Monday, January 26, 2015

A Newt Egg Crawl

Monte Bello Open Space Preserve is split by Stevens Creek and the San Andreas Fault  
 I had a third theory about how red-bellied newts arrived in the Stevens Creek watershed. We doubted the lost race theory because surely some of the thousands of people who live in, visit or study the Santa Cruz Mountains every year would have previously discovered them. And likewise, a recent, successful introduction by humans seems questionable because their strong homing instinct would send the newts plodding across roads and over cliff edges to their death, difficult conditions to get a breeding population established at a new location. Instead, maybe there was a "wormhole" - a passage through space and time that delivered red-bellied newts to this remote corner of Santa Clara County without swimming the deadly saline waters of San Francisco Bay.

Excuse me for mixing up astrophysics and geology. California has spectacular geology that sometimes seems as if it is from science fiction. Perhaps, across the epochs, there was an unusual geologic event equivalent to a wormhole that explains how red-bellied newts arrived and thrived in the Stevens Creek watershed.

After all, the Santa Cruz Mountains were formed at the edge of the continent, and if you look closely at maps or as you wander around, the Stevens Creek watershed has some unusual landforms. The upper reaches of the creek follow the trace of the San Andreas Fault (or its precursors), one of the world's longest and most active faults. Then five miles downstream from its headwaters, the creek takes a sudden sharp turn to the east, is dammed at Stevens Creek Reservoir, and then makes a final twelve-mile run through cities to discharge into San Francisco Bay. Technically known as an offset drainage, doglegged Stevens Creek is one of those obvious surface clues that we are in the land of earthquakes (Stoffer, 2005).

An examination of the mountainous shoulders of Monte Bello Open Space Preserve provides other clues. The long northwest-southeast layout of the preserve is divided in two by Stevens Creek, and therefore the San Andreas Fault Zone, and this means the geologic backbone of the ridges on each side are different and so is their vegetative cover.

Fog rises over Stevens Canyon with the open grassy and lightly wooded hillsides of the North American Plate in the foreground and the forested ridge of the Pacific Plate in the right background.   
The slopes to the east of the creek are on the North American Tectonic Plate with Franciscan Complex volcanic rocks covered by sedimentary rocks from an interior sea and from the former encroachment of a higher ocean on the west (Graymer et al, 2006). The golden eastern hilltops of Monte Bello Ridge are covered by grasslands and chaparral. A hike down Canyon Trail in the Monte Bello Open Space Preserve is on the North American Plate and passes by multiple springs and sag ponds, both signs of fault-formed geology.

The slopes to the west of the creek are on the Pacific Tectonic Plate moving slowly to the northwest. Their granitic bedrock is overlain by marine sedimentary rocks (younger than the sedimentary rocks on the North American Plate) and is covered by dense forests of Douglas firs in the canyons and by mixed oaks, bays and madrones towards the ridge top. A drive down the forested roadsides of Skyline Boulevard (Highway 35) in the Santa Cruz Mountains is on the Pacific Plate.

 Searching the Stevens Creek watershed for red-bellied newts
with help from Random Truth of Nature of a Man and Katie of Nature ID    
When we reviewed Stebbins' description of red-bellied habitat in northern California as "mixed conifer and broadleaved woodland broken by patches of grassland", it sounded like either side of Stevens Canyon would be suitable as long as there was seasonal water (Stebbins and McGinnis, 2012). And Dr. Victor Twitty described Pepperwood Creek in Sonoma County, where he conducted many years of red-bellied newt studies, as a small stream easily waded that winds through forests and an open meadow with a ranch road on one side (Twitty, 1966). Aerial photographs show open grassy hills to the north of Pepperwood Creek and a steep heavily wooded slope to the south. Twitty observed most of the newts emerge from the wooded slope in the spring and travel to the creek for breeding. Again, the mixed vegetation types at Twitty's Pepperwood Creek seemed to somewhat match the upper reaches of Stevens Creek.

A red-bellied newt climbs over a Douglas fir cone on the west side of the San Andreas Fault.      
As our surveys piled up, we noticed that we rarely saw red-bellied newts on the eastern side of the San Andreas Fault. No matter how they originally arrived, we were seeing red-bellied newts of all sizes, so we suspected this was a well-established breeding population, but we needed to find eggs to prove it.

In May 2010, the Berkeley graduate students returned to search for signs of reproduction of the red-bellied newts in the Stevens Creek watershed. On this hike, Sean Reilly, Daniel Portik and I tumbled up and down slopes in the general direction of the closest water just as the park team had seen the newts travel in our ten forays of the the past five months. When we reached a tributary, we walked up the channel doing the 'egg crawl'.

California newts laying large egg masses in a pond on Monte Bello Open Space Preserve for all to see.   
As their species name rivularis implies, red-bellied newts prefer the fast-moving sections of streams to breed. I was familiar with finding California newts boldly breeding in ponds or quiet pools and edges of streams, and their large, easy-to-spot egg clusters attached to vegetation, sunken branches or even piled on the pond bottom. One can watch the entire cycle of mating, egg laying, egg development and hatching of California newts over a period of a few weeks from the dry shore of a pond in a sunny meadow.

Doing the newt egg crawl on a flat section of Stevens Creek.
Photo by Katie of Nature ID.   
Searching for red-bellied newt eggs was not so easy. This new challenge required slowly walking up the central flow of a stream and reaching under any large rocks or drowned logs to feel for soft egg masses. We were palpating the unseen dark reaches of underwater objects for what Stebbins (2003) describes as "flattened, firm clusters of 5-16 (10) eggs. Clusters about 1 in. (2.5 cm) in greatest diameter, often only 1 egg thick and usually attached to undersides of stones in streams." And by stones, he probably meant big well-anchored ones since it made no sense to lay eggs on an object that would roll in the flashy spring flows and expose the eggs to drying air or predators.

California giant salamander in its neotenic form with feet, an aquatic tail, and big jaws.   
It was creepy sticking my hands under rocks with delicate fingertips seeking what Sean further described as small, flat jelly doughnuts. Who knew what else lived under the dark rocks. I kept reminding myself that I was no longer working in Florida and there are no venomous snakes that live in California streams. The whole time we were walking up the small tributaries, dark gray shadows were skating past our ankles or darting out from underneath cut banks or the submerged rocks we were checking. Patrick said they were the larvae of California giant salamanders. He splashed after them until he caught several and flipped them onto the stream bank for me to see. Bullheaded, they gripped the brown leaves on the bank with their four legs for a few seconds staring us down before they whipped their slippery tails and plopped back into the stream. I wondered how any eggs or larvae in the creek would survive those giant jaws.

Doing the newt egg crawl on a small creek in the Stevens Creek watershed.   
The small creeks were charming, no wider or deeper than two or three feet with clumps of rushes contouring their banks and sunlight filtering through the high canopy of deciduous maples and evergreen bays. Walking, slipping, and fondling all likely surfaces in the creek, water was seeping into our boots and under our rain gear. As I prowled among the riffles and pools, I imagined what it would be like to be a salamander living in this wet world of bright sun and dark hollows. The creeks were so small, I suspected they might dry up in California's annual summer drought before any newt larvae could mature into their terrestrial form. On the other hand, some sections had well-established perennial instream and wetland vegetation suggesting that a spring flow may feed them year round. Yet we felt no jelly doughnuts under their rocks, occasional single small spots of gelatinous matter (perhaps eggs of the rough-skinned newt), but nothing that felt like a red-bellied newt cluster.

After a few hours, I spied a white ridge top above us and recognized it as an erosion scar visible from the opposite side of Stevens Creek. I suggested we head that direction as a shortcut to the larger stream. Sean and Patrick agreed and as we trudged up what turned out to be a knife ridge, I grabbed at roots and rocks to keep from embarrassing myself in front of the nimble young men. I couldn't imagine newts traveling this route and we hadn't seen any in a long time so I wondered if I was leading the team on a wild goose chase. The opposite side of the ridge was even steeper but we made our way down to Stevens Creek, squeezed out our clothes and sat down for lunch in a sunny warm spot.

Under rocks next to the turbulent main flow - where the red-bellied newts laid their eggs.  
I was a little reluctant to get back into the water after lunch and was bouncing along the bank when within a few minutes of starting our next egg crawl Patrick announced, "Here's one." His long arm was half under a large partially submerged rock with churning foam splashing up to his armpit. Over the noisy chatter of the stream, we asked him to describe what he felt in that wet hole. "Jelly doughnut", he responded, "Here, you feel it." Sean got his arm under the rock and agreed. I splashed over and with my face nearly in the stream in order to get my shorter arm far enough under the rock, they both guided me with encouraging tips like "Feel for the big cavern in the back" and "try to get your fingers directly under where I'm pointing on top of the rock here." Suddenly, I felt it too, a small squishy flat clump cemented to the bottom of the rock with a hollow in the center about the same size as my fingertip.

It took the three of us to flip over the rock to visually confirm the egg cluster. It was 2 cm wide of a hazy color with nine lumpy bumps some of which had a white C-shape, the embryo. After quickly photodocumenting the distinct egg cluster, we carefully flipped the rock back over in the same orientation so as to not crush the eggs and make sure they were protected by the overhanging rocky ledge but still received oxygen-rich waterflow.

Mass of red-bellied newt eggs. The female newt must swim under the rock and anchor herself to its lower surface as she turns around in a circle to lay the eggs.    
Patrick looked around for a similar large rock surrounded by whitewater and found another egg cluster. We likewise photodocumented that one and carefully restored the rock to its proper stream orientation. "That's it", the graduate students declared, "you've got  red-bellied newts breeding in Santa Clara County. Now let's go find some food." On the way out the canyon, they described their favorite East Bay burger and taco joints and I told them about Alice's Restaurant, the closest hamburger and beer joint in the neighborhood. La Honda may not have all the cultural and culinary advantages of Berkeley, but it was good hot food after a wet and strenuous field survey. And we found several more adult red-bellied newts as we crawled our way out of the forest.

Montgomery Woods State Reserve near Ukiah, California.
Not a place I could find red-bellied newts.   
As the initial curiosity wore off, it was more difficult for me to slip out of the office on rainy days for another check of the Stevens Creek watershed. Finally, by spring of 2013, I schemed a visit to the red-bellieds in their main range.  First, I visited Montgomery Woods State Reserve in Mendocino County because it was near Ukiah where Dr.Twitty originally collected red-bellied newts in 1933. This redwood forest was flat and swamp-like, much different than the bands of redwood trees clustered along downcut streams that we have farther south. Shallow channels wound around the base of large redwood trees, and I saw a few giant salamanders, but no red-bellied newts.

Pepperwood Preserve in Sonoma County has a wide range of vegetation types,
undoubtably influenced by geology.
Next, I managed a special invitation to explore Pepperwood Preserve in Sonoma County. This Pepperwood Preserve, northeast of Santa Rosa, is a nature preserve dedicated to research and education, run by a public charitable organization and still affiliated with the California Academy of Sciences. It is not the same ranch where Dr. Twitty studied newts on Pepperwood Creek. The two locations are both in Sonoma County and both feature the California bay (aka pepperwood), but are about 50 miles apart.

A red-bellied newt patrolled this pool in a creek at Pepperwood Preserve.  
Red-bellied newt at Pepperwood Preserve
Interestingly, all three Taricha newts have been found on Pepperwood Preserve. Red-bellied newts have been recorded there in the months of November through April. It was a long and beautiful hike to where the preserve staff suggested I look for red-bellied newts, and a climb down into the stream bed. Once there, I found a small, rocky stream with a series of shallow pools between logjams. Some sections of the stream were already dry in that drought year. I observed 4 different red-bellied newts, each in its own pool usually with a small waterfall at its head. Giant salamanders were also in the pools indicating that the giant did not eat the neurotoxin-laden red-bellied. I did not see any California newts or rough-skinned newts on the preserve on that day. And I was able to find red-bellied newt eggs confirming it was a breeding stream. Although the creek in Pepperwood was primarily surrounded by redwood trees, the size, substrate and remoteness was similar to Stevens Creek. 

Red-bellied newt eggs at Pepperwood Preserve.   
And then I checked a geology map. Maacama Fault crosses the Pepperwood Preserve within one-half mile of where I observed these red-bellied newts.

Red-bellied newt patrolling a stream pool at Pepperwood Preserve.   
After our splashing adventure among the cracks and pressure ridges of the San Andreas Fault, the Berkeley team suddenly went silent. Understandably, a study of this small, odd population of red-bellied newts in Santa Clara County was not their main focus. The graduate students had demanding research trips to other countries to complete their degrees. Dr. Wake was busy with publications spreading the dreadful news about worldwide declines in amphibians. When I checked in with Dr. Wake, he described a bump in the genetic studies that would require another round of analysis. What could we do but wait, and walk, and come up with more bizarre theories until the genetic evidence solved the mystery in Stevens Creek.

Red-bellied newt patrolling the stream bottom at Stevens Creek.
How closely are these two newts related?   
To be continued as Newtlandia.
This post is the tenth 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.

California giant salamander, Dicamptodon ensatus
Rough-skinned newt, Taricha granulosa
California newt, Taricha torosa
Red-bellied newt, Taricha rivularis

See also:

Brabb, E.E., R.W. Graymer, and D.L. Jones, 1998, Geology of the Onshore Part of San Mateo County, California: A Digital Database, US Geological Survey, Digital Open File Report 98-137.

Graymer, R.W., B.C. Moring, G.J. Saucedo, C.M. Wentworth, E.E. Brabb, and K.L. Knudsen, 2006, Geologic Map of the San Francisco Bay Region, US Geological Survey

Stoffer, Philip W, 2005, Field Trip to the Skyline Ridge Area in the Central Santa Cruz Mountains, Chapter 7, and Introduction, Chapter 1,The San Andreas Fault in the San Francisco Bay Area, California: A Geology Fieldtrip Guidebook to Selected Stops on Public Lands, US Geological Survey, Open File Report 2005-1127, Online Version 1.0.

Stebbins, Robert C., 2003, A Field Guide to Western Reptiles and Amphibians.

Stebbins, Robert C., and Samuel M. McGinnis, 2012, Field Guide to the Amphibians and Reptiles of California, University of California Press.

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

1 comment:

  1. Thank you for a delightful series on the Red-bellied Newt. I'm a native of Cazadero, Sonoma County. RBNs are abundant here and since childhood they have been among my very favorite critters.

    I hope the final genetic results are in soon and explain the range anomaly.


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