Red-bellied Newt Larvae only about an inch in length swim and crawl around in an aquarium.
Red-bellied Newt Larvae only about an inch in length crawl around on the bottom of a rocky creek in Mendocino County in late August.
Michael Braden made this video which he put on YouTube. It shows an interesting phenomenon involving an aggregation of Red-bellied Newts in and around an oak tree in Mendocino County.
Adults are 2 3/4 - 3 1/2 inches long (7 - 8.9 cm) from snout to vent, and 5 1/2 - 7 1/2 inches (14 - 19.5 cm) in total length.
A stocky, medium-sized, salamander with grainy skin, no costal grooves, and dark eyes.
(Other Taricha species have yellow in the eye.)
Breathes through lungs.
Larvae have numerous, fine black spots along the sides and back. The dorsal fin and balancers are not well-developed, compared to other Taricha species, but the hind limb development is more advanced at hatching.
Color and Pattern
Brownish black above, tomato red below.
There is dark coloring on the undersides of the limbs and a dark band across the vent.
Male / Female Differences
Breeding males develop smooth skin that looks wrinkled and baggy underwater, a flattened tail to aid with swimming, a swollen vent, and rough nuptial pads on the undersides of the feet to aid in holding onto females during amplexus.
Dark coloring across the vent is especially broad in males and often absent in females.
Rough-skinned when in the terrestrial phase.
Breathes through lungs.
Adults are terrestrial, becoming aquatic when breeding.
Adults emerge after a few fall rains and move around feeding for a period before migrating to the breeding stream. (Adults that are not breeding that year, continue to forage on the forest floor.)
Acitivity typically occurs at night and in the late afternoon, but newts are also found active in streams and on the surface in daylight during the breeding season and during rains.
Often seen moving in large numbers to breeding sites during breeding season.
Terrestrial animals spend the dry summer in moist habitats under woody debris, rocks, in animal burrows.
Juveniles apparently spend most of their time underground and are not active on the surface until near sexual maturity. Coexists with T. granulosa but unlike that species, T. rivularis breeds in flowing, not still, water.
Sometimes hybridizes with T. granulosa.
At one time, Red-bellied Newts were very abundant at some locations. One estimate from the early 1960's was that there were 58,000 - 60,000 breeding newts in a 1.5 mile (2.5 km) long stretch of Pepperwood Creek.
Longevity is estimated to be 20 - 30 years. (Amphibiaweb)
When threatened, this newt assumes a swaybacked defensive pose, closing its eyes, extending its limbs to the sides.
Unlike the other Taricha species, Red-bellied newts do not elevate or curl the tail. They sometimes lift the entire front of the body up off the ground, keeping the tail, pelvis, and hind limbs on the ground. This "unken reflex" exposes its bright red ventral surface coloring which is a warning to potential predators that the newt is poisonous.
Red-bellied Newts have poisonous skin secretions containing the powerful neurotoxin tetrodotoxin that repel most predators. The poison is widespread throughout the skin, muscles, and blood, and even the eggs. It can cause death in many animals, including humans, if eaten in sufficient quantity. (One study estimated that 25,000 mice could be killed from the skin of one Rough-skinned newt, the most toxic of the Taricha species.)
The poison can also be ingested through a mucous membrane or a cut in the skin, so care should always be taken when handling newts.
In most locations the Common Gartersnake, Thamnophis sirtalis, has a high resistance to tetrodotoxin which allows it to prey on Pacific Newts, genus Taricha. Thamnophis atratus and Thamnophis couchii have also been found with a strong resistance to tetrodotoxin that allows them to eat Pacific Newts.
Thamnophis elegans has also been found eating Taricha torosa in San Luis Obispo County.
An arms race between T. sirtalis and the tetrodoxin poison contained in Taricha has been documented, with newt toxicity varying by location and snake resistance to the toxin also varying by location.
(Edmund D. Brodie III. Patterns, Process, and the Parable of the Coffeepot Incident: Arms Races Between Newts and Snakes from Landscapes to Molecules. From In the Light of Evolution: Essays from the Laboratory and Field edited by Jonathan Losos (Roberts and Company Publishers). 2010.)
Diet and Feeding
Eats a variety of invertebrates. Larvae most likely eat anything they can fit in their mouth.
Reproduction is aquatic.
Breeding migration begins as early as late January, with adult males entering the water as early as early February.
Very heavy rainfall inhibits migration, as the newts need to wait until the streams recede from winter floods.
Mating takes place from late February to May, peaking in March, in clean rocky streams and rocky rivers with moderate to fast flow.
Adults will leave the water during heavy rains when the flow is high.
Ponds, lakes, and other standing waters are avoided.
Newts typically return to the same part of the same creek throughout their life.
Experiments have shown that they have an excellent homing ability to find their native stream segment using their sense of smell.
There is no evidence that they are territorial and defend their stream segment from others.
Males breed more frequently than females - usually every year or every 2 years, while females breed every 2 or more years.
Males arrive at the streams 1-3 weeks before females.
In the water, they transform into their aquatic phase, with loose skin, swolen cloacal lips, and an enlarged and flattened tail that aids them in swimming. They patrol the edges of the stream waiting for females to arrive. When they arrive, the females are sometimes mobbed by a group of males until one has grabbed onto her back in amplexus and cannot be wrestled off by the other males.
Males develop nuptial pads on the fingers and toes to help their grip during amplexus.
The male hangs on to the female in amplexus until she is ready to fertilize her eggs. At that time, the male deposits a spermatophore and the female picks it up with her cloaca.
The female lays and attaches a flattened egg mass usually only one egg layer thick under stones in the middle of the creek or rocks overhanging the creek, or onto submerged roots.
Clutch size is about 10 eggs.
Many egg masses are sometimes found under one stone.
Temperature determines how long the eggs take to hatch.
In a laboratory, eggs hatched faster at a higher temperature (16 - 20 days) than at a lower temperature (30 - 34 days.)
The larval stage lasts about 4 - 6 months.
In one population, the larvae hatched in late April, and transformed in late August.
Metamorphosis typically occurs in late summer and early fall.
Transformed juveniles leave the stream and go into hiding in underground shelters where they spend most of their life until they are old enough to breed (4 - 6 years.)
A stream or river dweller.
Found in coastal woodlands and redwood forest along the coast of northern California.
Larvae retreat into vegetation and under stones during the day.
Endemic to California.
Occurs along the coast from near Bodega, Sonoma county, to near Honeydew, Humboldt county, and inland to Lower lake and Kelsey Creek, Lake County.
The most limited in distribution of the three species of Taricha.
Disjunct Population in Santa Clara County
An isolated population occurs in the Stevens Creek watershed in Santa Clara County, California, more than 80 miles (130 km) south of the former known range of the species. The population was not found to be genetically divergent from the main population, which has the lowest genetic diversity of any coastal California salamander species, so researchers were unable to determine if the popuation is natural or introduced.
Sean B. Reilly, Daniel M. Portik, Michelle S. Koo, and David B. Wake (2014) Discovery of a New, Disjunct Population of a Narrowly Distributed Salamander (Taricha rivularis) in California Presents Conservation Challenges. Journal of Herpetology: September 2014, Vol. 48, No. 3, pp. 371-379.
Cindy Roessler has written a several-part blog post about the discovery and recognition of this dusjunct population of newts: Mystery of the Red-Bellied Newt.
Development of forests and grassland habitats for agriculture and housing may pose a serious threat by drying out the land and degrading streams, and creating more vehicular traffic with corresponding road mortality of terrestrial newts, especially during breeding migrations.
Stebbins, Robert C., and McGinnis, Samuel M. Field Guide to Amphibians and Reptiles of California: Revised Edition (California Natural History Guides) University of California Press, 2012.
Stebbins, Robert C. California Amphibians and Reptiles. The University of California Press, 1972.
Samuel M. McGinnis and Robert C. Stebbins. Peterson Field Guide to Western Reptiles & Amphibians. 4th Edition. Houghton Mifflin Harcourt Publishing Company, 2018.
Stebbins, Robert C. A Field Guide to Western Reptiles and Amphibians. 3rd Edition. Houghton Mifflin Company, 2003.
Behler, John L., and F. Wayne King. The Audubon Society Field Guide to North American Reptiles and Amphibians. Alfred A. Knopf, 1992.
Powell, Robert., Joseph T. Collins, and Errol D. Hooper Jr. A Key to Amphibians and Reptiles of the Continental United States and Canada. The University Press of Kansas, 1998.
Bartlett, R. D. & Patricia P. Bartlett. Guide and Reference to the Amphibians of Western North America (North of Mexico) and Hawaii. University Press of Florida, 2009.
Bishop, Sherman C. Handbook of Salamanders. Cornell University Press, 1943.
Lannoo, Michael (Editor). Amphibian Declines: The Conservation Status of United States Species. University of California Press, June 2005.
Petranka, James W. Salamanders of the United States and Canada. Smithsonian Institution, 1998.
Jones, Lawrence L. C. , William P. Leonard, Deanna H. Olson, editors. Amphibians of the Pacific Northwest. Seattle Audubon Society, 2005.
The following conservation status listings for this animal are taken from the November 2020 California "Special Animals List" and the November 2020 "State and Federally Listed Endangered and Threatened Animals of California" list, both of which are produced by multiple agencies and available here: https://www.wildlife.ca.gov/Data/CNDDB/Plants-and-Animals. You can check the link to see if there are more recent lists.
If no status is listed here, the animal is not included on either list. This most likely indicates that there are no serious conservation concerns for the animal. To find out more about an animal's status you can go to the NatureServe and IUCN websites to check their rankings.
Protected from take with a sport fishing license in 2013.
NatureServe Global Ranking
Uncommon but not rare; some cause for long-term concern due to declines or other factors.
NatureServe State Ranking
Imperiled in the state because of rarity due to very restricted range, very few populations (often 20 or fewer), steep declines, or other factors making it very vulnerable to extirpation from the state.