Animal Diversity Web

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)

• Biogeographic Regions
• neotropical
  • native

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)

• Habitat Regions
• temperate
• terrestrial

• Terrestrial Biomes
• chaparral
• forest
• mountains

• Aquatic Biomes
• lakes and ponds
• rivers and streams
• temporary pools

• Other Habitat Features
• suburban

• 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)

• Other Physical Features
• ectothermic
• bilateral symmetry

• 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)

• 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)

• 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)

• 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). (Cocroft and Ryan, 1995; Ervin, 2020; Ewert, et al., 2001)

• Communication Channels
• acoustic

• Perception Channels
• visual
• 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. (Cun­ning­ham, 1964; Ervin, 2020)

• Primary Diet
• carnivore
  • insectivore
• 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). (Cun­ning­ham, 1964; Ervin, 2020; Steb­bins and McGin­nis, 2012)

• Anti-predator Adaptations
• cryptic

• Known Predators

  • Rainbow trout (Oncorhynchus mykiss), two-striped garter snakes (Thamnophis hammondii), green sunfish (Lepomis cyanellus).

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)

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)

• IUCN Red List

  Least Concern

• US Federal List

  No special status

• CITES

  No special status

• State of Michigan List

  No special status

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.

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.