Pacific Tree Frog (Pseudacris regilla)

Order Anura, Family Hylidae (Tree Frogs), Genus Pseudacris, Species regilla. Note: Genetic studies have split this group into a species complex including P. sierra and P. hypochondriaca, but P. regilla remains the widely used umbrella common name.

Species

Family

Size

A small species with an adult Snout-to-Vent Length (SVL) of 2.5 to 5 cm (1 to 2 inches). Females are generally slightly larger than males. Metamorphs are tiny, often less than 1.5 cm when they leave the water.

Conservation

IUCN Status: Least Concern. Populations are generally stable and robust, though they face local threats from habitat loss, pesticide runoff, and the spread of the chytrid fungus (Batrachochytrium dendrobatidis).

Description

The Pacific Tree Frog is the 'voice of the West.' Small enough to sit on a thumb, this charismatic amphibian is a master of camouflage, capable of changing its hue from bright leaf-green to earthy brown in minutes to match its surroundings. Whether found in a remote mountain lake or a suburban backyard, its presence is usually signaled by its surprisingly loud, rhythmic chorus that can drown out all other night sounds.

Key Features

Dark mask/stripe through the eye, small round toe pads, and the ability to rapidly change color from green to brown. The presence of a dark mark between the eyes is also a strong indicator.

Physical Description

A small, slender frog with a rounded snout and a relatively large head. It features prominent, large eyes with horizontal pupils and a clearly visible tympanum. The limbs are long and thin, ending in well-developed toe pads (disks) that enable climbing, despite spending much time on the ground.

Skin Texture & Coloration

Skin is generally smooth but can appear slightly granular. Coloration is highly variable, ranging from shades of green to tan, brown, or gray. This individual shows a bright green dorsal surface with mossy or lichen-like tan markings on the limbs. A dark, distinct 'eye mask' stripe runs from the nostril through the eye to the shoulder.

Distinguishing Features

The most diagnostic feature is the dark brown or black mask (eye stripe) extending from the nose across the eye to the shoulder. Additionally, they often have a Y-shaped or triangular dark mark on the top of the head between the eyes, and small adhesive toe pads.

Habitat

Extremely versatile; found in forests, meadows, pastures, and urban gardens. They prefer areas near quiet water like ponds, seasonal pools, or slow streams for breeding. They can be found from sea level up to high alpine meadows above 10,000 feet.

Geographic Range

Common throughout the Pacific coast of North America, from British Columbia (Canada) south through Washington, Oregon, and California into Baja California (Mexico), extending east into Montana and Nevada.

Behavior

Primarily nocturnal but often active during the day during the breeding season. They are excellent climbers but frequently forage in low vegetation or on the ground. When threatened, they rely on crypsis or jump into water to hide in the silt.

Diet & Feeding

Insectivorous. Adults consume a wide variety of small invertebrates including beetles, flies, spiders, ants, and leafhoppers. They are sit-and-wait predators that use a sticky, projectile tongue to catch moving prey.

Reproduction

Breeding occurs from winter to early summer depending on latitude. Males migrate to water and form loud choruses. Amplexus is axillary. Females lay small clusters of 10-70 eggs attached to underwater vegetation. Total clutch size can exceed 500 eggs.

Vocalizations

The classic 'ribbit' or 'creee-eeek' sound. It is a two-part loud, high-pitched croak. This call is so iconic that it was recorded for early Hollywood films and has become the universal 'movie frog' sound, even in films set in regions where the frog does not live.

Life Cycle

Eggs hatch in 1-3 weeks. Tadpoles are dark brown with gold flecking and develop for 2-3 months before undergoing metamorphosis. Sexual maturity is typically reached within one year, with a wild lifespan usually limited to 2-5 years.

Conservation Status

Toxicity & Defense

While not toxic to humans, they produce mild skin secretions that can be irritating to mucous membranes. Their primary defense is camouflage (crypsis) and their remarkable jumping ability to escape predators.

Ecological Role

They are a vital link in the food chain, serving as a major predator of mosquitoes and other insects, while providing a primary food source for birds, snakes, and larger amphibians.

Similar Species

Boreal Chorus Frog (Pseudacris maculata) lacks the distinct large toe pads and has more striped dorsal patterns. The California Red-legged Frog is much larger and lacks the distinctive eye mask.

Observation Tips

Listen for their loud choruses near shallow, still water on spring nights. Use a flashlight to spot the reflecting eyes. They are often found hiding in the folds of large-leafed plants like hostas or calla lilies during the day.

Handling & Safety

Handle only with wet hands to protect their permeable skin from oils and salts. Wash hands thoroughly afterward to avoid irritation from skin secretions. Minimal handling is always best for the frog’s health.

Seasonal Activity

Active year-round in milder coastal climates. In colder regions, they hibernate in leaf litter or underground burrows during the winter and emerge with the first heavy rains of spring.

Cultural Significance

Famed as the 'Hollywood Frog' because its call is used in virtually all movies for night-time background noise, regardless of the film's geographic setting.

Interesting Facts

Despite being called a 'tree frog,' they are actually more terrestrial and are frequently found on the ground or in low shrubs. They are the official State Amphibian of Washington.

Identified on 7/20/2026