Pseudacris regilla

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. 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. 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. 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. 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)