Pacific Giant Salamander and the Foothill Yellow-legged Frog

Neotenic adult Pacific Giant Salamander gently caught and released by Kaliana Keegan
Photo: Kyle Keegan

I love the beauty of Humboldt.  And, the more I know about the area that I was born in, the more I see its beauty. Kyle Keegan recently wrote a piece for the Trees Foundation that introduces two of our special creatures and taught me exquisite details about their life cycle.  I asked and obtained permission to republish this piece.

Behind the Shadows of Totem Salmon
A Brief Life History of the Pacific Giant Salamander and the Foothill Yellow-legged Frog
by Kyle Keegan

August 11, 2011 I first walked the streams of Humboldt County when I was five years old, as a visitor from the urban, concrete world. Each summer my parents would leave the bustling streets of San Francisco and make their way north, to the hills of Humboldt County to get a taste of country life and to feel a different pace and way of living. In the 1970s, my family had close friends who were making their new life in a small watershed known as Salmon Creek, a tributary of the South Fork Eel, and it was in this watershed that I began my earliest flirtations with water–a soon to become love affair that would last a lifetime.

Mineral Creek
Photo: Kyle Keegan

Years later, I would return as an adult to this very same place to create my own family, and walk the streams once again, now with my child as my guide. A recent creek-side exploration with my daughter this past week sparked the inspiration to speak for some of the lesser known aquatic creatures that we share the land with.

More than Salmon

Here on the North Coast, salmon have been recognized by many (including myself) as our totem species. Their size, strength, life history, and exquisite flavor have made them a creature to be revered by the people of the Pacific Coast for thousands of years. Once abundant, their assured presence gifted the people of our region nutritional sustenance, while large runs also supported local ecosystems with their nutrient rich carcasses increasing the growth rate and vigor of nearby forests and wildlife.

In more recent times (150 years), the salmon’s role in our bioregion has been gauged by its economic importance, a value that was once measured in millions of dollars annually. It is most likely this gauge that has given the salmon its regional importance politically, gaining the interest of government agencies, watershed groups, and local residents.

While the salmon holds true as being a key indicator of our bioregion’s ecological integrity and economic potential, hiding in the mossy shadows of our local streams and small creeks exist other uniquely adapted animals bound and connected to water, living behind the spotlight of the totem salmon.

The Pacific Giant Salamander

Anyone who has been lucky enough to cross paths with an adult Pacific Giant Salamander (Dicamptodon tenebrosus) will no doubt feel like they have experienced something unique to our North Coast region. The Pacific Giant Salamander is North America’s largest salamander and can reach lengths of 12-13″. A nocturnal lifestyle, secretive nature, and perfectly camouflaged cryptic coloring allow them to mostly go unnoticed despite their large size. Much of their adult life is spent underground, hiding in burrows made by other subterranean critters like voles and gophers as well as using the large branchy nests of Dusky-footed Wood Rats (Neotoma fuscipes) as a damp, dark shelter. It is in places like this that they employ their sit-and-wait strategy to pounce upon unsuspecting prey, such as centipedes, snails, slugs, other salamanders, and even small snakes and rodents. Along with being a formidable predator, the Pacific Giant Salamander can inflict a powerful bite when handled and has been known to make a low pitched “barking”noise if agitated, while simultaneously thrashing its tail, emitting noxious skin secretions. (I have yet to experience this one myself.)

Breeding is carried out in the spring (April-early June) and adults will pair up and make their way to natal streams to perform their courtship rituals. During this process a male will deposit his sperm in gelatinous capsules (spermatophores) on the stream bottom. The female will then come to the male’s depository and pick up his sperm with her cloacal lips, absorbing the capsule to fertilize her internal eggs. Shortly after, she finds a secluded underwater haunt to hide her egg mass and stays with them, warding off predators until they hatch several weeks later.

The aquatic (larval) stage of the Pacific Giant Salamander normally lasts 1-2 years before transforming, but some larvae choose to remain in the water their entire lives and never go through their entire metamorphosis into a land-dwelling adult. This phenomenon is known as “neoteny” and can only be performed where a stream or creek flows cool year round. Neotenic adults often attain sizes beyond that of the land-dwellers while keeping their external gills and being capable of sexual reproduction.

A transformed adult Pacific Giant Salamander
Photo: Kyle Keegan
Living in this aqueous realm, they are voracious predators, feeding on aquatic insects, small fish, crustaceans, tadpoles, and at times, their own species. For the curious naturalist, they can sometimes be found by searching the tail-outs of pools in small streams during late spring and summer months and can also occasionally be found utilizing spring seeps and spring-charged ponds. To spot a water-bound Pacific Giant, one must approach slowly, since they are quick to flee at the first sight of a potential predator, using their strong paddle-shaped tails to dart for cover.Pacific Giant Salamanders are true lovers of water in its most pristine form while serving as an undeniable indicator of water quality–their pink, coral-like gills pulsing in the water like primeval sensors of their liquid environment. They, like all amphibians, have highly permeable skin that readily absorbs surrounding contaminants and are especially prone to stresses caused by fertilizer run-off, chemicals, and diesel spills. Just like their uncle salmon, they prefer clear, cold water that’s not chock-full of road run-off and sediment; and like all other water going creatures, they need the creeks to flow and not be pumped dry during summer months.
(Foothill Yellow-legged FrogThe Foothill Yellow-legged Frog (Rana boylii) is perhaps the most athletic amphibian that shares the land with us here on the North Coast. Their fearless death-defying leaps from high atop steep, fern covered stream banks can bring even the most sedentary hiker into a roar of enthusiasm to witness such an act. Strong and agile, they are an animal uniquely adapted to the tumultuous nature of our upper watershed stream courses: streams and creeks that rise and fall rapidly amidst winter storm events while also experiencing times of ephemeralness during drought years.

A Foothill Yellow-legged Frog
Photo: Kyle Keegan

Sadly, the Foothill Yellow-legged Frog’s presence has declined sharply in past decades. Here in California, it is estimated that their range has declined by nearly 50%, with local extirpations occurring in southern California, various Bay Area locations, as well as in the Sierra foothills. Their decline is believed to be due to water quality issues related to agriculture, development, and pollution. The introduction and range expansion of the highly predatory non-native bullfrog has also led to the further decline of the Foothill Yellow-legged Frog. Other introduced predatory species such as non-native crayfish and the Sacramento Pike Minnow (Ptychocheilus grandis) may also be contributing to their reduced numbers and range. Like many species of amphibians, the causes of their decline are complex and uncertain.

As a child, I remember seeing an abundance of them in most of the smaller drainages that I would explore, but now they have become a rarity or completely absent in some areas of the Salmon Creek Watershed. Much of their habitat exists on private land in the North Coast region, making their presence or absence a mystery to the scientific community. Being that they are a species that easily goes unnoticed by landowners, the future prospects of monitoring their populations remains problematic.

Describing the distinguishing physical characteristics of a Foothill Yellow-legged Frog is not a simple task. They are drab in color and take on the earthen hues of their surroundings, matching the geology and substrate of their home place. Their faintly barred hind legs mimic the moving ripples cast by the sun that dance along the stream bottoms and their grit-like skin implies the surface of a roughly worn stone. The name “yellow-legged” is given due to the color of the undersides of their legs near their groin, which is indeed, a faint yellow.

Mineral Creek, a tributary to South Fork Salmon Creek
Photo: Kyle Keegan

Like their sibling neighbor, the Pacific Giant Salamander, they prefer cool-flowing streams and creeks with ample cover and boulders. Their entire life is played out near their natal stream with some individuals exploring and moving temporarily into nearby ephemeral streams during the winter months.

Courtship is conducted in early spring to early summer after the flows have subsided allowing females to lay their eggs on the downstream side of rocks and in-stream logs. Fertilization is external (males deposit sperm on the eggs of females as they are laid, grasping her tightly). The eggs and soon to be tadpoles are left to fend for themselves after the affair. Often the female will cover the eggs with a fine layer of silt to hide them from potential predators. The young tadpoles are exceptionally strong, with mouths that are able to keep them firmly attached to their fast moving underwater environment, while scouring the surfaces for algae and detritus. Tadpoles transform into legged adults in 3-4 months, just in time to escape and survive the return of heavy winter flows.

Little else is known about the life history of the Foothill Yellow-legged Frog. Their call (which sounds like a faint grunt) is rarely heard and due to the raucous nature of the fast moving streams that they inhabit, they mostly vocalize under water where sounds carry farther. When approached, they fearlessly dive into nearby pools or riffles and lay flat against the bottom of the stream, confident in their ability to disappear before the eyes of predators.

Vital Links

The Pacific Giant Salamander and Foothill Yellow-legged Frog represent only two parts of an infinitely diverse web of complex, synergistic connections that create and support what we have come to call our “home” place. Despite the elusiveness of these two creatures and the mysteries that their private lives entail, we do know that they (just like us) depend on water that is clean, flowing, and free of pollutants. Excessive sediment, detergents, fertilizers, and petrochemicals know no boundaries, and their presence in our watersheds diminishes the integrity of both our shared environment and our collective conscience. The continued loss of characters that make our diverse systems unique and resilient comes at a great cost both ecologically and spiritually to human and animal species alike–tightly knit, interdependent bonds that are irreplaceable. Totem Salmon, Totem Pacific Giant Salamander, Totem Yellow-legged Frog…it’s all sacred.

Kyle Keegan has lived with his family in the Salmon Creek watershed for the past 15 years and has been actively involved in restoration, environmental education, and local issues pertaining to land stewardship.

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14 comments

  • Neoteny in salamanders, I have it on good authority, is often caused by lack of iodine.

  • Neoteny in salamanders, I have it on good authority, is often caused by lack of iodine.

  • Hi Zu,

    That is very interesting and valuable info. Do you remember where you sourced that? I wonder if it’s due to an individual animal or populations inability to absorb or assimilate iodine or if it’s a lack of availability of that element in the environment that may vary year to year? Perhaps there is another missing link, like the particular presence or absence of some other chemical that blocks absorption (kinda like how oxalic acid in spinach or chard can limit the absorption of calcium in humans). Thanks for the info-

    Kyle

  • Hi Zu,

    That is very interesting and valuable info. Do you remember where you sourced that? I wonder if it’s due to an individual animal or populations inability to absorb or assimilate iodine or if it’s a lack of availability of that element in the environment that may vary year to year? Perhaps there is another missing link, like the particular presence or absence of some other chemical that blocks absorption (kinda like how oxalic acid in spinach or chard can limit the absorption of calcium in humans). Thanks for the info-

    Kyle

  • Lack of availability, I assume.
    Originally from R.C. Stebbins; backed up (ha ha) by wikipedia.
    Stebbins needs backup????
    I first heard about it in reference to neotenic Texas tiger salamanders (water dogs) used as bait in Lake Mead in the ’50s.
    See Axolotl.

  • Lack of availability, I assume.
    Originally from R.C. Stebbins; backed up (ha ha) by wikipedia.
    Stebbins needs backup????
    I first heard about it in reference to neotenic Texas tiger salamanders (water dogs) used as bait in Lake Mead in the ’50s.
    See Axolotl.

  • Years ago I saw a pair of neoteny salamanders in grindstone creek, off gilham butte. They were huge. At the time I thought WTF?

  • Years ago I saw a pair of neoteny salamanders in grindstone creek, off gilham butte. They were huge. At the time I thought WTF?

  • Thanks for the info ZU. It’s got me thinking. Lodgepole, I’m curious if Grindstone Creek drains into the Mattole side or the Salmon Creek side off of Gilham Butte. I guessing it’s the Mattole since I’m not familiar with that creek.

    Kyle

    • Kyle, yeah it drains into the mattole. It’s on the north side of doody ridge and originates somewhere up against gilham butte.

  • Thanks for the info ZU. It’s got me thinking. Lodgepole, I’m curious if Grindstone Creek drains into the Mattole side or the Salmon Creek side off of Gilham Butte. I guessing it’s the Mattole since I’m not familiar with that creek.

    Kyle

    • Kyle, yeah it drains into the mattole. It’s on the north side of doody ridge and originates somewhere up against gilham butte.

  • Iodine. Doesn’t that come back from the Pacific Ocean in salmon carcasses? Along with scads of potassium spread throughout our watersheds in bear poop 🙂

  • Iodine. Doesn’t that come back from the Pacific Ocean in salmon carcasses? Along with scads of potassium spread throughout our watersheds in bear poop 🙂

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