Little is known about the lifespan of Pacific treefrogs, either in the wild or in captivity. There is record of a captive Pacific treefrog that lived for 9 years. Other chorus frogs in the genus Pseudacris have an average lifespan of approximately 5 years in the wild. Closely related mountain chorus frogs P. brachyphona live for approximately 7 years in the wild.
Range lifespan
Status: captivity: 9 (high) years.
Garter snakes are known predators of Pacific treefrogs. Other predators include other species of frogs, raccoons, Virginia opossums, fish, and birds. Their primary defense against predators is to remain motionless, though this technique is only effective if the frog matches its environment very well. They also tend to hide in areas of tall grass or jump into water when threatened. The primary predator of Pacific treefrog tadpoles is mosquitofish. Research has shown that even when presented with mosquito larva, mosquitofish often prefer treefrog tadpoles. Other predators on tadpoles include numerous species of fish and some aquatic invertebrates.
The best defense of Pacific treefrogs against predation is their camouflage. The coloration of their dorsal surface varies from shades of brown to shades of green. They tend to stay in habitats that have coloring similar to their bodies. Recent studies have shown that Pacific treefrogs can vary their coloring based on the presence or absence of green foliage. In addition, during spring and summer, when green foliage is abundant, these frogs tend to be greenish in color; in fall and winter, they tend to be shades of brown.
Known Predators:
Anti-predator Adaptations: cryptic
Pacific treefrogs are a small, slender frogs with large toe pads. They have smooth skin that varies in color from light-brown to bright-green. Pacific tree frogs with red or brown backs also have been reported, but are thought to be rare. This species typically has darker markings on its body, including stripes on its dorsal surface and sides of its heads, which vary in intensity and in some individuals may be nearly absent. A dark triangular marking between the eyes is also common. Generally, a line of broken spots extends down the ventral surface to the groin area. The legs, arms, and feet are generally darker than the rest of the body. Within their natural range, Pacific treefrogs are the only frogs with padded toes and dark markings. Pacific treefrogs can change their body color depending on environmental conditions and need for camouflage to avoid predation. Recent research suggests that P. regilla changes color seasonally to match the presence or lack of green foliage. Color variation has also been associated changes in mean temperature. At high temperatures, these frogs often turn a shade of yellow. Under cooler temperatures, they return to their more typical darker colors. Males often are slightly different in color than females. Their upper body can be a dark gray olive color and may have a brown band extending through the eye and a yellow stripe along the upper lip. Females may be similar to males in color, but with little to no yellow stripe on the groin. During breeding season, it is easier to distinguish males from females by their different colored throats. Females have a smooth white throat while males have a dark brown or yellow throat with wrinkled skin.
Adult body size in Pacific treefrogs ranges from 2.5 to 4.8 cm. Mature females tend to be larger than males, which is not uncommon for anurans. Body mass of newly hatched tadpoles is, on average, 0.24. After 30 days, weight increases to between 0.35 and 0.45 g, which is more typical of adult Pacific treefrogs.
Pacific treefrogs, Sierran treefrogs, and Californian treefrogs were once considered a single species and referred to as Baja treefrogs (Pseudacris hypochondriaca). These species were later reclassified primarily due to differences in geographic ranges. These three species look very similar, except for the bumpy skin of the Sierran and Californian treefrogs.
Average mass: 0.35 g.
Range length: 2.5 to 4.8 cm.
Other Physical Features: ectothermic ; heterothermic ; bilateral symmetry ; polymorphic
Sexual Dimorphism: female larger; sexes colored or patterned differently
Pacific treefrogs have a very rapid call that has been described as a “kreck-ek” noise. The rapid call is called the chorus note; this serves to bring individuals in the area together for breeding. Pacific treefrogs also have an encounter call that warns other males not to get too close during mating season. This differs from their normal call, which is lower pitched and longer. Research has shown that males avoid overlapping calls in order to increase each male’s chance to attract a mate. Typically, up to three males can call without overlapping, if timing is well synchronized. Pacific treefrogs have well developed senses of sight, smell, and hearing. Hearing is particularly well-developed, as these frogs must be able to call to each other during mating season.
Communication Channels: visual ; tactile ; acoustic
Other Communication Modes: choruses
Perception Channels: visual ; acoustic
Pacific treefrogs occur in a variety of habitats, including mesic and xeric forests, high altitude mountains, and desert steppe. Most commonly, they occur in moist environments, especially in low vegetation near water. Typically, they are found near lakes, ponds, rivers and streams. They can also be found in residential areas. Outside of breeding season, they often are seen near large, which is thought to provide shelter from predators. Pacific treefrogs are tolerant of rapid changes in weather and varying climatic conditions. Populations extend across a broad elevational range, from sea level to nearly 3500 m; however, most populations occur around 914 m above seal level.
Range elevation: 0 to 3500 m.
Average elevation: 914 m.
Habitat Regions: temperate ; terrestrial ; freshwater
Terrestrial Biomes: savanna or grassland ; chaparral ; forest
Aquatic Biomes: lakes and ponds; rivers and streams
Wetlands: marsh ; swamp ; bog
Other Habitat Features: suburban
Pacific treefrogs (Pseudacris regilla) are common throughout North America, west of the Rocky Mountains. Their geographic range extends from southern British Columbia, Canada, south through Washington, Oregon, and California, to Baja California, Mexico. Their eastern-most portion of their geographic range extends into Nevada, Idaho, and Montana. Pacific treefrogs also have been reported in deserts of southern California, where they are thought to have been introduced.
Biogeographic Regions: nearctic (Introduced , Native )
As tadpoles, Pacific treefrongs consume a variety of aquatic invertebrates and detritus. They mostly feed on algae, bacteria, and floating vegetative debris. Adults primarily consume terrestrial invertebrates, with only 4.8% of their diet coming from aquatic sources. Adults usually feed at night on invertebrate species, often consuming great quantities of flying insects. During breeding season, adults may feed during the day. Adults capture insects by extending their tongues. The tongue is coated by a sticky secretion that traps the insect, along with any debris or dirt near the insect. Food items are typically swallowed whole.
Animal Foods: insects; terrestrial non-insect arthropods
Plant Foods: algae
Other Foods: detritus ; microbes
Primary Diet: carnivore (Insectivore ); herbivore (Algivore)
Pacific treefrogs are insectivorous and may help control a number of insect pest species throught their geographic range. In addition, a number of different species depend on Pacific treefrogs as their primary prey. There is no information on the potential parasites of this species.
As an insectivore, Pseudacris regilla likely helps control insect pest species throughout their geographic range.
Positive Impacts: controls pest population
There are no known adverse effects of Pseudacris regilla on humans.
Breeding season for P. regilla extends from January to mid-May. During this time, females lay eggs which are brown and yellow. Males externally fertilize the eggs, which are usually laid in gently moving water, in clutches of 5 to 70 eggs, and must be kept moist.
Pacific treefrog tadpoles are of medium size, typically about 46.6 mm long, and brown in color. Tadpole tails are not flagellated. Pacific tree frogs show rapid growth during the first summer after hatching. Tadpoles undergo metamorphosis between 50 and 80 days of age. During the metamorphosis, individuals typically measure between 12 and 15 mm long. Within two months of metamorphosis, individuals approximately double in length. Newly metamorphosed frogs leave the breeding area and seek habitats similar to that of an adult frog. Pacific treefrogs reach sexual maturity quickly and participate in the first mating chorus following their hatching.
Development - Life Cycle: metamorphosis
Pacific treefrogs are classified as a species of least concern on the IUCN's Red List of Threatened Species. They have a broad geographic range and are the most common frog in the United States, west of the Rocky Mountains. The greatest current threat to Pacific treefrogs appears to be increased predation from non-native mosquitofish; however, this threat does not occur throughout the entirety of the Pacific treefrogs geographic range.
US Federal List: no special status
CITES: no special status
State of Michigan List: no special status
IUCN Red List of Threatened Species: least concern
Breeding occurs seasonally for Pacific tree frogs and typically occurs from winter to spring. This species is polygynous. During the breeding season, males often are found near small bodies of waters, particularly ponds, where they begin to sing. Females are attracted to males based on their calls and their different colored throats. Females prefer males that initiate calling. Once attracted, females move towards males. Males continue calling for several minutes, followed by several minutes of silence. Males continues this pattern until females are in their immediate vicinity.
Mating System: polygynous
Pseudacris regilla attracts mates using a choral song. Males call to females as loudly as possible and produce a croak so loud that they sound as though they are produced by multiple males. These sounds can be heard by numerous females. Once a female approaches, the male stops singing and attempts amplexus, a pseudocopulation act during which the male grasps the female with hist forelegs. Breeding takes place at night, near shallow water, typically after rainfall. Mating season usually extends from December to May, although some variation occurs. Altitude often affects the length of the breeding season.
Male Pacific tree frogs are occasionally aggressive during breeding season. They produce a warning call if another male approaches too closely. If the intruding male does not leave the area, the two frogs may fight until one departs. In addition, while attracting females, males can extend vocal pouches on their lower jaw, which helps in calling females. The act of copulation takes place in water. They are oviparous, and once the female enters the water, the male grasps her and helps to thrust out the eggs as he fertilizes them. Eggs are laid in small ponds or puddles. Typical broods range from 5 to 70 eggs. A jelly-like substance is left with the eggs to maintain moisture. Eggs remain in shallow water, often near twigs or leaves. Once reproduction is complete, both the male and female leave the water. Eggs hatch in three to four weeks, and within three to seven days, offspring develop into tadpoles. Development time varies with the temperature of the environment. Once they emerge from the egg, offspring use the jelly-like substance carried with the egg to sustain them for the first two to three days. Tadpoles then swim to shallow waters and ingest nearly any edible food item. When tadpoles reach three months of age, they metamorphose into froglets. This typically occurs between July and September.Research shows that as water temperature increases, development time decreases. In general, Pacific treefrogs reach sexual maturity in 1 to 2 years.
Breeding interval: Pseudacris regilla breeds once per year.
Breeding season: Pseudacris regilla breeds from January to May.
Range number of offspring: 5 to 70.
Average time to hatching: 3.5 weeks.
Average age at sexual or reproductive maturity (female): 1 to 2 years.
Average age at sexual or reproductive maturity (male): 1 to 2 years.
Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; fertilization (External ); oviparous
Once females lay eggs in the water, both males and females abandon the eggs. There is no parental investment.
Parental Investment: no parental involvement
The Pacific tree frog (Pseudacris regilla), also known as the Pacific chorus frog, has a range spanning the Pacific Northwest, from Northern California, Oregon, and Washington to British Columbia in Canada and extreme southern Alaska.[2] They live from sea level to more than 10,000 feet in many types of habitats, reproducing in aquatic settings. They occur in shades of greens or browns and can change colors over periods of hours and weeks.
The taxonomy of this frog has a very confusing history. First, the frog was moved from the genus Hyla to the genus Pseudacris in 1986, and Hyliola in 2016 (an elevation of the subgenus which has not been widely accepted).[2] In 2006, Recuero et al. split the frog into three species based on DNA evidence.[3] Recuero et al. used incorrect names for two of the three populations, but subsequent authors established that the correct name (i.e., the oldest available name) for the northern component is Pseudacris regilla, for the central one Pseudacris sierra, and for the southern one Pseudacris hypochondriaca.[2] This revision has been controversial[4] but the evidence is supported by other research (e.g., [5][6]), and is followed in this article.
The Pacific tree frog grows up to 2 inches from snout to urostyle. The males are usually smaller than the females and have a dark patch on their throats. The dark patch is the vocal sac, which stretches out when the male is calling. Pacific tree frogs can be a number of different colors, including green, tan, reddish, gray, brown, cream, and black, but most are a shade of green or brown, with pale or white bellies. They have a variety of dark and spotty markings on their backs and sides and can be identified by a black or dark brown eye stripe that stretches from the nose, across the eye, and back to the shoulder. They can change color seasonally to better match their environments. Their skin is covered in small bumps. They have long legs compared to their bodies and they tend to be slender. Their toes are long and only very slightly webbed. On the end of each toe is a round, sticky toe pad or disk used for climbing and sticking to surfaces. Males also have an extra, and far less noticeable toe on their outer thumbs used exclusively in amplexus. Fertilization is external.
Pacific tree frogs are common on the Pacific coast of Oregon and Washington, but they are found from extreme northern California to British Columbia. They can also be found in Idaho. A small population also exists in a pond on Revillagigedo Island near Ketchikan, Alaska, having been intentionally introduced there in the 1960s.[7] They are found upland in ponds, streams, lakes and sometimes even further away from water; their habitat includes a wide variety of climate and vegetation from sea level to high altitudes. The Pacific tree frog makes its home in riparian habitat, as well as woodlands, grassland, chaparral, pasture land, and even urban areas including back yard ponds. Eggs of the Pacific tree frog may be consumed by the rough-skinned newt[8] and other amphibians.
The Pacific tree frog begins mating in early winter to early spring. Since these frogs are so widespread geographically, their breeding season is thought to be determined by local conditions. When it is time, the males migrate to the water. They then make a call at the same time. This lures the females to the water and they mate. The females lay their eggs in clumps of 10–90, and usually put them on and under vegetation and leaf litter in the pond. Females usually lay their eggs in shallow, calm water that has little action around it. If they survive, embryos will hatch into tadpoles within one to three weeks. The tadpoles feed on periphyton, filamentous algae, diatoms, and pollen in or on the surface of the water. They feed using suction, and a beak-like structure that helps scrape vegetation off surfaces.
The species attracts mates using a choral song. Males call to females as loudly as possible and produce a croak so loud that they sound as though they are produced by multiple males. These sounds can be heard by numerous females. Once a female approaches, the male stops singing and attempts amplexus. Breeding takes place at night, near shallow water, typically after rainfall. Mating season usually extends from December to May, although some variation occurs. Altitude often affects the length of the breeding season. (Dickerson, 1906; Grinnell and Storer, 1924; Schaub and Larsen Jr, 1978)
Metamorphosis usually follows about two to two and a half months later, but experience raising these tadpoles shows that some may delay metamorphosis, changing up to five months after hatching. The survival rate of these delayed metamorphs is lower, and the evolutionary utility of this delayed metamorphosis is uncertain. It may be related to the prevalence of fire in their natural ecosystem.
During the final stages of transformation when the tadpoles have four limbs and a tail, they stop feeding for a short time while their mouths widen and their digestive systems adjust from herbivorous to carnivorous.
For the most part, Pacific tree frogs are nocturnal, but they have been spotted during the day. These frogs spend a lot of time hiding under rotten logs, rocks, long grasses, and leaf litter, where they are very difficult to see unless they move. When they hunt, their toe pads allow them to climb on vegetation and other surfaces where they are to ambush their prey. Much of their diets consists of spiders, beetles, flies, ants, and other insects and arthropods; they can and do eat insects that are almost as large as they are, and will expand their bodies slightly to accommodate these meals.
Pacific tree frogs mature quickly, and usually mate the season after metamorphosis. Predators include snakes, raccoons, herons, egrets, and other small mammals and reptiles.
When they sense potential food nearby, they commonly twitch a toe to attract it within easy reach of their tongues. They can live up to 8 years in captivity.
They produce several call types.[9] These include the males' advertisement call, commonly described as "ribbit" or "crek-ek", as well as an encounter trill call. The cre-ek call can be quite loud and can thus be heard from very far away. Males also produce a "dry land call", a long cre-ee-ee-eeek, that can be heard anytime in the year except during the coldest and driest periods. Pacific tree frogs are the most commonly heard frogs along much of the West Coast of the United States.
Previously, adults were thought to occur in two different fixed colors: green and brown. Now, some of them have been found to be able to change between the two. They can also change from lighter to darker, shift from patterned markings to pure colors and vice versa, and even display combinations of colors, brown/green being the most frequent.
These color-changing morphs are triggered not by color change in their environments, but a change in background brightness. This type of environmental change would be caused by seasonal fluctuation. A full change in the dorsal coloration of a color morph can take from weeks to months, but initial changes can occur in just a few hours.[10] This has been shown to be a very useful cryptic survival feature for these frogs.
Skin color is produced via pigment cells called chromatophores. Three types of chromatophores are commonly found in amphibians: Xanthophores, which contain yellow, orange, or red pigments and are found uppermost on the dermis; iridophores, which lie below the xanthophores and function by reflecting and scattering white light up through them (in the case of Pseudacris regilla and many other North American frogs, iridophores reflect blue light through the yellow pigment cells above to create a green frog) and melanophores, which are the deepest pigment cells and are responsible for the presence of black and brown pigments.
A rare, recessive "blue morph" is known. One is housed at the Humboldt State University Natural History Museum in Arcata, California.[1] This mutation might inhibit the xanthophores' ability to produce yellow pigments, thus the normally green frog (possibly of the color-unchanging type) appears blue.
Green color morph
Blended color morph green with brown stripes
Brown color morph held in hand.
Side view showing a color variant.
Research was done on Pacific tree frogs to discover if they have homing instincts and what was their main source for knowing where their home was. To find the answer, these frogs were marked and moved 300 yards away from their pond. Several days later, the researchers did a recapture on the original pond in which 66.3% of the frogs were recaptured, indicating there was some source of homing instinct. This was made apparent again when 24 frogs were placed into a larger pond, and 20 of those frogs returned to their original pond. The frogs' movement patterns and olfactory, auditory, and kinesthetic senses could be explanations for the homing, but not a single factor was able to explain the results, indicating that these frogs might be using all or a combination of these factors for homing.[11]
These frogs (if one includes the two very closely related species, as discussed above) are the most common frogs on the West Coast of North America. Although Pacific tree frogs remain abundant, some other species found in the same areas, such as California red-legged frogs, are declining. Most populations of tree frogs appear healthy, and they have no concern or conservation status.
In 2007, the Pacific tree frog was named the state amphibian of the State of Washington.[12] It is also a very important species in all of the regions where it is found because it is a keystone species. Many other species, such as garter snakes, depend upon its abundance as a prey item for their survival.
The Pacific tree frog (Pseudacris regilla), also known as the Pacific chorus frog, has a range spanning the Pacific Northwest, from Northern California, Oregon, and Washington to British Columbia in Canada and extreme southern Alaska. They live from sea level to more than 10,000 feet in many types of habitats, reproducing in aquatic settings. They occur in shades of greens or browns and can change colors over periods of hours and weeks.
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