Taricha rivularis (Twitty, 1935)

Taxonomy and Naming

Taricha rivularis, commonly called the red-bellied newt, was first described by Twitty in 1935.

Adult Size

When fully grown, this species measures 2.75 to 3.5 inches (70 to 89 mm) from snout to vent, and 5.5 to 7.5 inches (140 to 190 mm) from snout to the end of the tail.

Skin and Coloration

It has grainy skin, with a brownish-black dorsal side and a bright tomato-red underbelly.

Sexual Dimorphism

Males often have a broad dark color patch across the vent that females lack.

Breeding Male Morphology

Breeding males develop smooth skin and a flattened tail.

Species Distinguishing Features

This newt can be told apart from other coastal newts by its red belly and the absence of yellow in its eyes.

Native Range

The red-bellied newt is native to coastal California.

Main Distribution

Its main range extends along the coast from Bodega in Sonoma County, inland to Lower Lake, and north to Honeydew in Humboldt County.

Primary Habitat

It inhabits coastal woodlands, particularly redwood forests.

Disjunct Population

A separate disjunct population exists 130 kilometres (81 mi) south of Sonoma County in the upper Stevens Creek watershed in the Santa Cruz Mountains, and this population is genetically identical to the main Sonoma County population.

Larval Form

Red-bellied newts start life as aquatic larvae, which resemble tadpoles but are more elongated and have external gills.

Juvenile Development

After larvae mature into adult form, a process that takes around four to six months, they leave the water to live underground until they reach breeding age, which typically takes four to six years.

Adult Lifespan

Adults can live between 20 and 30 years.

Breeding Aggregation Timing

Once sexually mature, males begin gathering at stream banks as early as January or February.

Mating Period

Females join the aggregation one to three weeks later to mate.

Oviposition Habitat

Red-bellied newts lay their eggs in fast-flowing streams or rocky rivers.

Egg Clutch Characteristics

Females deposit eggs in roughly 12 streamlined clusters, each holding six to 16 eggs.

Egg Placement

Eggs are most often attached to the undersides of rocks, or to branches and roots that extend into the water.

Post-Breeding Movement

After breeding, adults leave the stream moving at an angle upstream rather than directly uphill.

Breeding Frequency

Unlike males, females do not breed every year.