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Pacific Treefrog (Pacific Chorus Frog)

Pacific tree frog

Pacific Treefrog
© 2010 Alf Fengler

Scientific name: Pseudacris regilla. The genus name Pseudacris is derived from the Greek word pseudes, meaning false, and akris, meaning locust. This is a reference to the treefrogs’ voice. The species name regilla is from the Latin word regillus, meaning regal or splendid.

Appearance and size: Pacific Treefrogs come in many shades of green or brown and can change their skin colors based on light and heat. All have a dark stripe through each eye. Pacific Treefrogs usually grow up to 0.5 – 1.75 inches from snout to vent.

Habitat: Found in wetlands, ponds, and rivers of coniferous forests, oak woodland chaparral and grassland.

Range: Throughout the states of California, Oregon, Washington, and British Columbia.

Life cycle: Pacific Treefrogs breed from February to August. The tadpoles metamorphose into tiny froglets within 3 months after hatching. On average, Pacific Treefrogs live up to 5-7 years in the wild. In captivity, they have been known to live for 9 years.

Voice: The males’ breeding call is a 2-note “kreck-ek” or “ribbit” sound.

Predators: Predators include snakes, raccoons, river otters, and bullfrogs.

Pacific Treefrogs at Edgewood

Pacific Treefrogs in breeding amplexus

Pacific tree frogs in breeding amplexus (mating position) in late February in Alameda County © 2013 M. James

  1. Where at Edgewood am I likely to see or hear Pacific Treefrogs? In creeks and vernal pools (temporary ponds). They are most frequently heard along the upper Clarkia Trail above the creek in the eastern canyon.
  2. What are their calls like? Pacific Treefrogs’ calls are a high-pitch 2-note “kreck-eck” or ribbit sound. Calls can be made at any time of the day, but large choruses are most common when it gets dark. Males also sometimes make a one-note aggressive “krrreck” sound if one frog gets to close to another in the breeding pond. More about calls.
  3. How does their life cycle fit in with our seasons? As the wet season warms up in February, Pacific Treefrogs start breeding. The ponds contain numerous egg masses and tadpoles until April, when most tadpoles start to grow legs and develop. The small Pacific Treefrogs tadpoles metamorphose into tiny frogs by late June, and juvenile frogs occur in the surrounding areas throughout the rest of summer.
  4. What times of day and year can I hear them? Pacific Treefrogs are active both day and night. Large choruses of their calls are most common around sunset. Their calls are best heard in their breeding season from February to June, although there might be smaller vocalizations on milder days in winter.
  5. What do they do in the dry season? When the temporary ponds dry up in hotter weather, most Pacific Treefrogs seek wet habitats on land, including tall grass and dark alcoves in the ground.
  6. What other places nearby are Pacific Treefrogs common? Other preserves where Pacific Treefrogs are common include Windy Hill Preserve, Skyline Ridge Preserve, and Mori Point Wetlands in Pacifica. These areas contain larger, more permanent bodies of water with adequate plants where these frogs can be found most of the year.
  7. Where can I learn more? California Herps.

Information compiled by Matthew James 2013