (Compare to zooplankton.)
- 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.
- carnivore
-
an animal that mainly eats meat
- insectivore
-
An animal that eats mainly insects or spiders.
- planktivore
-
an animal that mainly eats plankton
- ectothermic
-
animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature
- 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.
- 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.
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., 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 .
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 .
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.