Monday, February 2, 2015


Red-bellied newts spend most of their lives underground and we know little about what they do there.   
The genetic results for the unusual population of red-bellied newts were in. Two newts from the newly discovered population in Santa Clara County were compared to forty newts from the main range in Sonoma, Mendocino, and Humboldt Counties. The populations were genetically indistinguishable from each other.

They were all the same. We were stunned.

This meant we could not determine if the previously unknown Stevens Creek newts were a naturally disjunct population or were introduced by humans from the northern range. These were surprising results for a salamander species.
The University of California - Berkeley team along with Midpen staff, volunteers, and neighbors spent years investigating this new population of red-bellied newts in the Stevens Creek watershed of Santa Clara County in the Santa Cruz Mountains of California  
The Berkeley team (Sean Reilly, Daniel Portik, Michelle Koo and David Wake) published the results in the Journal of Herpetology in September 2014: Discovery of a New, Disjunct Population of a Narrowly Distributed Salamander (Taricha rivularis) in California Presents Conservation Challenges. I have no expertise in genetics and won't go into the details of their analysis - these can be found in the published paper. A quick summary is that two mitochondrial genes and one nuclear exon were sequenced. The authors state:
Taricha rivularis lacks geographically structured mitochondrial lineages and exhibits extremely low levels of overall genetic diversity. The nuclear marker POMC is invariable, and less than 0.2% divergence in mtDNA is found across the approximate 200 km geographic range of the species, remarkably low for salamanders in this region, and for salamanders in general . . . Other salamander species with similar coastal distributions exhibit substantially greater levels of mtDNA variation or geographic structuring
These results were unexpected because most salamander species show quite a bit of genetic diversity. Sometimes this is obvious to the human eye, such as the differently colored Ensatina subspecies 'ringing' the Central Valley of California. Other times, it takes genetic studies to show how some salamander populations have slowly developed unique quirks in their genetic code often as a result of geographic barriers or behaviors that isolate them into subpopulations.

Salmon are an example of a philopatric species that returns to breed in the same stream in which they were born. As a result, distinct salmon runs occur on separate river systems representing unique genetic material in the same species. If generations of salamanders likewise return to the same stream to breed, over time, one would expect the animals of each stream system to become less genetically similar to subpopulations of the same species in a different stream.

A recent study of California giant salamander in the Santa Cruz Mountains shows this pattern. Briana Callahan (2010), a graduate student at Sonoma State University, found that California giant salamanders north of San Francisco Bay (in Marin, Sonoma and Mendocino Counties) are genetically divergent from populations in the Santa Cruz Mountains, probably as a result of the formation of an inland sea millions of years ago which isolated these distant populations from each other. Furthermore, she also found variation among the populations in the Santa Cruz Mountains often from one watershed to the next, indicating a finer scale of differentiation. Despite being the largest terrestrial salamander in the world, the California giants have a relatively low dispersal rate and an average home range of less than an acre. This may isolate subpopulations into separate breeding streams and therefore create genetic diversity among streams.

Returning to breed in the very same streams in which they were born - philopatry     
As Dr. Victor Twitty discovered, red-bellied newts are also philopatric, usually returning to within 50 yards of the stream in which they were born. And because red-bellid newts lay their eggs in very specific places - under rocks in fast-flowing streams - the tendency of subpopulations to develop would be even greater. Nevertheless, the Berkeley team was not finding any genetic divergence in red-belled newts over vast distances in the state.

Why were the red-bellied newts so similar to each other? An earlier study (Kuchta and Tan, 2006) found low levels of genetic variation in red-bellied newts in contrast to the other three Taricha species and suggested that either the red-bellied newts had recently expanded from a common point or their ability to travel relatively long distances for a salamander might allow continued exchange of genetic material.

Some of the Berkeley team's genetic results also indicate a geologically recent and rapid "population expansion [of red-bellied newts] following a bottleneck". It is unclear why they responded differently than the other Taricha and other salamander species of the central coast which over geologic time spread and contracted their ranges, became isolated in the peninsula of the Santa Cruz Mountains, and subsequently developed some degree of genetic diversity.

Just how far can this handsome newt travel - over generations?   
But let's go back to the last ice age about 20,000 years ago when sea level was intermittently lower, the coast of California was 15 to 20 miles farther west than the current shoreline, and there was a type of land bridge between the coastal land masses north and south of future San Francisco Bay. The California River (=ancient version of Sacramento River and Golden Gate Strait) drained inland territories to the ocean and was perhaps a broad freshwater valley. Could the red-bellied newt, which in Dr. Twitty's experiments at Pepperwood Creek moved more than five miles overland in a few years, have waited to expand to the south during this ice age instead of millions of years earlier when the giant salamander populations were more widespread? According to the Berkeley team, a "short time frame of approximatley 20,000 years could be insufficient for accumulation of fixed mutations in the isolated population". In terms of evolution, 20,000 years ago is not that long and even though the geology of California has changed quite a bit in that time, the red-bellied newts, capable of traveling long and rugged terrain, may have arrived in the Santa Cruz Mountains in nearly identical condition to their northern sisters.

Wild speculation and geologic dreaming? So inspires the dark-eyed stranger.

Warning belly: bright red warns predators of potent neurotoxin in this newt.  
Not likely to be used as fish bait.   
Even though recent human introduction of this population seems more likely, salamanders don't easily take to such long distant relocations. Of the few known successful introductions, two were a result of fishermen moving salamanders as bait, and one was accidentally introduced in a shipment of oak trees with bark (Bonett, 2007). Red-bellied newts do not make good bait due to the neurotoxin in their skin, and the poisonous effect of such "water-dogs" is generally well known by rural California residents and sportsmen.

Some of the beautiful and biologically rich park land protected in
Monte Bello Open Space Preserve and Upper Stevens Creek Park   
New genetic sequencing techniques could allow deeper analysis of the red-bellied newt populations in the future and perhaps solve the mystery as to whether the Stevens Creek newts are a cryptic natural population or introduced by humans. What to do in the meantime, until the next graduate student arrives with the tools and inclination to reexamine the frozen genetic material stored in the Museum of Vertebrate Zoology? In their paper, the Berkeley team recommends that the Stevens Creek population be protected as a hedge against threats to the patchy northern population where logging, and conversion into vineyards and housing are eliminating their unique breeding habitat.

A ten-thousand newt day - California newts breeding in pond on Monte Bello Open Space Preserve    
Much of the Stevens Creek watershed is protected in Monte Bello Open Space Preserve or Upper Stevens Creek Park, respectivley managed by the Midpeninsula Regional Open Space District and Santa Clara County. Sometimes, when a species is introduced by humans, the land managers attempt to remove it from natural park lands in order to protect the native species. An example is control of the American bullfrog introduced from the Eastern US which has invaded many of the same aquatic habitats preferred by the native San Francisco gartersnake.  Bullfrogs eat the adults, larvae and eggs all life stages of this endangered snake endemic to the Santa Cruz Mountains. Actually, bullfrogs eat everything including treefrogs and California red-legged frogs (another rare species), the preferred prey species of the San Francisco gartersnake which makes it even harder for them to survive.

Although we never saw their eggs, we often found small rough-skinned newts like this one indicating that they were likewise successfully breeding   
If the red-bellied newt was determined to be introduced to the Stevens Creek watershed, should it be removed? There are no plans to do so and this population does not appear to be in conflict with other animals or plants of the Santa Cruz Mountains. Most of the amphibian species which occupy the forests and streams of Stevens Creek are the same species that are found in the red-bellied's northern range. Indeed, both the rough-skinned and the California Taricha newts are sympatric with the red-bellied newt and sometimes all three species occur together in the northern range as they do in the Stevens Creek watershed. It is obvious they have separate breeding strategies, and likewise they probably have different feeding niches at least for much of the year when the red-bellieds are far underground, so it is unlikely that they compete with each other to any significant degree.

Random Truth was one of several nature bloggers who helped us search for red-bellied newts on rugged terrain.  He shares his take on the adventure with fabulous rbn photos and humor at Nature of a Man.    
As it turns out, the Midpeninsula Regional Open Space District has protected a key property in the Stevens Creek watershed that appears to support the main population of red-bellied newts. In February 2014, I suddenly had the opportunity to be the first to check a small tributary on that property. Who should I invite to join me? It had to be Chuck-the-Runner who in 2009 was the first to report red-bellied newts in the Stevens Creek watershed and had endured eight months of disbelief until his sighting was independently confirmed.

Chuck has an uncanny ability to find reptiles and amphibians.
The prior week, I had been surveying upland areas of the Stevens Creek watershed with a hardy group of fellow nature bloggers and we had seen 49 red-bellied newts traveling through forested slopes after a recent rain. The timing felt right to search the nearby property and we were even fortunate enough to run into the prior landowner as she was retrieving family heirlooms from an old barn. I flashed a photo of the California newt and the red-bellied newt side-by-side and asked if she had seen them on the property in her decades visiting there. "Yes, I've seen them, but that one is redder," she said as she pointed to the red-bellied newt in the photo.

"That one is redder," she said of my faded and splattered photo.
I looked at the pithy rancher in surprise. She was right about the real color of red-bellied newts. The photo I had with me was faded and smeared from many wet trips into the field. "Did you ever take photos of this newt when you were here, maybe photos that have dates on them?" I asked.

"Honey," she replied, "when I was a girl wandering these hills, I had a pony and a gun, nothing fancy like a camera." But she gestured in a general direction where she most often saw the "really red ones" and that was the same direction as the small creek on my map.

Monte Bello Open Space Preserve protects a diverse range of habitats for all kinds of newts   
To get to the creek, Chuck and I first had to pass a large pond in an open sunny meadow. In my previous quick trips to the property in that drought year, the pond had been dry and I had found the sad and shriveled carcasses of newts in its cracked bottom. But this day, after recent rains, the pond had started to fill up and we were delighted to see dozens and dozens of California newts and rough-skinned newts swimming and breeding in its clear, shallow depths. Some newts were gorging on treefrog eggs who also must have just arrived at the newly revived pond. We were hoping it was a newt-type of day.

We entered the forest and made our way downhill where we eventually found a small creek with a rushing flow no more than a foot or two deep and a few feet wide. The banks were winding and sharply cut with a wild tangle of downed trees and exposed roots. This was not going to be a gentle stroll besides a pastoral stream. The only way we could inspect that creek was to walk in it, and climb over, under or around ferns, branches, and trunks, hop over big rocks and sink into pools. We stepped into the cool water. I went upstream while Chuck searched downstream. We were seeing California newts lurking in the dark edges of the creek or sunning in open water. We had to closely examine these first newts just to make sure we weren't missing the red-bellieds, and soon our sleeves were soaked.

A small creek with lots of life and trip hazards   
A few hundred feet upstream, I spotted a red-bellied newt on the side of the creek, a juvenile with black toe tips. Chuck came charging up the creek at my call, and we did the ceremonial documentation of the first red-bellied newt of this new creek, 11:59 am, 12 cm long, with copious photos in case we didn't see another one for the rest of the day.

Red-bellied newt at creek edge - still has rough and bumpy skin   
Soon, the creek got too narrow and overgrown for us to see the bottom, so we turned to go in the downstream direction. To the sound of a pileated woodpecker, we found another small red-bellied newt on the creek bank, and then a rough-skinned newt swimming around a root wad. As we were ducking underneath a rusty strand of barbwire, we saw two adult red-bellied newts in the creek and the first stand of alder trees. The creek was changing in character, getting a little wider and deeper and side channels were contributing their flow and piles of large rocks which blocked our passage so we were frequently in and out of the water. And we were seeing lots of larvae of California giants joining the salamander party in the creek.

Most of the newts in the creek that day were males.
We handle newts briefly for identification purposes and then replace them at the same location and rinse our hands  
We were now up to a dozen red-bellied newts, then two dozen, and most of those we spied on the banks. Of those we found in the creek, only a few were swollen and slick from a multi-day residence in the water. Most still had bumpy and tough skin and look like new arrivals. The ones on the bank were often sitting erect on a high point like Rin Tin Tin peering over the top of a rock or root at the creek below.

Checking out the creek   
Four hours later, having seen 34 red-bellied newts alongside or in the small creek and filling six pages of newt observations in my field notebook, we finally reached the confluence with the main stem of Stevens Creek. I was soaked and shivering from the slow progress we made down the tangled creek, and shaking with exhaustion. We found no red-bellied newts in Stevens Creek or on the return trail, but Chuck and I were thrilled to have explored this aquatic epicenter of red-bellied newts. Somehow, we had timed our survey just right to find the newts as they were arriving at the creek edge.

Arboreal salamander at Newtlandia
In the following months, we returned to the property several times and found red-bellied newt eggs in the creek and adjacent tributaries. As we explored more of the property, I was delighted to frequently find other salamanders in its mix of grassland, oak woodland and forested habitats - adding slender salamanders, ensatinas, and arboreal salamanders to the previously seen California giant salamanders and 3 species of Taricha newts. On one sunny spring day, the pond was throbbing with thousands of California newts in amplexus and we enjoyed spectacular views of the rounded shoulders of Monte Bello Ridge on the east side of the San Andreas Fault, as we made our way to the unnamed rivularis-laden blue line in the dark forest, imperceptibly traveling northward on the west side of the fault. That was the day I ordained the property "Newtlandia".

I would like to have talked to Dr. Twitty about the discovery of red-bellied newts in the Stevens Creek watershed. I can't quite get my head around the fact that he would have been 108 years old when Chuck first reported the bright red newts on his running path. Even though Twitty has left us many scientific publications and a delightful reflection on his career in Of Scientists and Salamanders, I still would like to have shared the thrill of this discovery so close to his Stanford home and hear his interpretation of where the tumbling newts had come from and where they were going.

I would especially like to have told him about the small unnamed creek Chuck and I explored, spring-fed so that it was still flowing in a third year of drought, about our day of bouncing from creek bank to creek bank to get around big boulders, bowing under or climbing over log jams and constantly splashing and tripping in the cool, fast-moving current. I would report to him the size and sex and show him the photos of everyone of those 39 newts, how I wrote everything down in my field notebook and somehow managed to not drop my camera in the water. Well, almost everyone of those newts.

This is the part of the day I would most like to have shared with Dr. Twitty because even though he may have never said so in his papers, I know that he too was just as much in love with a world that could create such a marvelous creature. As I was twisting my body between fallen branches on the creek that day, I saw the chocolate brown head of a red-bellied newt pop up from an eroded scarp on the opposite bank. The newt set both of its fore limbs on the top of a curled alder root and turned its head to follow the downstream flow of the creek below. I reached across the small creek to pick up the newt with the intention of measuring it, but my feet were stuck between some roots and I couldn't quite stretch my arm that far without falling over. The newt shifted and looked up at me with its solemn dark eyes, slowly turned and with a flash of its bright red palms disappeared into the black passage behind the root.

Crawling in and out of holes in the ground, tree trunks and roots,  
red-bellied newts spend lots of time hidden underground   
At this point, Dr. Twitty would probably interrupt and remind me that of all the different types of salamanders in California, red-bellied newts spend most of their lives underground. They only come above-ground each year or every few years for that brief period when they breed in the streams. Indeed, from the end of their first summer when they shed their larval form, grow legs and crawl out of their natal stream, they go underground and disappear for five years. We have no idea what their lives are like underground and that is another mystery to us.

Even though 40 years have separated our stream-tromping, in many ways, Dr. Twitty and I have shared our adventures with this dark-eyed stranger. On rainy days I'm still out there with my gang, looking for red-bellied newts, searching for their eggs by sticking our hands in dark shadows under cool, flowing water, and recording it all in my field notebook. Except these days, if you look in my field notebook, you will find that we have christened that unnamed tributary. We call it Twitty Creek.

Exploring Twitty Creek
There are very few moments we have like that in our lives - a unique adventure, a new discovery,
something beautiful and improbable that exists on its own and has nothing to do with us.
We are just observers. - First Ever Red-Bellied Newt
This post is the last in a series on the discovery of red-bellied newts in the Santa Cruz Mountains of California. To start at the beginning of the series go to Mystery of the Red-Bellied Newt.

American bullfrog, Lithobates catesbeianus 
Sierran treefrog, Pseudacris sierra
California red-legged frog, Rana draytonii
San Francisco gartersnake, Thamnophis sirtalis tetrataenia
Arboreal salamander, Aneides lugubris
Yellow-eyed ensatina, Ensatina eschscholtzii xanthoptica
California slender salamander, Batrachoseps attenuatus
California giant salamander, Dicamptodon ensatus
Rough-skinned newt, Taricha granulosa
California newt, Taricha torosa
Red-bellied newt, Taricha rivularis

See also:

Bonett, Ronald M., Kenneth H. Kozak, David R. Vieites, Alison Bare, Jessica A. Wooten, and Stanley E. Trauth, September 2007, The Importance of Comparitive Phylogeography in Diagnosing Introduced Species: A Lesson from the Seal Salamander (Desmognathus monticola), BMC Ecology, 7:7.

Callahan, Briana, 2010, Impacts of Landscape Features on the Genetic Structure of the California Giant Salamander (Dicamptodon ensatus), Sonoma State University.

Howard, Arthur D., Geologic History of Middle California, University of California Press, 1979.

Kuchta, Shawn R. and An-Ming Tan, 2006, Limited Genetic Variation Across the Range of the Red-Bellied Newt, Taricha rivularis, Journal of Herpetology, Vol. 40, No. 4, pp. 561-565.

Reilly, Shawn B., Daniel M. Portik, Michelle S. Koo and David B.Wake, September 2014, Discovery of a New, Disjunct Population of a Narrowly Distributed Salamander (Taricha rivularis) in California Presents Conservation Challenges, Journal of Herpetology, Vol.48, No. 3, pp. 371-379.

Twitty, Victor Chandler, 1966, Stanford University, Of Scientists and Salamanders, W.H. Freeman and Co., San Francisco.


  1. Thanks for taking us all on this roller coaster of a journey, Cindy. It's been a thoroughly enjoyable read, with more absorbing science, excellent entertainment and plot-twisting suspense than anything on television. You have a gift and use it well.

  2. Thanks I&T: it really was an up and down affair for four years, so I am glad I was able to share that experience with you.

  3. Wonderful series! I agree with I&T: it was a most excellent blend of science, mystery, good people, and beautiful California, and it doesn't get much better than that, if you ask me. Thanks for these posts!

  4. J reminded me that San Francisco gartersnakes are live-bearing so corrections made above. Bullfrogs eat little and big gartersnakes and they eat the eggs, tadpoles and adult forms of the treefrogs and red-legged frog. Thanks for your off-line comment J. I love those type of comments!

  5. Replies
    1. Hmmm, dreaming about out next adventure whatever that might be. And if it is one that becomes a story, now I have more practice writing about it.

  6. Fantastic story. It is like a mystery novel! Thanks so much for sharing this, Cindy.


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