Hyla regilla is a small frog, about 3/4 to 2 inches, that has expanded toe disks and a black eye-stripe (Stebbins 1985). The stripe runs from the tip of the snout posteriorly through the eye to the forelimb insertion (Grismer 2002). The stripe is hard to see in dark frogs, but it is always present. The dorsal coloration is highly variable, and could be gray, tan, green, brown, or black, and it may change color from dark to light within a few minutes. It often has a triangular dark spot on the head and dark spots on the back and legs, and the clarity of these spots changes as the frog changes its color phase. Its limbs are crossbanded or blotched with dark color, and the posterior has a yellow or orange color, especially on the under surfaces of the limbs, the rear of the femur, and in the groin. Males have a wrinkled and dusky throat. When the males vocal sac is deflated, often 8 to 12 longitudinal folds are present (Stebbins 1985). It has webbed hind toes with a margin of the web between successive toes. Skin is usually smooth with a few tubercles but occasionally quite rough. It has a round tympanum, that is anywhere from 1/4 to slightly over 1/2 the size of the eye opening, located in the eye stripe. The thenar tubercle is elongated and ovoid, while the palmar tubercle is made of 3 small, closely associated tubercles totaling the size of the thenar tubercle (Stebbins 1951).
A similar species, Hyla cadaverina, the California Treefrog, usually does not have an eye-stripe, has larger toe pads, and more fully webbed hind toes. H. cadaverina is also rarely green. Another similar species, Hyla eximia, the Mountain Treefrog, the eye-stripe extends beyond the shoulder and webbing is reduced (Stebbins 1985).
It is certain that there are isolated populations of H. regilla in many unexplored canyons of the Sierra la Giganta that harbor hidden permanent springs. In some water systems west of San Ignacio, there is evidence that H. regilla is being displaced by the bullfrog, Rana catesbeiana (Grismer 2002).
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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 )
Regularity: Regularly occurring
Type of Residency: Year-round
Regularity: Regularly occurring
Type of Residency: Year-round
Global Range: (200,000-2,500,000 square km (about 80,000-1,000,000 square miles)) The range of P. regilla (sensu lato) extends from southern British Columbia in Canada southward through the United States to southern Baja California, Mexico, and east to Montana, Idaho, and Nevada. The species also occurs on the Channel Islands off southern California (Stebbins 2003). Desert populations in southern California probably were introduced, as were some populations in Arizona. An introduced population occurs in the Queen Charlotte Islands, British Columbia (Reimchen 1990), Canada, and on Revillagigedo Island in Alexander Archipelago, Alaska, where it was introduced in 1960 and is breeding (Waters 1992, Hodge 2004). Overall elevational range extends from sea level to around 3,540 meters (Stebbins 2003).
Under the taxonomic arrangement proposed by Recuero et al. (2006), the distributions of the species in the P. regilla complex presumably would be approximately as follows (Recuero et al. did not provide distributional details):
P. regilla: extreme southern Alaska (introduced), British Coumbia, Washington, western Oregon, and northern California.
P. sierra: central California, Nevada, eastern Oregon, Idaho, western Montana, and presumably extreme northwestern Utah (extirpated?).
P. hypochondriaca: southern California, southern Nevada, southwestern Utah (extirpated?), and western Arizona south to southern Baja California.
This frog is well distributed along 90 km of the lower Colorado River and its backwaters from Davis Camp, just below Davis Dam, to Castle Rock in upper Lake Havasu, but the native versus exotic status of these populations is unclear (Rorabaugh et al. 2004). In Arizona, this species has been recorded as an apparent introduction at Middle Spring and a nearby stock tank in the Virgin Mountains, Mohave County, and at two central Arizona plant nurseries (Rorabaugh et al. 2004). It persisted for at least 19 years and successfully bred at one nursery, where it was reportedly introduced on ornamental plants imported from San Diego (Rorabaugh et al. 2004).
Distribution and Habitat
Distributed from mainland British Columbia and Vancouver Island through Washington, Oregon, California, and the tip of Baja California. H. regilla can be found on Catalina, Santa Rosa, and Santa Cruz, islands off the coast of southern California, and on Isla Cedros, an island off the west coast of central Baja California. Distribution also goes east to eastern Nevada and western Montana. It lives in habitats from sea level to 11,000 feet in the Sierra Nevada (Grisner 2002). It seeks cover in many places, including rock fissures, under bark, in vegetation along streams, in rodent and other burrows, in nooks and crannies in buildings, and in culverts. It can be found in springs, ponds, irrigation canals, streams, and other bodies of water, but it has also been found as far as ½ mile from water (Stebbins 1951). Out of the water, it frequents habitats like grassland, chaparral, woodland, desert oases, forest, and farmland (Stebbins 1985).
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
Length: 5 cm
Catalog Number: USNM 9182
Collection: Smithsonian Institution, National Museum of Natural History, Department of Vertebrate Zoology, Division of Amphibians & Reptiles
Locality: Puget Sound, Locality In Multiple Counties, Washington, United States, North America
Catalog Number: USNM 15409
Collection: Smithsonian Institution, National Museum of Natural History, Department of Vertebrate Zoology, Division of Amphibians & Reptiles
Locality: Sacramento River, Locality In Multiple Counties, California, United States, North America
Central and Southern Cascades Forests Habitat
The Oregon slender salamander is endemic to the Central and Southern Cascades forests ecoregion. The Central and Southern Cascades forests span several physiographic provinces in Washington and Oregon, including the southern Cascades, the Western Cascades, and the High Cascades, all within the USA. This ecoregion extends from Snoqualmie Pass in Washington to slightly north of the California border. The region is characterized by accordant ridge crests separated by steep, deeply dissected valleys, strongly influenced by historic and recent volcanic events (e.g. Mount Saint Helens).
This ecoregion contains one of the highest levels of endemic amphibians (five of eleven ecoregion endemics are amphibians) of any ecoregion within its major habitat type. The threatened Northern spotted owl has been used as an indicator species in environmental impact assessments, since its range overlaps with 39 listed or proposed species (ten of which are late-seral associates) and 1116 total species associated with late-seral forests. Late-seral forests in general are of national and global importance because they provide some of the last refugia for dependent species, and perform vital ecological services, including sequestration of carbon, cleansing of atmospheric pollutants, and maintenance of hydrological regimes.
There are a number ofl amphibian taxa present in the Central and Southern Cascades ecoregion; the totality of these amphibian taxa are: the Rough-skinned newt (Taricha granulosa); the endemic and Vulnerable Shasta salamander (Hydromantes shastae); the endemic and Vulnerable Oregon slender salamander (Batrachoseps wrighti); the Endangered Dunn's salamander (Bolitoglossa dunni); the Northwestern salamander (Ambystoma gracile); the Near Threatened western toad (Anaxyrus boreas); the Vulnerable Oregon spotted frog (Rana pretiosa); the Near Threatened Cascades frog (Rana cascadae); Coastal tailed frog (Ascaphus truei); Near Threatened Larch Mountain salamander (Plethodon larselli); California newt (Taricha torosa); Pacific giant salamander (Dicamptodon ensatus); Cope's giant salamander (Dicamptodon copei); Monterey ensatina (Ensatina eschscholtzii); the Near Threatened Foothill yellow-legged frog (Rana boylii); Northern Red-legged frog (Rana aurora); Pacific chorus frog (Pseudacris regilla); Van Dyke's salamander (Plethodon vandykei), an endemic of the State of Washington, USA; Long-toed salamander (Ambystoma macrodactylum); and the Olympic torrent salamander (Rhyacotriton olympicus).
There are a moderate number of reptilian species present in the ecoregion, namely in total they are: Western pond turtle (Emys marmorata); Western fence lizard (Sceloporus occidentalis); Sharp-tailed snake (Contia tenuis); Ringed-neck snake (Diadophis punctatus); Rubber boa (Charina bottae); California mountain kingsnake (Lampropeltis zonata); Yellow-bellied racer (Coluber constrictor); Western rattlesnake (Crotalus viridis); Western gopher snake (Pituophis catenifer); Common garter snake (Thanophis sirtalis); Northwestern garter snake (Thamnophis ordinoides); Western skink (Megascops kennicottii); Southern alligator lizard (Elgaria multicarinata); and the Northern alligator lizard (Elgaria coerulea).
There is a considerable number of avifauna within the Central and Southern Cascades ecoregion; representative species being: Flammulated owl (Otus flammeolus); Western screech owl (Megascops kennicottii); White-tailed ptarmigan (Picoides albolarvatus); and White-headed woodpecker (Picoides albolarvatus).
There are a large number of mammalian taxa in the ecoregion, including: Bobcat (Lynx rufus); Wolverine (Gulo gulo); California ground squirrel (Spermophilus beecheyi); Yellow-bellied marmot (Marmota flaviventris); Ermine (Mustela erminea); Fog shrew (Sorex sonomae), an endemic mammal to the far western USA; Hoary marmot (Marmota caligata); Mountain beaver (Aplodontia rufa); and the Near Threatened red tree vole (Arborimus longicaudus); Yellow pine chipmunk (Tamias amoenus); and the American water shrew (Sorex palustris).
Puget Lowland Forests Habitat
Cope's giant salamander is found in the Puget lowland forests along with several other western North America ecoregions. The Puget lowland forests occupy a north-south topographic depression between the Olympic Peninsula and western slopes of the Cascade Mountains, extending from north of the Canadian border to the lower Columbia River along the Oregon border. The portion of this forest ecoregion within British Columbia includes the Fraser Valley lowlands, the coastal lowlands locally known as the Sunshine Coast and several of the Gulf Islands. This ecoregion is within the Nearctic Realm and classified as part of the Temperate Coniferous Forests biome.
The Puget lowland forests have a Mediterranean-like climate, with warm, dry summers, and mild wet winters. The mean annual temperature is 9°C, the mean summer temperature is 15°C, and the mean winter temperature is 3.5°C. Annual precipitation averages 800 to 900 millimeters (mm) but may be as great as 1530 mm. Only a small percentage of this precipitation falls as snow. However, annual rainfall on the San Juan Islands can be as low as 460 mm, due to rain-shadow effects caused by the Olympic Mountains. This local rain shadow effect results in some of the driest sites encountered in the region. Varied topography on these hilly islands results in a diverse assemblage of plant communities arranged along orographically defiined moisture gradients. Open grasslands with widely scattered trees dominate the exposed southern aspects of the islands, while moister dense forests occur on northern sheltered slopes characterized by Western red cedar (Thuja plicata), Grand fir (Abies grandis), and Sword fern (Polystichum munitum) communities.
There are only a small number of amphibian taxa in the Puget lowland forests, namely: Cope's giant salamander (Dicamptodon copei); Monterey ensatina (Ensatina eschscholtzii); Long-toed salamander (Ambystoma macrodactylum); Western redback salamander (Plethodon vehiculum); Northwestern salamander (Ambystoma gracile); Pacific chorus frog (Pseudacris regilla); Coastal giant salamander (Dicamptodon tenebrosus); Rough-skin newt (Taricha granulosa); the Vulnerable Spotted frog (Rana pretiosa); Tailed frog (Ascopus truei); and Northern red-legged frog (Rana aurora).
Likewise there are a small number of reptilian taxa within the ecoregion: Common garter snake (Thamnophis sirtalis); Western terrestrial garter snake (Thamnophis sirtalis); Northern alligator lizard (Elgaria coerulea); Western fence lizard (Sceloporus occidentalis); Northwestern garter snake (Thamnophis ordinoides); Sharp-tailed snake (Contia tenuis); Yellow-bellied racer (Coluber constrictor); and Western pond turtle (Clemmys marmorata).
There are numberous mammalian taxa present in the Puget lowland forests. A small sample of these are:Creeping vole (Microtus oregoni), Raccoon (Procyon lotor), Southern sea otter (Enhydra lutris), Mink (Mustela vison), Coyote (Canis latrans), Black-tailed deer (Odocoileus hemionus), Pallid bat (Antrozous pallidus), and Harbour seal (Phoca vitulina).
A rich assortment of bird species present in this ecoregion, including the Near Threatened Spotted owl (Strix occidentalis), Turkey vulture (Cathartes aura), Bald eagle (Haliaeetus leucocephalus), Blue grouse (Dendragapus obscurus), as well as a gamut of seabirds, numerous shorebirds and waterfowl.
Great Basin Shrub Steppe Habitat
The Great Basin shrub steppe is one of the ecoregions inhabited by the Utah prairie dog. The Great Basin shrub steppe ecoregion is situated in the most northerly of the four American deserts. Unlike the other three, which have almost exclusive ties to warm-temperate and tropical/subtropical vegetation types, the Great Basin has affinities with cold-temperate vegetation.
Dominant plant species in the region include such distinctly cold-temperate species as sagebrushes (Artemisia), saltbrushes (Atriplex), and Winter-fat (Ceratoides lanata). These scrub species are much-branched, non-sprouting, aromatic semi-shrubs with soft wood and evergreen leaves. The Great Basin also contains species with evolutionary ties to warmer climates, such as rabbitbrush (Chrysothamnus), blackbrush (Coleogyne), hopsage (grayia) and horsebrush (Tetradymia). The region, however, contains few cacti species, either in numbers of individuals or species, and also lacks most characteristic desert plants in minor drainages.
Some other notable mammals found in the Great Basin ecoregion are: Belding's ground squirrel (Spermophilus beldingi); Yellow-bellied marmot (Marmota flaviventris); Bighorn sheep (Ovis canadensis); Bushy-tailed woodrat (Neotoma cinerea); Canada lynx (Lynx canadensis); Canyon mouse (Peromyscus crinitus); Cliff chipmunk (Tamias dorsalis); Coyote (Canis latrans); Desert cottontail (Crotaphytus insularis); North American porcupine (Erethizon dorsatum).
Anuran taxa found in the Great Basin scrub steppe are eight in number: the Black toad (Anaxyrus exsul VU); Great Basin spadefoot toad (Spea intermontana); Northern leopard frog (Lithobates pipiens); Pacific treefrog (Pseudacris regilla); Northern red-legged frog (Rana aurora); Columbia spotted frog (Rana luteiventris); Southwestern toad (Anaxyrus microscaphus); and Woodhouse's toad (Anaxyrus woodhousii). The Tiger salamander (Ambystoma tigrinis) is the sole salamander found in this ecoregion.
The Great Basin holds numerous reptilian taxa: Bluntnose leopard lizard (Gambelia sila EN); Common kingsnake (Lampropeltis getula); Sierra gartersnake (Thamnophis couchii); Black-collared lizard (Crotaphytus insularis); Desert horned lizard (Phrynosoma platyrhinos); Desert spiny lizard (Sceloporus magister); Western gopher snake (Pituophis catenifer); Ground snake (Sonora semiannulata); Long-nosed leopard lizard (Gambelia wislizenii); Long-nosed snake (Rhinocheilus lecontei); Milk snake (Lampropeltis triangulum); Panamint alligator lizard (Elgaria panamintina), a California endemic found only in the following desert mountains: Panamint, Inyo, Nelson, White, Cosos and Argus; Yellow-bellied racer (Coluber constrictor); Ringneck snake (Diadophis punctatus); Sagebrush lizard (Sceloporus graciosus); Pygmy short-horned lizard (Phrynosoma douglasii); Side-blotched lizard (Uta stansburiana); Striped whipsnake (Masticophis taeniatus); Western banded gecko (Coleonyx variegatus); Western patch-nosed snake (Salvadora hexalepis); Western pond turtle (Emys marmorata); Western terrestrial garter snake (Thamnophis elegans); Tiger whiptail (Cnemidophorus tigris); Zebra-tailed lizard (Callisaurus draconoides); Rubber boa (Charina bottae); and Night snake (Hypsiglena torquata).
A large number of bird species occur within the Great Basin, either as resident or migratory taxa. Example avian species found here are: Lewis's woodpecker (Melanerpes lewis); Phainopepla (Phainopepla nitans); Pinyon jay (Phainopepla nitans VU), a specialist found in pinyon-juniper woodlands; Greater sage grouse (Centrocercus urophasianus NT); Sandhill crane (Grus canadensis).
Sierra Juarez and San Pedro Martir pine-oak forests Habitat
This taxon can be found in the Sierra Juarez and San Pedro Martir pine-oak forests. The ecoregion is located in two mountain ranges in the state of Baja California, Mexico: the Sierra de Juarez and the Sierra de San Pedro Martir. Both mountain ranges belong to the physiographical province of Baja California, and constitute the northernmost elevated peaks of the Baja Peninsula. The mountainous range that descends into a large portion of Baja California becomes more abrupt at Juarez and San Pedro Martir; the eastern slope is steeper than the western. Altitudes range between 1100-2800 meters. The granitic mountains of Juarez and San Pedro Martir have young rocky soils and are poorly developed, shallow, and low in organic matter.
Dominant trees in the ecoregion are: Pinus quadrifolia, P. jeffreyi, P. contorta, P. lambertiana, Abies concolor, and Libocedrus decurren. The herbaceous stratum is formed by Bromus sp. and Artemisia tridentata. Epiphytes and fungi are abundant throughout the forests.
Characteristic mammals of the ecoregion include: Ornate shrew (Sorex ornatus), Puma (Puma concolor), Fringed Myotis bat (Myotis thysanodes), California chipmunk (Tamias obscurus), Bobcat (Lynx rufus), Coyote (Canis latrans), San Joaquin kit fox (Vulpes macrotis) and Bighorn sheep (Ovis canadensis).
Numerous birds are present in the ecoregion, including the rare Bald eagle (Haliaeetus leucocephalus), California condor (Gymnogyps californianus), Pinyon jay (Gymnohinus cyanocephalus), and White-breasted nuthatch (Sitta carolinensis).
A number of different reptilian taxa are found in these oak-pine forests; representative reptiles here are: the Banded rock lizard (Petrosaurus mearnsi); Common checkered whiptail (Cnemidophorus tesselatus), who is found in sparsely vegetated areas; Coast horned lizard (Phrynosoma coronatum), often found in locales of sandy soil, where individuals may burrow to escape surface heat; Night desert lizard (Xantusia vigilis), who is often found among bases of yucca, agaves and cacti; and the Baja California spiny lizard (Sceloporus zosteromus).
The Pacific chorus frog (Pseudacris regilla) is an anuran found within the Sierra Juarez and San Pedro Martir pine-oak forests as one of its western North America ecoregions of occurrence. The only other amphibian in the ecoregion is the Western toad (Anaxyrus boreas).
California Central Valley Grasslands Habitat
This taxon is found in the California Central Valley grasslands, which extend approximately 430 miles in central California, paralleling the Sierra Nevada Range to the east and the coastal ranges to the west (averaging 75 miles in longitudinal extent), and stopping abruptly at the Tehachapi Range in the south. Two rivers flow from opposite ends and join around the middle of the valley to form the extensive Sacramento-San Joaquin Delta that flows into San Francisco Bay.
Perennial grasses that were adapted to cool-season growth once dominated the ecoregion. The deep-rooted Purple Needle Grass (Nassella pulchra) was particularly important, although Nodding Needle Grass (Stipa cernua), Wild Ryes (Elymus spp.), Lassen County Bluegrass (Poa limosa), Aristida spp., Crested Hair-grass (Koeleria pyramidata), Deergrass (Muhlenbergia rigens,), and Coast Range Melicgrass (Melica imperfecta) occurred in varying proportions. Most grass growth occurred in the late spring after winter rains and the onset of warmer and sunnier days. Interspersed among the bunchgrasses were a rich array of annual and perennial grasses and forbs, the latter creating extraordinary flowering displays during certain years. Some extensive mass flowerings of the California Poppy (Eschscholzia californica), Lupines (Lupinus spp.), and Exserted Indian Paintbrush (Castilleja exserta) are found in this grassland ecoregion.
Prehistoric grasslands here supported several herbivores including Pronghorn Antelope (Antilocapra americana), elk (including a valley subspecies, the Tule Elk, (Cervus elaphus nannodes), Mule Deer (Odocoileus hemionus), California ground squirrels, gophers, mice, hare, rabbits, and kangaroo rats. Several rodents are endemics or near-endemics to southern valley habitats including the Fresno Kangaroo Rat (Dipodomys nitratoides exilis), Tipton Kangaroo Rat (Dipodomys nitratoides nitratoides), San Joaquin Pocket Mouse (Perognathus inornatus), and Giant Kangaroo Rat (Dipodomys ingens). Predators originally included grizzly bear, gray wolf, coyote, mountain lion, ringtail, bobcat, and the San Joaquin Valley Kit Fox (Vulpes velox), a near-endemic.
The valley and associated delta once supported enormous populations of wintering waterfowl in extensive freshwater marshes. Riparian woodlands acted as important migratory pathways and breeding areas for many neotropical migratory birds. Three species of bird are largely endemic to the Central Valley, surrounding foothills, and portions of the southern coast ranges, namely, the Yellow-billed Magpie (Pica nuttalli), the Tri-colored Blackbird (Agelaius tricolor EN), and Nuttall’s Woodpecker (Picoides nuttallii).
The valley contains a number of reptile species including several endemic or near-endemic species or subspecies such as the San Joaquin Coachwhip (Masticophis flagellum ruddocki), the Blunt-nosed Leopard Lizard (Gambelia sila EN), Gilbert’s Skink (Plestiodon gilberti) and the Sierra Garter Snake (Thamnophis couchii). Lizards present in the ecoregion include: Coast Horned Lizard (Phrynosoma coronatum NT); Western Fence Lizard (Sceloporus occidentalis); Southern Alligator Lizard (Elgaria multicarinata); and the Northern Alligator Lizard (Elgaria coerulea).
There are only a few amphibian species present in the California Central Valley grasslands ecoregion. Special status anuran taxa found here are: Foothill Yellow-legged Frog (Rana boylii NT); Pacific Chorus Frog (Pseudacris regilla); and Western Spadefoot Toad (Pelobates cultripes). The Tiger Salamander (Ambystoma tigrinum) occurs within this ecoregion.
Although many endemic plant species are recognized, especially those associated with vernal pools, e.g. Prickly Spiralgrass (Tuctoria mucronata). A number of invertebrates are known to be restricted to California Central Valley habitats. These include the Delta Green Ground Beetle (Elaphrus viridis CR) known only from a single vernal pool site, and the Valley Elderberry Longhorn Beetle (Desmocerus californicus dimorphus) found only in riparian woodlands of three California counties.
Vernal pool communities occur throughout the Central Valley in seasonally flooded depressions. Several types are recognized including valley pools in basin areas which are typically alkaline or saline, terrace pools on ancient flood terraces of higher ground, and pools on volcanic soils. Vernal pool vegetation is ancient and unique with many habitat and local endemic species. During wet springs, the rims of the pools are encircled by flowers that change in composition as the water recedes. Several aquatic invertebrates are restricted to these unique habitats including a species of fairy shrimp and tadpole shrimp.
Sierra de la Laguna Pine-oak Forests Habitat
This taxon is found in the Sierra de la Laguna pine-oak forest, a mountainous ecoregion which rises from the arid Baja California Sur, creating islands of unique vegetative communities. There are approximately 694 plant species, approximately 85 of which are endemic to this ecoregion. Overall species richness is low to moderate, with a total of only 231 vertebrate taxa. The ecoregion is classified in the Tropical and Subtropical Coniferous Forests biome. Much of the pine-oak association remains intact due to the inaccessibility of the rugged and inaccessible terrain.
The topographical features and geological events that gave rise to this particular region are responsible for the diversity of climates and vegetation in the same area. The highest strata of mountains, situated at 1600 to 2000 metres (m) in elevation, are composed of pine-oak forests that transform into oak-pine forests (1200 m) and oak forests (800 m) as elevation decreases. The climate is temperate sub-humid with summer rains and occasional winter rains.
These pine-oak forests constitute the wettest portions in the state of Baja California Sur (760 millimetres of precipitation annually). Slight variations in climatic conditions make up three different vegetation assemblages in the temperate forest. Pine forests at the highest elevations are dominated by Pinus cembroides ssp. lagunae, and understory taxa such as Muhlenbergia spp. and Festuca spp. Pine-oak forests dominated by associations of Pinus cembroides subsp. lagunae with Quercus devia, Arbutus peninsularis, and Quercus tuberculata, and a variety of trees of smaller stature such as Calliandra peninsularis and Mimosa tricephala, with associated shrubs to complement the landscape.
Some of the endemic reptiles are the Southern Alligator Lizard (Elgaria multicarinata) and the Yucca Night Lizard (Xantusia vigilis). Other reptilian taxa found in the Sierra de la Laguna pine-oak forests include the Baja California Rock Lizard (Petrosaurus thalassinus), Baja California Rattlesnake (Crotalus enyo) and the Baja California Brush Lizard (Urosaurus nigricaudus).
Only two amphibian taxa are found in the Sierra de la Laguna pine-oak forests. The Red-spotted Toad (Anaxyrus punctatus) is one anuran found here. The widely distributed California Chorus Frog (Pseudacris cadaverina) is another resident of the ecoregion. One other anuran, Pseudacris regilla, was previously recognized in the ecoregion, but erecent DNA analysis has rendered this taxon of unclear distribution.
Of the approximately 30 mammalian species of mammals present, one of them (an endemic bat) lives only in pine-oak forests. The level of endemism is high, and this is well demonstrated by the proportion of endemic species with respect to total recorded species. More than ten percent of the mammalian species found at Sierra de la Laguna are endemic. One notable mammal found along the far west coast, including California and Baja, is the Ornate Shrew (Sorex ornatus). There are several threatened mammals found in the Sierra de la Laguna pine-oak forests, including: the Mexican Long-tongued Bat (Choeronycteris mexicana NT). The isolation of this region has contributed to the scarcity of predators, and to the poor competitive ability of some animals. Rodents and lagomorphs are virtually absent from the region
The avifauna inhabiting these pine-oak forests is important because half of the bird species breeding at Sierra de la Laguna only utilize pine-oak forests as breeding habitat. The endemic Baja Pygmy Owl (Glaucidium gnoma hoskinsii), along with the White-winged Dove (Zenaida asiatica) and Golden Eagle (Aquila chrysaetos) are only a few of the avian species found in this ecoregion. Other notable birds in this and the Gulf of California xeric scrub ecoregion include the Xantus's Hummingbird (Hylocharis xantusii) and the endangered Peninsular Yellowthroat (Geothlypis beldingi EN)..
San Lucan Xeric Scrub Habitat
This taxon is found in the San Lucan xeric scrub, an ecoregion situated at the southern-most part of the Baja Peninsula of Mexico; this diverse landscape of mountains, valleys, and plateaus is covered with a variety of species of xeric vegetation. This neotropical ecoregion is classifed within the Deserts and Xeric Scrublands biome. Plants and animals of this region evolved independently before the Baja Peninsula, a previous island during the Miocene, joined the mainland. An arid climate supports a number fauna and species, about ten percent which of which are endemic.
The ecoregion took shape in the Miocene as an isolated landform prior to joining the peninsula, and thus can be considered an biogeographical island of vegetation. This arid landscape is composed of a vast, rugged complex of granitic mountains, valleys, canyons, and plateaus. The ecoregion occupies the plateaus between the coast and the lower limits of the dry forests, which begin around 250 meters. Precipitation is about 400 millimetres annually.
Some elements of dry forest habitat are present in this ecoregion, but xeric elements are dominant and include Chain-link Cholla (Opuntia cholla); Elephant Tree (Bursera microphylla), at the southern limit of its range here and extending north to the Waterman Mountains in the USA; Mauto (Lysiloma divaricata); Organ Pipe Cactus (Stenocereus thuberi), Mala Mujer (Cnidoscolus angustidens), Yucca spp., and Barrel Cacti (Ferocactus spp). Herbaceous elements in the ecoregion include Plantago linearis, Bouteloua hirsuta, and Commelina coelestis.
The San Lucan xeric scrub harbours 31 of 48 of the reptile species for the Cape Region. Almost a third of the wider regional recorded species of collembola arthropods and spiders (30 of 138 species, respectively) occur in this ecoregion. In general, over ten percent of animal and plant species found here are endemic.
Within the San Lucan xeric scrub ecoregion, reptilian taxa include: the endemic Island Burrowing Sand Snake (Chilomeniscus punctatissimus); the endemic Isla Cerralvo Snake (Chilomeniscus savagei), restricted solely to Cerralvo Island; the Cape Arboreal Spiny Lizard (Sceloporus licki), a near-endemic restricted to the southern portion of the Baja Peninsula; the near-endemic Spiny Chuckwalla (Sauromalus hispidus NT), found only on Angel de la Guarda Island, Granito, Mejía, Pond, San Lorenzo Norte, San Lorenzo Sur, and other islands in Bahía de los Ángeles, including Cabeza de Caballo, La Ventana, Piojo, Flecha, Mitlàn, and Smith, Gulf of California; the near-endemic San Lucan Leaf-toed Gecko (Phyllodactylus unctus NT), found only on southern Baja Peninsula and some islands within the Gulf of California: Gallo, Partida Sur, Espiritu Santo, Ballena, Gallina and Cerralvo. There are only a small number of anuran species present in the ecoregion: Red-spotted Toad (Anaxyrus punctatus); and Pacific Chorus Frog (Pseudacris regilla).
The Espiritu Santo Island Antelope Squirrel (Ammospermophilus insularis) is endemic to the San Lucan xeric scrub ecoregion and is found only on the island of Espiritu Santo in the Gulf of California. Among threatened mammals occurring in the ecoregion are: the near-endemic Dalquest's Pocket Mouse (Chaetodipus dalquesti VU), known from the Cape Region of the Baja California Peninsula.
Threatened mammals in the ecoregion include: the near-endemic Peninsular Myotis (Peninsular Myotis EN), found only on southern Baja Peninsula; Fish-eating Bat (Myotis vivesi VU), a near-endemic occurring chiefly on the near-shore islands off of the southern Baja Peninsula and mainland Sonora; Mexican Long-tongued Bat (Choeronycteris mexicana NT); and the Lesser Long-nosed Bat (Leptonycteris yerbabuenae VU).
Baja California Desert Habitat
This taxon is found in the Baja California Desert ecoregion, located on most of the western side of the Baja Peninsula, containing varied habitats such as mountains, plains and coastal dunes. This desert is one of the largest and best preserved in Mexico, and due to its isolation, contains a high level of species richness and endemism. A series of ophiolytes (formations of gabrum, ultramafic rocks, and volcanic lava) surround the most prominent orographic feature: The San Andres mountain range. Overall, the climate is arid with variable temperature. The isolated nature of the peninsula, and its proximity to the sea, maintains a measure of humidity, and creates a stable diurnal temperature.
The predominant vegetation associations are composed of xeric scrub, which have been subdivided in diverse categories according to dominant species and the ecological conditions in which they occur. Thick-stemmed trees and shrubs, growing on rocky volcanic soils, cover the highest parts of the mountain ranges. Dominant plant species are Ambrosia camphorata, Common Stork's-bill (Erodium cicutarium), and Astragalus prorifer. The Boojumtree (Fouquieria columnaris) can be also found at elevations up to 1200m. Many species of cacti are present. Dominant species within the Baja California Desert vary with elevation. Epiphytes such as Small Ballmoss (Tillandsia recurvata) and Cudbear (Rocella tinctoria) grow in low elevation, humid areas, and account for a majority of the perennial vegetation. Areas previously submerged under the sea (in the Miocene era) are now covered by highly saline and alkaline-tolerant species, such as Ambrosia magdalenae, El Vizcaino Agave (Agave vizcainoensis), Datilillo (Yucca valida), Pitaya Agria (Stenocereus gummosus), and Porter's Muhly (Muhlenbergia porteri). Dune vegetation includes Creosote Bush (Larrea tridentata), Barclay's Saltbush (Atriplex barclayana), Rush Milkweed (Asclepias subulata) and Nicolletia trifida.
There are a number of reptilian taxa found in the Baja California Desert including the endemic Baja California Brush Lizard (Urosaurus lahtelai). The Baja California Legless Lizard (Anniella geronimensis EN) is also endemic to the ecoregion, and is restricted to a narrow strip around 87 kilometres (km) long, ranging from about six km north of Colonia Guerrero, southerly to a point south of Punta Baja at the northern edge of Bahia El Rosario. This legless lizard extends to at most four km inland in the Arroyo Socorro, but otherwise found only in the coastal zone; A. geronimensis also occurs on Isla San Gerónimo. Also found here is the San Lucan Leaf-toed Gecko (Phyllodactylus unctus NT), a species not endemic to the ecoregion, but restricted to the southern Baja Peninsula and the Gulf of California islands of Partida Sur, Gallo, Espiritu Santo, Ballena, Gallina and Cerralvo.
There are only a few amphibians found in the ecoregion. Anuran taxa occurring here include: California Chorus Frog (Pseudacris cadaverina); Pacific Chorus Frog (Pseudacris regilla); and Canyon Treefrog (Hyla arenicolor). Also found here is the Plateau Toad (Anaxyrus compactilis), an endemic to the lower central Mexican Plateau and Baja California Desert; another toad occurring in the ecoregion is the Western Toad (Anaxyrus boreas NT). The Channel Islands Slender Salamander (Batrachoseps pacificus) was earlier thought to occur in this ecoregion, but genetic data shows that this taxon is strictly endemic to the Channel Islands of California.
Endemic mammals include San Quintín Kangaroo Rat (Dipodomys gravipes CR), and Baja California Rock Squirrel (Spermophilus atricapillus EN). Other mammals that are classified as special status are the Lesser Long-nosed Bat (Leptonycteris yerbabuenae VU). Some shallow coastal saltwater lagoons protruding into the Baja California Desert along the Pacific Ocean provide key breeding habitat for the Grey Whale (Eschrichtius robustus CR). One of the largest such breeding waters is the remote San Ignacio Lagoon, extending many kilometres inland and rarely exceeding fifteen metres in depth.
Important sites for avian conservation include the Ojo de Liebre lagoon, along the Pacific coast, which is home to millions of overwintering ducks and geese. Bird species in the Baja California Desert include such notable raptor taxa as Golden Eagle (Aquila chrysaetos), Peregrine Falcon (Falco peregrinus), Southern Crested Caracara (Caracara plancus), Osprey (Pandion haliaeutus), and Burrowing Owl (Athene cunicularia).
Palouse Grasslands Habitat
This taxon is found in the Palouse grasslands, among other North American ecoregions. The Palouse ecoregion extends over eastern Washington, northwestern Idaho and northeastern Oregon. Grasslands and savannas once covered extensive areas of the inter-mountain west, from southwest Canada into western Montana in the USA. Today, areas like the great Palouse prairie of eastern are virtually eliminated as natural areas due to conversion to rangeland. The Palouse, formerly a vast expanse of native wheatgrasses (Agropyron spp), Idaho Fescue (Festuca idahoensis), and other grasses, has been mostly plowed and converted to wheat fields or is covered by Drooping Brome (Bromus tectorum) and other alien plant species.
the Palouse historically resembled the mixed-grass vegetation of the Central grasslands, except for the absence of short grasses. Such species as Bluebunch Wheatgrass (Elymus spicatus), Idaho Fescue (Festuca idahoensis) and Giant Wildrye (Elymus condensatus) and the associated species Lassen County Bluegrass (Poa limosa), Crested Hairgrass (Koeleria pyramidata), Bottlebrush Squirrel-tail (Sitanion hystrix), Needle-and-thread (Stipa comata) and Western Wheatgrass (Agropyron smithii) historically dominated the Palouse prairie grassland.
Representative mammals found in the Palouse grasslands include the Yellow-bellied Marmot (Marmota flaviventris), found burrowing in grasslands or beneath rocky scree; American Black Bear (Ursus americanus); American Pika (Ochotona princeps); Coast Mole (Scapanus orarius), who consumes chiefly earthworms and insects; Golden-mantled Ground Squirrel (Spermophilus lateralis); Gray Wolf (Canis lupus); Great Basin Pocket Mouse (Perognathus parvus); Northern River Otter (Lontra canadensis); the Near Threatened Washington Ground Squirrel (Spermophilus washingtoni), a taxon who prefers habitat with dense grass cover and deep soils; and the Northern Flying Squirrel (Glaucomys sabrinus), a mammal that can be either arboreal or fossorial.
There are not a large number of amphibians in this ecoregion. The species present are the Great Basin Spadefoot Toad (Spea intermontana), a fossorial toad that sometimes filches the burrows of small mammals; Long-toed Salamander (Ambystoma macrodactylum); Northern Leopard Frog (Glaucomys sabrinus), typically found near permanent water bodies or marsh; Columbia Spotted Frog (Rana luteiventris), usually found near permanent lotic water; Pacific Treefrog (Pseudacris regilla), who deposits eggs on submerged plant stems or the bottom of water bodies; Tiger Salamander (Ambystoma tigrinum), fossorial species found in burrows or under rocks; Woodhouse's Toad (Anaxyrus woodhousii), found in arid grasslands with deep friable soils; Western Toad (Anaxyrus boreas), who uses woody debris or submerged vegetation to protect its egg-masses.
There are a limited number of reptiles found in the Palouse grasslands, namely only: the Northern Alligator Lizard (Elgaria coerulea), often found in screes, rock outcrops as well as riparian vicinity; the Painted Turtle (Chrysemys picta), who prefers lentic freshwater habitat with a thick mud layer; Yellow-bellied Racer (Chrysemys picta); Ringneck Snake (Diadophis punctatus), often found under loose stones in this ecoregion; Pygmy Short-horned Lizard (Phrynosoma douglasii), a fossorial taxon often found in bunchgrass habitats; Side-blotched Lizard (Uta stansburiana), frequently found in sandy washes with scattered rocks; Southern Alligator Lizard (Elgaria multicarinata), an essentially terrestrial species that prefers riparian areas and other moist habitats; Pacific Pond Turtle (Emys marmorata), a species that usually overwinters in upland habitat; Western Rattlesnake (Crotalus viridis), who, when inactive, may hide under rocks or in animal burrows; Night Snake (Hypsiglena torquata); Western Skink (Plestiodon skiltonianus), who prefers grasslands with rocky areas; Western Terrestrial Garter Snake (Thamnophis elegans), found in rocky grasslands, especially near water; Rubber Boa (Charina bottae).
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
Habitat and Ecology
Central Pacific Coastal Forests Habitat
This taxon is found in the Central Pacific Coastal Forests ecoregion, as one of its North American ecoregions of occurrence. These mixed conifer rainforests stretch from stretch from southern Oregon in the USA to the northern tip of Vancouver Island, Canada. These forests are among the most productive in the world, characterized by large trees, substantial woody debris, luxuriant growths of mosses and lichens, and abundant ferns and herbs on the forest floor. The major forest complex consists of Douglas-fir (Pseudotsuga menziesii) and Western hemlock (Tsuga heterophylla), encompassing seral forests dominated by Douglas-fir and massive old-growth forests of Douglas-fir, Western hemlock, Western red cedar (Thuja plicata), and other species. These forests occur from sea level up to elevations of 700-1000 meters in the Coast Range and Olympic Mountains. Such forests occupy a gamut of environments with variable composition and structure and includes such other species as Grand fir (Abies grandis), Sitka spruce (Picea sitchensis), and Western white pine (Pinus monticola).
Characteristic mammalian fauna include Elk (Cervus elaphus), Black-tailed Deer (Odocoileus hemionus), Coyote (Canis latrans), Black Bear (Ursus americanus), Mink (Mustela vison), and Raccoon (Procyon lotor).
The following anuran species occur in the Central Pacific coastal forests: Coastal tailed frog (Ascaphus truei); Oregon spotted frog (Rana pretiosa VU); Northern red-legged frog (Rana pretiosa); Pacific chorus frog (Pseudacris regilla); Cascade frog (Rana cascadae NT), generally restricted to the Cascade Range from northern Washington to the California border; Foothill yellow-legged frog (Rana boylii) and the Western toad (Anaxyrus boreas NT). A newt found in the ecoregion is the Rough skinned newt (Taricha granulosa).
Salamanders within the ecoregion are: Del Norte salamander (Plethodon elongatus NT); Van Dyke's salamander (Plethodon vandykei); Western redback salamander (Plethodon vehiculum); Northwestern salamander (Ambystoma gracile); Olympic torrent salamander (Rhyacotriton olympicus VU), whose preferred habitat is along richly leafed stream edges; Long-toed salamander (Ambystoma macrodactylum), whose adults are always subterranean except during the breeding season; Dunn's salamander (Plethodon dunni), usually found in seeps and stream splash zones; Clouded salamander (Aneides ferreus NT), an aggressive insectivore; Monterey ensatina (Ensatina eschscholtzii), usually found in thermally insulated micro-habitats such as under logs and rocks; Pacific giant salamander (Dicamptodon tenebrosus), found in damp, dense forests near streams; and Cope's giant salamander (Dicamptodon copei), usually found in rapidly flowing waters on the Olympic Peninsula and Cascade Range.
There are a small number of reptilian taxa that are observed within this forested ecoregion, including: Pacific pond turtle (Emys marmorata); Common garter snake (Thamnophis sirtalis), an adaptable snake most often found near water; Northern alligator lizard (Elgaria coerulea); and the Western fence lizard.
Numerous avian species are found in the ecoregion, both resident and migratory. Example taxa occurring here are the Belted kingfisher (Megaceryle alcyon); Wild turkey (Meleagris gallopavo); and the White-headed woodpecker (Picoides albolarvatus) and the Trumpeter swan (Cygnus buccinator), the largest of the North American waterfowl.
Comments: Pacific treefrogs occupy a wide variety of habitats, including grassland, chaparral, woodland, forest, and farmland. They live on land except during the breeding season. Females deposit eggs in shallow water of marshes, lakes, ponds, ditches, reservoirs and slow-moving streams (Stebbins 2003), sometimes in weakly brackish water (Gardner, 1995, Herpetological Review 26:32).
Pacific treefrogs spend most of their time on the ground, but after the breeding season they commonly bask on the leaves of broad-leaved evergreen shrubs far from water, and sometimes they climb high into trees.
See Munger et al. (1998) for quantitative information on habitat in southwestern Idaho.
Mojave Desert Habitat
This taxon is found in the Mojave Desert, the smallest of the four North American deserts. While the Mojave lies between the Great Basin Shrub Steppe and the Sonoran Desert, its fauna is more closely allied with the lower Colorado division of the Sonoran Desert. Dominant plants of the Mojave include Creosote Bush (Larrea tridentata), Many-fruit Saltbush (Atriplex polycarpa), Brittlebush (Encelia farinosa), Desert Holly (Atriplex hymenelytra), White Burrobush (Hymenoclea salsola), and Joshua Tree (Yucca brevifolia), the most notable endemic species in the region.
The Mojave’s warm temperate climate defines it as a distinct ecoregion. Mojave indicator species include Spiny Menodora (Menodora spinescens), Desert Senna (Cassia armata), Mojave Indigobush (Psorothamnus arborescens), and Shockley's Goldenhead (Acamptopappus shockleyi). The Mojave supports numerous species of cacti, including several endemics, such as Silver Cholla (Opuntia echinocarpa), Mojave Prickly Pear (O. erinacea), Beavertail Cactus (O. basilaris), and Cotton-top Cactus (Echinocactus polycephalus).
While the Mojave Desert is not so biologically distinct as the other desert ecoregions, distinctive endemic communities occur throughout. For example, the Kelso Dunes in the Mojave National Preserve harbor seven species of endemic insects, including the Kelso Dunes Jerusalem Cricket (Ammopelmatus kelsoensis) and the Kelso Dunes Shieldback Katydid (Eremopedes kelsoensis). The Mojave Fringe-toed Lizard (Uma Scoparia), while not endemic to the dunes, is rare elsewhere. Flowering plants also attract butterflies such as the Mojave Sooty-wing (Pholisora libya), and the widely distributed Painted Lady (Vanessa cardui).
There are a total of eight amphibian species present in the Mojave Desert all of which are anuran species: the endemic Relict Leopard Frog (Lithobates onca); the endemic Amargosa Toad (Anaxyrus nelsoni); Lowland Leopard Frog (Lithobates yavapaiensis); Red-spotted Toad (Anaxyrus punctatus); Southwestern Toad (Anaxyrus microscaphus); Great Basin Spadefoot (Spea intermontana); Great Plains Toad (Anaxyrus cognatus); and the Pacific Treefrog (Pseudacris regilla).
The native range of California’s threatened Desert Tortoise (Gopherus agassizii) includes the Mojave and Colorado Deserts. The Desert Tortoise has adapted for arid habitats by storing up to a liter of water in its urinary bladder. The following reptilian fauna are characteristic of the Mojave region in particular: Gila Monster (Heloderma suspectum NT); Western Banded Gecko (Coleonyx variegatus), Northern Desert Iguana (Dipsosaurus dorsalis), Western Chuckwalla (Sauromalus obesus), and regal horned lizard (Phrynosoma solare). Snake species include the Desert Rosy Boa (Charina trivirgata gracia), Mojave Patchnose Snake (Salvadora hexalepis mojavensis), and Mojave Rattlesnake (Crotalus scutulatus).
Endemic mammals of the ecoregion include the Mojave Ground Squirrel (Spermophilus mohavensis) and Amargosa Vole (Microtus californicus scirpensis); and the California Leaf-nosed Bat (Macrotus californicus).
Non-Migrant: No. All populations of this species make significant seasonal migrations.
Locally Migrant: No. No populations of this species make local extended movements (generally less than 200 km) at particular times of the year (e.g., to breeding or wintering grounds, to hibernation sites).
Locally Migrant: No. No populations of this species make annual migrations of over 200 km.
Individuals migrate up to several hundred meters between breeding sites and nonbreeding upland habitats.
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)
Comments: Known to eat beetles, flies, spiders, ants, and ispopods, etc. Larvae scape periphyton off rocks, eat filamentous algae and epiphytic diatoms in floating mats, bottom feed on benthic detritus, and surface feed on films of diatoms and pollen (Kupferberg et al., Copeia 1994:446-457).
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.
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.
- garter snakes (Thamnophis elegans)
- mosquitofish (Gambusia affinis)
Anti-predator Adaptations: cryptic
Weitzel and Panik (1993) reported on a northwestern Nevada population that exibited long-term persistence despite periodic catastrophic flooding and stream dry-ups that prevented successful reproduction in some years.
Larvae are preyed upon by carnivorous aquatic insects, bullfrogs, garter snakes, and many birds and mammals. Important predators on adults include garter snakes.
Life History and Behavior
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
Comments: Like many terrestrial amphibians, these frogs are inactive during freezing weather and extreme drought.
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
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.
Status: captivity: 9 (high) years.
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
Breeding occurs generally in winter or spring (sometimes in summer), with the earliest breeding occurring in lowland areas in the southern part of the range: mid-May to early August in northern California, January-June in southern California, late April-early May in northern Idaho. Eggs are laid in packets of about 20-80, hatch in 3-5 weeks in western Oregon. Larvae metamorphose into tiny frogs within about 2-3 months. In northern Idaho, metamorphosis occurred in mid- to late summer (Schaub and Larsen 1978). Most breeders are at least 2 years old, but some individuals may mature in less than 1 year in western Oregon (Nussbaum et al. 1983). Multiple clutches per year have been documented in southern California (Perrill and Daniel 1983).
Calling frequently occurs outside the breeding season and far away from breeding sites.
Molecular Biology and Genetics
Barcode data: Pseudacris regilla
Below is the sequence of the barcode region Cytochrome oxidase subunit 1 (COI or COX1) from a member of the species.
See the BOLD taxonomy browser for more complete information about this specimen.
Other sequences that do not yet meet barcode criteria may also be available.
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Download FASTA File
Statistics of barcoding coverage: Pseudacris regilla
Public Records: 1
Specimens with Barcodes: 7
Species With Barcodes: 1
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
IUCN Red List Assessment
Red List Category
Red List Criteria
National NatureServe Conservation Status
Rounded National Status Rank: N5 - Secure
Rounded National Status Rank: N5 - Secure
NatureServe Conservation Status
Rounded Global Status Rank: G5 - Secure
Intrinsic Vulnerability: Moderately vulnerable
Environmental Specificity: Moderate to broad.
Life History, Abundance, Activity, and Special Behaviors
Breeding: H. regilla breeds over a long period of time, from January to the middle of May, in marshes, ponds, lakes, reservoirs, roadside ditches, and slow streams (Stebbins 1985). In interior British Colombia, it may breed in June and July also. Later breeding occurs in higher altitudes. Around January, at the beginning of the breeding season, large numbers of vociferous males congregate at transient rain pools and more permanent bodies of water. The females do not enter the water until later, when they are ready to lay. Usually, females enter in the late afternoon or early evening, and mating and egg laying usually occurs by the following morning. Females enter either by themselves or in small groups, so there are many more males than females, making immediate mating probable. Usually, there is a preliminary period of clasping that lasts anywhere from 4 to 24 hours in a laboratory, and probably about 4 to 10 hours in nature. The male tightly grips the female with is forelimbs, but does not contact her with his body behind his pectoral region except when inseminating eggs. The males legs are flexed in a sitting pose, and insemination occurs at the moment of the extrusion of the eggs. The male discharges a quantity of transparent semen by bringing his cloacal aperture close to that of the female. With a quick, firm extension, the male slides his feet posteriorly over the sides and hips of the female, then retracts to his previous position. Simultaneously, the female extrudes a clutch of eggs into the cloud of sperm. The female sometimes scratches the substratum on which the eggs are going to be deposited before releasing the eggs. As the female extrudes the eggs, her cloaca is brought close to this surface and their attachment is effected. The eggs may be removed from her cloaca by her tarsi through flexor-extensor reflexes. The interval between layings is usually 2 to 10 minutes, but could be longer. After oviposition, the frogs separate. Amplexus is pectoral, and may last from 8 to 40 hours or longer (Smith 1940).
Eggs: Clusters of eggs are deposited in a ponds shallow water, usually at depths above 4 inches. The clusters can be attached to sticks, leaves, vegetation, or other objects, and they can also be found floating on the surface, usually attached to objects. Eggs are usually laid in loose clusters of irregular shape, and the cluster has 2 gelatinous envelopes. The outer envelope is 4.78 to 6.7 mm and is sticky, and the inner envelope is 1.88 to 2.70 mm. Each packet usually has 22 to 25 eggs, but could have anywhere from 5 to 60 eggs. As the layings near an end, the number of eggs per clutch can decrease to 3 or 4, or even single eggs (Livezey and Wright 1947).
Larva: The tadpole is about 45 mm long, full and deep-bodied, and has a fairly long tail, about 2 times the head and body length. The labial tooth row formula is 2/3, and the spiracle is sinistral, directed posteriorly (Grismer 2002). The general color is blackish and yellowish brown to dark brown with heavy black spots. Below, it is whitish with bronze or copper tinges. The tail is mottled with black, and the iris is golden, with a darker area anterior and posterior to the pupil (Stebbins 1951).
Call: H. regilla is the most commonly heard frog species on the Pacific coast. The calls last for about 1 second and are often uttered in sequence. Each 1-second call consists of a loud, two-parted 'kreck-ek', with rising inflection in the last syllable. H. regilla has a round vocal sac (Stebbins 1985). While singing, a male may float with his limbs outstretched and his globular pouch extended to or beyond his chin (Stebbins 1951).
Food: H. regilla eats insects, including leaf-hoppers, spring-tails, flies, stoneflies, ants, wasps, beetles, and caterpillars, It also eats spiders, isopods, and snails (Stebbins 1972).
Behavior: H. regilla is mainly nocturnal, but it is also active in the daytime. Sometimes, at low elevations, it is active throughout the year. It is a good climber, but usually stays near the ground. It has a great capacity for color change, and a change from an unspotted dark coloration through a medium light colored phase with spots to an unspotted light phase may take about 8 to 10 minutes (Stebbins 1951).
Degree of Threat: Medium
Comments: Introduced mosquitofish (GAMBUSIA AFFINIS) prey heavily on larvae and may negatively affect P. REGILLA populations (Goodsell and Kats 1999). However, this is not a pervasive threat. In lakes in the Sierra Nevada, H. regilla distribution and abundance were negatively related to non-native trout presence (Matthews et al. 2001).
Relevance to Humans and Ecosystems
There are no known adverse effects of Pseudacris regilla on humans.
As an insectivore, Pseudacris regilla likely helps control insect pest species throughout their geographic range.
Positive Impacts: controls pest population
Pacific tree frog
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The Pacific tree frog (Pseudacris regilla), also known as the Pacific chorus frog, has a range from the West Coast of the United States (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.
The naming of this frog has a very confusing history. First, the frog was moved from the genus Hyla to the genus Pseudacris in 1986. Then, in 2006, Recuero et al. split the frog into three species. Recuero et al. attached the name Pseudacris regilla with the central component, Pseudacris hypochondriaca with southern (Baja Californian) component, and Pseudacris pacifica with northern component. However, if this split is accepted, the correct name (i.e., the oldest available name) for the northern component is Pseudacris regilla and for the central one Pseudacris sierra. This revision remains controversial. The Amphibian Species of the World 6.0 recognizes the split, but uses the name Pseudacris regilla for the northern component, the definition followed in this article.
Anatomy and morphology
The Pacific tree frog grows up to 2 in 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.
Distribution, habitat and ecology
Pacific tree frogs are common on the Pacific coast of Oregon and Washington, but they are found from extreme northern California to British Columbia. A small population also exists in a pond on Revillagigedo Island near Ketchikan, Alaska, having been intentionally introduced there in the 1960s. 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 and other amphibians.
Reproduction, development and behavior
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, calling "ooh-yeeh" or ribbiting loudly. 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.
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 are 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 9 years in captivity.
They produce several call types. 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.
Green and brown color morphs
One of the most interesting features of these frogs is their ability to change color from brown to green. Previously, adults were thought to occur in two different fixed colors. 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. 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.  This mutation might inhibit the xanthophores' ability to produce yellow pigments, thus the normally green frog (possibly of the color-unchanging type) appears blue.
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.
These frogs 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. 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.
- Geoffrey Hammerson, Georgina Santos-Barrera (2004). "Pseudacris regilla". IUCN Red List of Threatened Species. Version 2014.2. International Union for Conservation of Nature. Retrieved 3 September 2014.
- Frost, Darrel R. (2014). "Pseudacris regilla (Baird and Girard, 1852)". Amphibian Species of the World: an Online Reference. Version 6.0. American Museum of Natural History. Retrieved 3 September 2014.
- Recuero, Ernesto; Martínez-Solano, Íñigo; Parra-Olea, Gabriela; García-París, Mario (2006). "Phylogeography of Pseudacris regilla (Anura: Hylidae) in western North America, with a proposal for a new taxonomic rearrangement". Molecular Phylogenetics and Evolution 39 (2): 293–304. doi:10.1016/j.ympev.2005.10.011.
- Dodd, C. K., Jr. 2013. Frogs of the United States and Canada. Volume 1. xxxi + 460.
- S.O. MacDonald. "Pacific Chorus Frog". The Amphibians and Reptiles of Alaska. A Field Handbook. Retrieved 3 September 2014.
- C. Michael Hogan (2008) Rough-skinned Newt (Taricha granulosa), Globaltwitcher, ed. Nicklas Stromberg
- Hallock, L.A. and McAllister, K.R. (February 2005). "Pacific Treefrog". Washington Sate Department of Natural Resources. Retrieved 11 January 2013.
- Jameson, David L. 1957. Population structure and homing responses in the Pacific Tree Frog. American Society of Ichthyologist and Herpetologists. Copeia. 1957 No. 3 pp. 221–228
- Symbols of Washington State
Names and Taxonomy
Comments: Recuero et al. (2006) examined patterns of mtDNA variation (including new samples and additional samples presented by Ripplinger and Wagner 2004) and reviewed available allozyme data for Pseudacris regilla (sensu lato). They concluded that P. regilla should be partitioned into three species, P. regilla, P. sierra, and P. hypochondriaca (the original proposal included different names based on taxonomic errors that were subsequently corrected). The authors did not provide detailed maps or descriptions of the ranges of the three proposed species and did not describe the contact zones between P. sierra and the other two species.
This species formerly was included in the genus Hyla; it was transferred to the genus Pseudacris by Hedges (1986), based on allozyme data (see also Highton 1991). Cocroft (1994) analyzed morphological and biochemical data and concluded that the Hyla regilla-Hyla cadaverina clade does not arise within the clade containing Pseudacris (traditional sense), P. ocularis, and P. crucifer; he suggested that the most conservation approach may be to leave regilla and cadaverina in the genus Hyla until their relationships are more clearly resolved. da Silva (1997) recommended that for now Hedges' (1986) definition of Pseudacris should be maintained.
Highton (2000) reviewed available allozyme data from Case et al. (1975) and concluded that P. regilla likely encompasses more than one species but that further range-wide study is needed to clarify the situation.
A molecular phylogeny of Pseudacris based on mtDNA data (Moriarty and Cannatella 2004) revealed four strongly supported clades within Pseudacris: (1) A West Coast Clade containing regilla and cadaverina, (2) a Fat Frog Clade including ornata, streckeri, and illinoensis, (3) a Crucifer Clade consisting of crucifer and ocularis, and (4) a Trilling Frog Clade containing all other Pseudacris. Within the Trilling Frog Clade, brimleyi and brachyphona form the sister group to the Nigrita Clade: nigrita, feriarum, triseriata, kalmi, clarkii, and maculata. The Nigrita Clade shows geographic division into three clades: (1) populations of maculata and triseriata west of the Mississippi River and Canadian populations, (2) southeastern United States populations of feriarum and nigrita, and (3) northeastern United States populations of feriarum, kalmi, and triseriata. Current taxonomy does not reflect the phylogenetic relationships among populations of the Nigrita Clade (Moriarty and Canatella 2004). For example, the molecular data appear to indicate that triseriata, maculata, and clarkii in the western United States are conspecific, but the authors indicated that further sampling and analysis of the Trilling Frog Clade are needed before their relationships can be determined and an appropriate taxonomy established. Moriarty and Cannatella (2004) found that subspecific epithets for crucifer (crucifer and bartramiana) and nigrita (nigrita and verrucosa) are uninformative, and they therefore discouraged recognition of these subspecies. They concluded that further study is needed to determine if illinoensis warrants status as a distinct species. Molecular data were consistent with retention of regilla, cadaverina, ocularis, and crucifer in the genus Pseudacris.