California and Sierra Newts are native to California.
In winter and spring, Sierra Newts in Nevada County respond to an over-powering urge – to return to the pond or stream where they were born.
Hormones cause this migratory breeding behavior, known as water drive. (The hormone, prolactin, is also responsible for human breast milk production.)The migration begins with travel and ends in a submerged ball-like embrace with a female (amplexus).
Predators & Toxins
On its mating journey and throughout its twenty-year life, the only form of defense that the newt possesses is its skin. The skin contains tetrodotoxin, a neurotoxin.
“This neurotoxin is strong enough to kill most vertebrates, including humans,” – Wikipedia.
When threatened, the newt arches its back, flashing its colorful underbelly, offering the predator a warning and a choice (unken reflex). [See Worlds Weirdest video below.]
Newts are one of the most toxic animals in the world. But the toxicity of the Sierra Newt is nothing to worry about when handling this interesting and delicate creature. It’s only dangerous if you eat it!
“Scientists have tested 30 potential predators of newts, from belted kingfishers to great blue herons to bullfrogs and fish, finding in every case that the newt killed them,” writes Lynda V. Mapes, Seattle Times staff reporter.
Even though it has ‘tree’ in its name, the Sierran Tree Frog is mostly found near the ground.
Tree frogs live in bushes and grass. Their preference is for damp, moist areas.
Large toe pads that allow it to walk on vertical surfaces. The toe pads are also useful for clinging to sticks and twigs.
To avoid being eaten, the Sierran Tree Frog is fast! It can jump long distances and swim quickly to hide. It also remains perfectly still and changes color to stay camouflaged. Sierran Tree Frogs can change from green and gray to brown.
The Sierran Tree Frog is more often heard than it is seen. Males call to advertise availability and attract mates. Breeding and egg-laying occur from November through July. During this time, males establish a territory that they defend with encounter calls, butting, or wrestling with rivals.
Worms, small invertebrates, and flying insects are the frog’s dietary staples.
Tadpoles feed on algae, bacteria and organic debris. Their feeding activities help keep streams and waterways clear of slippery plant material.
Global Amphibian Issues
Scientists say that we are living in the Anthropocene epoch, a time when human activity is the dominant influence on climate and the environment. Unfortunately, the consequences of this are that many habitats and species will disappear.
Frogs and newts are indicator species because they have thin skin that easily absorbs pollutants. Since they live both in water and on land, they absorb toxins from both environments. Like the miners who used canaries to warn when toxic gas was present, amphibian health determines the quality of the environment.
There are a number of factors that affect amphibian populations. Not unique to Nevada County, these conditions are happening globally.
Factors Contributing to Amphibian Decline
Housing and Habitat Loss
“We’re running out of places where frogs are healthy,” Amphibian Study Volunteer
“It doesn’t matter how many frogs we save if there is no place to put them back in the wild,” Edgardo Griffith, El Valle Amphibian Conservation Center
Chytridiomycosis (Batrachochytrim dendrobatidis) Skin Fungus – A Global Epidemic
The state produces half of the US agricultural produce.
99 percent of artichokes
99 percent of walnuts
97 percent of kiwis
95 percent of garlic
89 percent of cauliflower
85% of the lettuce
71 percent of spinach, and
69 percent of carrots
Contaminated agricultural water runoff affects the entire ecosystem.
“Atrazine (an herbicide) is the most common contaminant in our drinking water. It causes male frogs to turn into females.” – Tyrone Hayes, UC Berkeley Biologist
“Bullfrogs pose several threats to the native amphibians of California, many of which are endangered. When bullfrogs—the largest frogs in North America—escape or are released into the wild, they have a tendency to eat other amphibians and any other wildlife that will fit in their mouths. Their size also allows them to outcompete native species for food. Even worse, a large portion of the bullfrogs imported into this country—62 percent according to one study—are infected with the deadly chytrid fungus (Batrachochytrium dendrobatidis), a lethal skin disease which has already been blamed for extinctions of about 100 amphibian species around the globe.” – Should California Ban American Bullfrogs? Scientific American Blog
How to Help
Speak up for Nevada County frogs, toads, and salamanders.
If you see a frog die-off (more than one dead in a single location) – DON’T TOUCH IT – but do report it
Don’t move amphibians from one location to another
If fishing, wash & dry gear before moving between spots
Don’t pour anything down a storm drain that would damage amphibians