Over the last couple of weeks I've visited the seasonal ponds in the East Bay at Sibley Volcanic Preserve and small creeks at Briones Regional Park and found California newts engaging in their spring rituals of courtship and mating. The long, dry winter and late, sporadic rains have likely made this less than a banner year for amphibians. Newts spend the Bay Area’s dry months of summer and fall “estivating,” holed up in underground burrows, gopher holes, or under logs and rocks, waiting for the rain.  Wet weather calls them to action. Leaving their upland burrows, newts migrate, one slow, tiny step at a time, braving roads and other dangers. They gather in their natal ponds and streams to mate and lay their eggs.

Multiple males and females mating in a cluster at Sibley

Their courtship rituals are ancient and complex. Drawn to the water, both males and females enter and begin the search for that special someone, or two, or many. Males undergo a physical transformation with their tails changing shape to allow for faster swimming and their front feet develop thickened, rough pads for grasping slippery females. When a male finds a willing female he grabs her from above. They glide around underwater together for hours or even days, surfacing to breathe and swimming through cattail and grassy forests. He rubs her forehead with his chin, waiting for her lift her head.  If she’s not interested, she keeps her head down. Some newts play the numbers game and come together in clusters with multiple males and females.

Male newt courting a female at Sibley

Mating success occurs when the male guides the female to the bottom of the pond where he deposits his sperm packet. It looks like a small, fantastic sculpture with the vital genetic material poised like an apostrophe at the top. She takes it into her body and holds it for some time before fertilizing eggs as she lays them.  She may mate with multiple males. The female finds underwater plant stems to lay her clusters of eggs upon, encasing them in a gelatinous mass. She may lay as many as 300 eggs in a mating season. The embryos develop underwater until they're ready to hatch. Once mating is completed, most adults head back to their upland feeding and hibernation areas, leaving the young to fend for themselves.

Newt egg mass on plant stem at Sibley pond

The perpetuation of the California newt species hangs in the balance with many hazards. A dry winter can create a host of problems. Egg masses can become exposed as the pond evaporates and the young may not make it. After hatching, young newts breathe water through their gills before they transform into air-breathing adults. If their ponds dry up too soon, they’re out of luck. Predators abound in the ponds, too. Garter snakes have a long history with newts and have developed immunity to their toxic skin. Some years the ponds are full of both garter snakes and newts.  Introduced animals like crayfish and mosquito fish, and a new "super hybrid" species of salamander eat young newts.  The adult's trek from their burrows to ponds and streams can be fatal with cars, bikes, and cattle claiming the lives of some of these tiny travelers. Even toxic skin can’t save them from being small, easy to overlook, and dependent on seasonal water.

Additional Links:

Briones Regional Park website

Sibley Regional Park website

Newt photos and illustrations

KQED QUEST Science Hike at Briones

Recent discoveries of a Lilliputian lizard and elfin amphibian, fascinating in their own right, highlight one of the most enduring questions in biology: what controls the evolution of body size? Why do some taxa grow smaller and smaller, while others grow larger and larger, as if they’d tumbled down the rabbit hole with Alice and devoured all the curious potions and cakes she found there?

The question endures in large part because body size affects nearly every aspect of an organism’s existence, from physiology (temperature regulation and metabolism) to ecology (life history and foraging strategies) and evolution (reproductive success over time).

For more than a century, biologists thought evolutionary taxa, or lineages, grew larger and larger over time, a phenomenon known as Cope’s Rule, illustrated most often by horse evolution. Modern equids, scientists believe, evolved from the diminutive Hyracotherium (commonly known as eohippus, or “dawn horse”), which appeared in the fossil record some 55 million years ago. Many textbooks mistakenly liken Hydracotherium to a fox terrier (think Asta of The Thin Man movies), but the ancestral horse was more Lassie than Asta, as Stephen Jay Gould famously explained in his essay "The Case of the Creeping Fox Terrier Clone."

A replica skeleton of Hydracotherium vasacciensis, the putative ancestral horse, at the Museum of Natural History in Washington, D.C. (Photo: Jeff Kubina)

In 1997, though, David Jablonski showed that (as usual) biology rarely follows hard and fast rules. In a 10-year review of fossils covering 16 million years and 1,000 species from 191 lineages of bivalves (clams and scallops) and gastropods (snails and slugs), Jablonski found that just as many taxa decreased in body size over time as increased. And even the horse example has come under fire. A 2004 study analyzed horse fossils in light of recently resolved relationships among evolutionary groups and showed that while the lineage that gave rise to the modern horse grew larger, others shrank.

Still, examples of lineages evolving toward larger body size abound, with evidence linking greater size to higher fitness (better survival and mating success for individuals). If you’re big (say, a lion or other large carnivore), it’s easier to catch prey, avoid predation (though elephants, like mammoths before them, may perish at the hands of human hunters), survive tough conditions, attract mates (silverback gorillas claim exclusive breeding rights to females), and claim more resources than your competitors.

Given the advantages of size, one might think the tiny frog and chameleon are simply freaks, outliers among a field of giants. But the fossil record offers plenty of examples of large animals shrinking over millennia (known as “phyletic dwarfism”), often after winding up on islands or other restricted ranges.

Until about 10,000 years ago, dwarf elephants inhabited Crete and other Mediterranean islands, which favored smaller, nimbler forms that could survive on less food and manage the rocky terrain. Even dwarf mammoths (the oxymoron notwithstanding), dinosaurs, and hominids (Homo floresiensis) once inhabited isolated islands.

If you’re small, you might reproduce quickly, offer too little reward for a predator’s effort, and maybe even prove too hard to see.

Paedophryne amauensis, a minute frog found in Papua New Guinea, may be the smallest vertebrate on Earth. (Photo: PLoS ONE. doi:10.1371/journal.pone.0029797)

That seems to be the case for a pint-sized amphibian found, through no small effort, in the forests of Papua New Guinea, which its discoverers claimed as the “world’s smallest vertebrate.” Because the largest vertebrate, the blue whale, and (previously) smallest, a fish, are aquatic species, some biologists thought a water-based lifestyle may facilitate the evolution of extreme size. But, as the scientists argue in the paper describing the frog, this doesn’t explain how extreme miniaturization evolved at least 11 times in terrestrial frogs.

The 7-8 millimeter frog, named Paedophryne amauensis, is active mostly at dawn and dusk, sounding more like a cricket than a frog when it calls out to potential mates from the leafy detritus of the forest floor. (The authors dubbed the species “amauensis” after the region near Amau Village where it was found.) Leaf litter in tropical forests stays moist throughout the year, keeping the minute amphibian safe from desiccation and likely explaining the evolution of its life history: offspring bypass the tadpole stage, emerging fully formed, though even tinier, avoiding fish, insects, and other aquatic predators. Of course, teeny adults would be at higher risk from predators if they lived in the water, too, which might explain why the species carved out a niche in upland areas with a lower diversity of such threats.

Brookesia micra, one of four dwarf leaf chameleon species found in Madagascar. (Photo: PLoS ONE. doi:10.1371/journal.pone.0031314)

And just last month, another group of researchers reported their discovery of four new species of dwarf chameleons, one so small it can balance on the tip of a match head. The mini chameleon, Brookesia micra, measures a smidgen over an inch from snout to tail, and seems restricted to Nosy Hara, a small (naturally) island off the coast of Madagascar. An extensive survey of Nosy Hara and adjacent islands in 2007 failed to spot the little lizard, which scampers around limestone rocks and dry forest leaf litter during the day and roosts on low-lying branches a few inches above the ground at night.

Unlike their amphibian counterparts, the minuscule reptiles inhabit relatively dry tropical areas. Because small body size carries a higher risk of desiccation from the proportionally higher body surface area, it’s surprising the lizards live in a dry environment, the scientists explain in their report. It’s possible they’ve adapted to certain features of the landscape that retain moisture, like leaf-filled fissures in limestone.

The tiny frog and chameleons may or may not win the title for smallest of their kind, but the distinction is beside the point. The discovery of these new species offers a rare ray of hope amid ongoing reports of devastating declines in amphibian and reptile populations around the world, mostly due to habitat destruction. These dwarf species have likely benefited from minimal space and resource requirements, and being too tiny to spot. And for me, it’s no small comfort to know that we can still find wonders, both beautiful and strange, on this side of the looking glass.

 National Wildlife Health Center Investigates Educator Guide

“The National Wildlife Health Center is sort of what it says. We're a national center and we receive carcasses from refuges and state management areas all around the country, usually from state biologists, federal biologists, tribal biologists,” says disease investigation chief Dr. Scott Wright. Those carcasses shipped overnight to the center are most often samples taken from large animal die-offs. It’s the job of the center to determine the cause of death.

“Much like the CDC would do for human health, or the USDA would do for agricultural animals, for livestock and so forth, that's the role we play for wildlife,” says Wright.

At the heart of the center is a level 3 bio-safety lab where the animal samples are processed and examined through necropsy, the animal version of an autopsy. “Every case that comes in is a potential real challenge,” says veterinary pathologist Dr. David Green. “I sit down and look at all of these different lab results; the toxicology, the poison tests, the virus cultures, the bacterial cultures. And I have to put all of these pieces of information together to determine why was that animal sick, why did that animal die or why did 500 birds die at this site.”

It was 5000 red winged blackbirds dying in a small Arkansas town on New Year’s Eve 2010 that briefly thrust the work of the Center into the national spotlight. “Oh there were just all sorts of clever names applied to the event,” remembers Green. “'Aflockolypse' was, I think, the cleverest.”

Harbinger of the end times, covert military testing, magnetic disruption, all manner of strange theories were applied to the event. The intense interest surprised the NWHC staff, says Wright. “There were people calling me at my home at night, on weekends wanting to know what was going on.”

The cause of death, determined after numerous bird necropsies, was much more banal than the theories. “All of the tests and cultures that we did for infectious diseases and parasites and chemicals came back negative,” says Green. “Basically it came down to, we couldn't find anything other than physical injuries, what we call blunt force trauma in the birds.”

Those necropsy findings, combined with field reports of New Year’s fireworks, and the fact that blackbirds are terrible night flyers came together to paint a picture of startled birds flying into each other and stationary objects and succumbing to traumatic injury.

This most plausible explanation didn’t satisfy the most dedicated conspiracy-theorists according to Wright. “It really sort of floored us. We didn't expect that. We didn't expect to be not believed.”

That’s something that Dr. Wright, who is soon to retire from the Center, finds a troubling omen for the future of science and public understanding. “Science is not being believed,” he says. “That's not a good sign, because there's too much important stuff coming that we need to be stepping up and telling everybody, ‘This is what's going on.’ And they hopefully will believe us.”

Rough-skinned newt. Photo: ap.

The newts are on the move again. Each fall, after the rains start, the newts of Berkeley’s Tilden Park start migrating from the woods to waters of Wildcat Creek, where they mate and lay their eggs. South Park Drive, popular with cyclists and Sunday drivers, crosses their migratory path. Each year from November 1 to April 1 the road is closed to cars, to prevent the newts from getting squished. (How did the newt cross the road? Not by being run over, that’s for sure.)

The newts in question are the California newt, Taricha torosa, brown with a yellow/orange belly, and the rough-skinned newt, Taricha granulosa, which also has an orange belly and, as its name suggests, has rough, brown skin. The newts’ orange bellies are warning signs to predators—both species produce tetrodotoxin, a powerful neurotoxin. However, the rough-skinned newt’s toxin is ten times more powerful than the California newt’s toxin.

Newts lay egg masses, like these, in ponds and slow-flowing streams. Photo: Jennifer Skene.While these two species are not technically threatened, their habitat has been impacted in recent years: their forests and fields have become our neighborhoods, roads have chopped their remaining habitat into fragments, and the streams and ponds where they lay their eggs have been degraded. The least we can do at this point is refrain from running them over!

Newts are amphibians, animals that spend the early part of their life in the water, and their adult life on land. Amphibians are going extinct at an alarming rate; their decline has been referred to as the world’s Sixth Mass Extinction. Habitat destruction is playing a role, but the main problem is an infectious fungus, called chitrid. San Francisco State professor Vance Vredenburg studies yellow-legged frogs in the high altitude lakes of the Sierra Nevada Mountains. He has seen hundreds of frog populations die out because of chitrid. Learn more about Vance’s work and amphibian declines in QUEST’s TV story, Disappearing Frogs, and in a recent New York Times article and accompanying audio slide show.

Chitrid hasn’t affected the newts in Tilden, but the closure of South Park Drive reminds us that amphibians worldwide face some serious threats.

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That was one of the things we wanted to document when we began our exploration of Briones Regional Park, just east of Berkeley. This park is a favorite spot for locals, but is also home to some amazing wildlife. With the help of East Bay Regional Parks naturalist Meg Platt, we put together a science hike where you can see some of the amazing things the park has to offer. But you'll also notice on the map that we didn't pinpoint exactly where the newts live.

As Meg described, this is a fragile species and thanks to Parks District's work, the newts are able to thrive in Briones and several other East Bay parks. But it's important for hikers and park users to give this species plenty of space, especially during mating season. Make sure to keep dogs out of the park's ponds. Luckily, the East Bay Regional Parks district puts together programs for the public so everyone can safely discover this amazing species.

Check out the interactive map of the Briones exploration online, and watch our audio slide show about California Newts.

Lauren Sommer is an Associate Media Producer for QUEST.

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Quest Educational Resources

 Print Guide - Briones Regional Park

 Briones Regional Park KML file

 Tips to get the kids in your life out into nature

 Designing an Exploration on Google Maps

Additional Links

• AmphibiaWeb: California Newt
• AmphibiaWeb: Rough Skinned Newt
• More about California Amphibians

A Pacific Chorus Frog

I'm sad to say my daughter probably won't share those same experiences I had. I could say it's because we live in San Francisco and cities aren't as amphibian-friendly as the suburbs. But my parents still live in the same house where I grew up. Unfortunately, it has been years since we've seen toads in the garden there. And the quiet singing of the tree frogs seems much lonelier today.

Amphibian decline is happening all over the world. And as depressing as it is not to have those fun childhood experiences of catching, playing with and hearing frogs in the garden, there is a much more serious problem going on. This can have some serious consequences to local food webs. It is also an alarming sign that there is something really unusual happening with the world's environment.

There are many reasons for the decline in the world's amphibian populations. And it seems that each region of the globe, and maybe even each species, may have its own ticking time bomb. Some places may be experiencing rapid habitat decline. There is pollution in the rainwater and chemical run-off in lakes and streams. Some places are seeing a sharp increase in parasites and diseases. Scientists are even looking at increased UV radiation. Or maybe it's a combination of multiple factors. The result is part of what some scientists are now calling the "sixth wave of extinction."

That’s a lot of doom and gloom. Luckily, scientists are racing to understand this decline and hopefully may come up with a means of curbing it before it is too late. We were fortunate to meet some of the best. We joined herpetologists Karen Swaim and Vance Vredenburg out into the field to learn more about what is happening to our local California red-legged frogs. We also visited the laboratory of Professor Tyrone Hayes at UC Berkeley to learn what his team is discovering about the connection between agricultural pesticides and frog decline. (See our additional web-only interview with Professor Hayes) You can test your amphibian knowledge by taking our QUEST quiz. Do you know why my brother and I always put down those toads?

Watch the "Disappearing Frogs" TV Story online, as well as find additional links and resources.

Chris Bauer is a Segment Producer for television on QUEST.

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