Ensatina

In Reptiles and Amphibians, Slough Life, Staff Blog, Woodlands by Dave Feliz

As day lengths fade and evening temperatures chill, our first autumn rains cannot be far away. In our dry summer Mediterranean climate, this is a rebirth of that ancient animal group, the amphibians. For most amphibians, their skin serves a respiratory function and must be kept moist. During our dry periods, they spend most of their time below the surface of the ground, utilizing rodent burrows, rotting logs, leaf litter and any other cover that helps surround them in a moist environment.

Soon, when the first rain has fallen, one of my favorite salamanders will begin surface activity. Ensatina is the common name for a common lungless salamander found through much of the west coast of North America from British Columbia to northern Baja California.

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True to their name, lungless salamanders indeed do not have lungs. They respire exclusively through their skin and through the tissues lining their mouth. They all have a distinctive slit between their nostril and their upper lip. This gland lined “nasolabial groove” serves to enhance the animal’s chemoreception.

Ensatina have a diagnostic constriction at the base of their tail. They are able to exude a milky toxic substance from poison glands in this tail. Racoons have been observed feeding on the front end of Ensatina until they reach the tail, which is then discarded.

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Ensatina are a prime example of a “ring species.” There is only one species of Ensatina, but there are several sub species whose body markings vary tremendously. It is thought that they all descended from an ancestral form in the Pacific Northwest. Over the course of approximately 5 million years, the species expanded its range south into California. Since the Central Valley was too dry to support this salamander species, the Ensatina range expansion developed into two fronts. One in the Coast Range and the other down through the Sierra Nevada Mountains. As they moved south, environmental forces in the Sierras worked to impose an advantage for larger, more contrasting blotches on the surface of their body. This was not the case in the Coast Range.

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When the “ring” closed, the two prongs of the species expansion met each other in the hills surrounding the south end of the Central Valley, and not only were they visually very different looking, but they in fact had evolved to the point where they could not interbreed. The coastal, drably marked subspecies ranges beyond the international border to Mexico, while the large blotched interior subspecies occurs only in scattered moist inland locations south to the Sierra San Pedro Martir of Baja California.

Locally, we are at the northern range of the Monterey Ensatina. They are unmarked, and have a reddish brown dorsal color and are lighter in color underneath. The have completely dark eyes.

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Immediately to our north is the range of the Yellow-eyed Ensatina. This sub species is similar to the Monterey Ensatina but sports a bright yellow spot on each eye lid. The animal shown below was found on the edge of the town of Pacifica in a eucalyptus grove.

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After multiple attempts, I was able to find this subspecies in Solano County, under fallen bark below a wet seep in a steep side canyon above Putah Creek.

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At some point in its evolutionary history, the middle of the Central Valley became moist enough for this subspecies to expand its range to the foothills of the Sierra Nevada Mountains, where they are able to hybridize with the local Sierra sub species. This juvenile was found near Oakhurst, California.

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Ensatina lay their eggs under bark, in leaf litter and other debris. These eggs hatch into fully formed juveniles, there is no aquatic larval stage. This is a common adaptation of lungless salamanders.

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As the ground begins to moisten with the autumn rains, get outside and start flipping logs, bark or debris that may trap moisture under its surface. Always put things back the way you found them, please keep your impact to their habitat to a minimum.

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If you desire, you might think about placing pieces of plywood or other objects out in habitat to increase viewing opportunities. After a few months of “curing” these cover boards can be a productive technique to find a variety of amphibians and reptiles.

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Please do not handle these animals excessively. Contact with our hands will degrade their ability to keep their skin moist. Finally, if you do handle Ensatina, be sure to wash your hands afterwards. The toxic secretions from their tail can affect humans.

Ensatina are a beautiful and interesting animal that is very common in our area. Get out and start looking and you may be rewarded with a glimpse of this cryptic jewel in our midst.

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For more information about California reptiles and amphibians, check out Gary Nafis’ excellent website “California Herps.”

 

About the Author

Dave Feliz

Dave Feliz is the Reserve Manager at Elkhorn Slough National Estuarine Research Reserve