• If you are citizen of an European Union member nation, you may not use this service unless you are at least 16 years old.

  • Stop wasting time looking for files and revisions. Connect your Gmail, DriveDropbox, and Slack accounts and in less than 2 minutes, Dokkio will automatically organize all your file attachments. Learn more and claim your free account.


Pseudacris regilla, Pacific chorus frog

Page history last edited by PBworks 13 years, 1 month ago

Pseudacris regilla

        Pacific Chorus Frog



Kingdom: Animalia

    Phylum: Chordata

        Subphylum: Vertebrata

            Class: Amphibia

                Order: Anura

                    Family: Hylidae (New World tree frogs)

                        Genus: Pseudacris (chorus frogs)


Image: californiaherps.com  


Other names:

    *Pacific Hyla

    *Oregon Wood Frog

    *Pacific Tree Frog

    *Pacific Tree-Toad

    *Pacific Treefrog

    *Northern Pacific Treefrog

    *Cascade Mountain Treefrog

    *Western Oregon Treefrog

    * Hyla regilla (former classification)


Distribution/ Range:

   Pseudacric regilla, the Pacific chorus frog, ranges from Baja California and Mexico, north to British Columbia, Canada.  They also stretch as far inward as Arizona, Utah, Montana, and as far north to a few regions of southern Alaska.  The species occurs from sea level to approximately 3000 meters above sea level.


Distribution Map: http://www.natureserve.org/explorer



Distribution within Idaho:

Image: Stephen Burton 1999, Idaho Digital Atlas



Pseudacris regilla are very diverse in the habitat types they are able to occupy, as long as there is a source of water.  These frogs have been found in agricultural areas, deserts, grasslands, forests, rocky areas, and especially riparian areas such as springs, ponds, streams, and swamps.  Their adaptable character enables them to live among rocks, timber, vegetation, undergrowth, and debris.



http://zoology.okstate.edu/zoo_fclt/bidwell/     www.ecomagic.org


Bidwell Lab- Oklahoma State University

Boreal Chorus Frog (Pseudacris triseriata)                                                         Pacific Chorus Frog (Pseudacris regilla)


Adult Identification:

The Pacific Chorus frog is most typically confused with the Boreal Chorus frog; both have many similar features and variable pigmentation.  Distinguishing features of Pacific Chorus Frogs are that they have a dark stripe through their eye (the stripe typically does not progress down the rest of the body as in Boreal Chorus frogs, but extends only to the shoulder), and tend to have a "Y" shaped mark on their heads.  Their fore- and hindlimbs have toe pads used for climbing and have only slight webbing between the toes.  The nose of Pacific chorus frogs tend to be more rounded than that of the Boreal.  Pacific Chorus frogs reach about 2 inches in length, and the females are typically larger than males.  Their color is variable throughout the species as well as individuals (ranging from dark brown to bright green- with stripes and spots variable) with their ventral side being lighter.



Tadpole distinction:

The tadpoles are distinguishable by:

    - being darker brown on the dorsal side and lighter on their ventral side

    - their eyes are further back on the head

    - their dorsal fin arches less than that of the Boreal Chorus Frog

    - intestines are not visible



    Pacific Chorus frogs are typically solitary except during the breeding season when they may form large groups and breeding pairs.  Males are very loud and territorial, calling at night to ward off other males from their territory.  The species are largely nocturnal, especially during dry periods; this is a behavioral characteristic to help them regulate their water composition.  The exception to this is during the breeding season when they may be active during the day.  Food capture of insects is made easier by their tongue which is long, quick and sticky.  This form of feeding is a response to motion, but can, at times, being a disadvandage due to the excess of debris that can be picked up by the sticky tongue. 



        - Adult P. regilla feed soley on insects which they capture with their specialized tongue.  Some of this prey includes beetles, flies, spiders, ants, isopods such as woodlice, gnats, and mosquitoes.

       - P. regilla as tadpoles are herbivorous; feeding on plants, algae, and other organic matter.







       - snakes

       - carnivorous aquatic insects

       - various other mammals and birds



    The breeding season is the only time that individuals come together in ponds to form groups and to breed.  Individuals are sexually mature at one year of age.  Males call to establish territory and attract females, this call can sometimes be heard from more than a mile away.  Females will lay small clusters of eggs (between 9-70) that the male fertilizes as the female ejects them from her body.  Some females have been documented laying eggs in temporary waters that do not last long enough for the tadpoles to hatch or to sustain them while the mature, this in turn leads to lower reproduction numbers.  The fertilized egg cluster will float on the water until tadpoles hatch in about 3-5 weeks depending on the water temperature.  These temporary ponds tend to have few predators, ensuring better odds of survival for tadpoles.  There is no parental interaction after the eggs have been laid.  After hatching, tadpoles are approximately 1 cm in length and are gray-ish green.  They follow the growth process of other frogs by gradually growing legs and their tail reduces in length as they reach maturity.  When full grown they will vary from 1-2 inches in length and will vary greatly in color.


Environmental Significance:

    Pacific chorus frogs like many other amphibians, are an indicator species.  An indicator species is defined by the United State Geological Survey (USGS) as "an organism whose presence or state of health is used to identify a specific type of biotic community or as a measure of ecological conditions or changes occuring in the environment."  This means that amphibians, such as P. regilla (which are the most abundant amphibian in the Pacific Northwest), are an excellent indicator of polluntants in the air and water due to the nature of their permeable skin.  Effects of pollutants can be additional or missing limbs, deformed or translocated eyes, changes in webbing, or any other number of problems. 


Scientific Study:


Stegen, James C, CM Gienger, Lixing Sun.  2004.  The control of color change in the Pacific tree frog, Hyla regilla.  Canadian Journal of Zoology.  82: 889-896.


    This study investigates the ability of anurans to change color and what factors trigger or have an effect on the ability to change their color.  Many instances of color change in anurans as well as other reptiles and amphibians has been linked to the purpose of blending into the individuals surruondings. However, there are some hypotheses that suggest there may be other reasons for color change.  This article suggest that anurans may change color to blend in with their surroundings as well as for water and temperature regulation.  Stegen, Gienger, and Sun analyze these possibilities by directly looking at the rate of color change, and looked at the "individual and interactive effects of temperature, light intensity, and background on the rate of hue, lightnesss, chroma, and whole color change in H. regilla."

    This study was conducted using 20 adult Pacific Chorus frogs that were selected to "maximize the range of color morphologies."  Measurements were taken of all 20 of these frogs before any maniupulations took place to determine their natural individual lightness, hue, and chroma.  Then, measurements of the test backgrounds and habitat were also taken to determine the values of the same variables. 

    Before a test, the frogs were placed on a petri dish (to minimize handling) and placed in a completely darkened environment on a black surface for two hours.  This time allows the individual to completely darken an relax.  When this time is complete, the frog is moved onto the selected background (either brown or green, mimicking natural cat-tail environments) and images are taken every minute for the next two hours to record color change.

    Basic conclusions are that the frogs as a whole were able to change color slower on the brown surface but matched the brown background better than the green background.  Also, the frogs were not able to change color as rapidly if the intensity of the light was higher, but they were able to better match the background at a higher intensity.  Similarly, the frogs changed color slower at a higher temperature but at this higher temperature were able to match their background better.  In regards to temperature, there was also a variation in background, the rate of change was faster on the brown background than on the green background.

    Overall, this study concluded that there are definitely other factors that can play a role in color chage besides the simple reason of blending in with the individuals surroundings.  The researches state that they "support the idea that physiological color change has evolved as a mechanism to allow rapid background matching as a tree frog moves from one location to another."  Earlier in the article the scientists state that frogs are more vulnerable to a predator when moving around than they are when they are still.  This is due not only to movement, but also the variation in color that will inevitably occur as an individual moves from one area to another (the color change of frog to background).  The ability of an individual to change more rapidly is a definite survival instinct and those individuals that are healthier or more fit to change color more rapidly, completely, and effiiently will be more likely to thrive and contribute to the gene pool.


 Interesting Facts:

    - P. regilla can change their body color depending on temperature or moisture

    - They do not chew or break down thier food

    - Native Americans believe that there is a tree frog to counter every individual on the earth, this led to a great respect of this species of frog.

    - Ambient frog noises or background "ribbits"used in most Hollywood movies is actually the call of the Pacific Chorus frog.




YouTube plugin error






AmphibiaWeb: Information on amphibian biology and conservation.  2007.  20 Sept 2007.  <http://amphibiaweb.org/cgi-bin/amphib_query?query_src=&special=maps&genus=Pseudacris&species=regilla&photos=yes>


Animal Diversity Web: University of Michigan Museum of Zoology.  2006.  22 Sept. 2007.  <http://animaldiversity.ummz.umich.edu/site/accounts/information/Hyla_regilla.html>


Center for Limnology: University of Wisconsin.  25 Sept. 2007.  <http://limnology.wisc.edu/personnel/pieter/Hidden%20Stuff/amphibpictures.htm>


Digitial Atlas of Idaho: Pseudacris regilla.  Idaho State University. 2000.  10 Sept. 2007.  <http://imnh.isu.edu/digitalatlas/bio/amph/main/amphmnfr.htm>


Frost, Darrel R.  Amphibian Species of the World: an Online Reference.  American Museum of Natural History.  2007.  17 Sept. 2007.  <http://research.amnh.org/herpetology/amphibia/references.php?id=12418>


Global Amphibian Assessment.  IUCN, Conservation International, and NatureServe.  2006.  12 Sept 2007.  <http://www.globalamphibians.org/servlet/GAA?searchName=Pseudacris+regilla>


Magic Inc.  2007.  20 Sept 2007.  <http://www.ecomagic.org/salamander/frog-1.jpg>


NatureServe Explorer: Pseudacris regilla.  2007.  15 Sept. 2007 <http://www.natureserve.org/explorer/servlet/NatureServe?searchName=Pseudacris+regilla>


Oklahoma State University, Department of Zoology: Bidwell Lab.  2007.  17 Sept. 2007.  <http://zoology.okstate.edu/zoo_fclt/bidwell/images/pseudacris_triseriata_slc.jpg>


Photo Index of California Frogs and Toads.  2007.  4 Sept. 2007 <http://www.californiaherps.com/frogs/frogspics.html>


Stegen, James C, CM Gienger, Lixing Sun.  2004.  The control of color change in the Pacific tree frog, Hyla regilla.  Canadian Journal of Zoology.  82: 889-896.


Created by: Vicki Taylor

Comments (0)

You don't have permission to comment on this page.