San Diego Natural History Museum--Your Nature ConnectionSDNHM Field Guide
Pacific Treefrog, by Bradford Hollingsworth.

Pseudacris regilla
Pacific Treefrog

HYLIDAE

Video  See Pacific Treefrog Calling video clip (2.70MB).

Pseudacris is from the Greek pseudes, meaning false or deceptive, and acris, from the Greek akris, meaning a locust. This name is presumably in reference to their voice. The species name regilla is from the Latin regillus, meaning regal or splendid. Some researchers place this species in the genus Hyla.

Description

These small frogs range in size from 3/4 to 1 inch and have slightly expanded toe pads. They have a dark brown to black eye stripe which disrupts the outline of the eye. Their dorsal color pattern is highly variable ranging from unicolor to mottled with greens, tans, reds, grays, browns, or blacks. They have the ability to change from light to dark. Many individuals have a dark triangular mark on their head. In males, the throat is dusky colored and wrinkled. When calling, the vocal sac expands the throat into a round balloon-like membranous pouch.

Tadpoles have a round body, longer than wide, with eyes slightly protruding. Their tail has a fin only slightly higher than the body. The mouth is square with two denticle rows on the top and three on the bottom. Larger tadpoles are mottled with dark brown to black markings on a lighter brown to golden background. Shiny spots or a sheen is present along the sides. The belly is white.

Range and Habitat

Pacific Treefrog, by Bradford Hollingsworth.

The Pacific Treefrog ranges from British Columbia, Canada to the tip of Baja California, México and eastward to Montana and Nevada. In central Baja California, the distribution of the Pacific Treefrog is restricted to desert oases. The Pacific Treefrog is the only native frog species on the Channel Islands.

This species is found in a wide range of habitats from sea level to the tops of mountains. In our region, it is found in grasslands, chaparral, woodland, desert oases, agricultural regions, and residential areas.

Natural History

This is the most common frog in our region and can be found in a wide variety of habitats. Despite the name Treefrog, this species is predominantly terrestrial, living in or near moist environoments. The call of the male Pacific Treefrog is the most common frog call heard in our region and possibly the entire world since it is often heard in Hollywood movies and television shows. The Pacific Treefrog is most closely related to the California Treefrog (Pseudacris cadaverina).

Behavior: This frog is chiefly nocturnal, spending the day beneath logs, rocks, or other debris. During breeding season, males will call to attract females. A number of calling males is known as a chorus. A dominant male, or chorus master, leads off the calling which is then followed by subordinate males. If an intruding male comes instead, the Pacific Treefrog changes its usual two-part "ribbet" to a one-part encounter call. An observer trying to locate the Pacific Treefrog can mimic their calls and take over as chorus master, enticing the other frogs to begin calling as well. If this is done, be prepared to take on the responsibilities that come with being the chorus master!

Breeding: The Pacific Treefrog breeds from November to July in a wide array of habitats including marshes, ponds, lakes, ditches, and slow-moving streams. Egg clusters are attached to sticks or vegetation and may contain as many as 70 eggs per cluster. In shallower water, eggs will be deposited on the bottom. Tadpoles, or larvae, hatch within a week and metamorphosis may take up to 2 1/2 months.

Voice: A loud, two-part "kreck-eck" with the last syllable rising in inflection serves as their advertisement call.

Prey and Predators: The Pacific Treefrog eats a wide variety of arthopods. A number of predators rely on the Pacific Treefrog as a food source, garter snakes being the most noteworthy.

Conservation Status

There have been no proposed conservation plans.

Suggested Reading

Stebbins, R.C. and N.W. Cohen. 1995. A natural history of amphibians. Princeton University Press. 316 p.

Jameson, D.L., J.P. Mackey, and R.C. Richmond. 1966. The systematics of the Pacific tree frog, Hyla regilla. Proceedings of the California Academy of Scienices, 19:551-620.

Gaudin, A.J. 1965. Larval development of the Tree Frogs Hyla regilla and Hyla californiae. Herpetologica 21:117-130.


Text by Bradford Hollingsworth and Kathy Roberts
Photo credit: Bradford Hollingsworth

Field Guide: Reptiles and Amphibians | Field Guide Feedback Form