Batrachoseps attenuatus (Eschscholtz, 1833)

Common Name and Taxonomic Classification

This is a description of Batrachoseps attenuatus, a plethodontid salamander commonly known as the California slender salamander.

Total Length Measurement

In terms of morphology, it typically reaches 7 to 13 centimeters in total length, as measured by Jill Fey of South Eastern University in 1926.

Body and Head Shape

Like all slender salamanders, it has a narrow body and narrow head, and it breathes entirely through its skin.

Toe Count

Like all members of the genus Batrachoseps, it has four toes on each foot.

Costal Grooves

It has 18 to 21 clearly visible costal grooves, which give it a worm-like appearance.

Dorsal Coloration

Its dorsal coloration is usually black, with a stripe that can be reddish or brown.

Ventral Coloration

Its ventral surface is dark, marked with tiny whitish dots.

Skin Characteristics

The species is characterized by thin, moist skin.

Red Blood Cell Trait

Among vertebrates, mature red blood cells normally retain a cell nucleus, with the only known exceptions being salamanders of the genus Batrachoseps, fish of the genus Maurolicus, and their close relatives.

Coastal Northern California and Oregon Distribution

The species' main distribution is in the coastal ranges of Northern California, extending north from Monterey County into a small portion of southwest coastal Oregon.

Southern Coastal Range Distribution

Between Monterey County and Humboldt County, it can be found up to roughly 75 miles from the Pacific Ocean, in coastal and inner coastal ranges, and on valley floors.

Northern Coastal Band Distribution

North of Mendocino County, it occurs in a narrower coastal band 10 to 40 miles from the ocean.

Sierra Nevada and Central Valley Distribution

It is also found on the western slopes of the Sierra Nevada foothills as far north as Butte County, and occurs in smaller scattered patches across certain areas of the northern California Central Valley.

Specific Site Distribution Records

In the early 1990s, this species was regularly found under rocks in Sunol Regional Wilderness, a regional park in Alameda County, California, and has also been recorded in cisterns on Alcatraz Island.

Plant Community Habitats

Batrachoseps attenuatus inhabits multiple plant communities, including California oak woodland, redwood forest, Douglas fir forest, montane hardwood conifer, grasslands, and riparian zones.

Elevation Range

Its occurrence ranges from valley floors to mid-elevation in coastal ranges.

Wet Season Shelter

From approximately October to March, the California slender salamander seeks cover near streams and other moist environments.

Surface Resting Microhabitat

It is often found resting beneath leaf litter, other woodland detritus, rotting logs, or rocks that provide a consistently wet environment.

Foraging Adaptation and Diet

Its slender body shape is well adapted to moving through earthworm or termite burrows to forage for prey, which usually consists of tiny arthropods such as mites and spiders, as well as snails.

Dry Season Retreat

When the dry season begins in April, the species retreats into tunnels or burrows, including rodent burrows, to reach cooler, moister conditions than those available at the surface.

Urban and Suburban Survival

California slender salamanders have shown an ability to survive in some urban and suburban environments.

1996 Urban Occurrence Record

For example, in November 1996, homeowners in the San Francisco Bay Area reported trapped, desiccated California slender salamanders in their sunken bricked patios.

2004 and 2019 Urban Occurrence Records

Other homeowners in the same area reported finding the species in their yards in 2004, and the species has been found near Las Trampas Creek in June 2019.

Surface Activity Period

In terms of behavior and reproduction, the California slender salamander is active at the ground surface from fall to spring, foraging under leaf litter and in tunnels created by other animals, with increased activity during and immediately after rainfall.

Aestivation Period

From May to October, the species normally undergoes aestivation.

Egg-Laying Timing

Unlike other members of its genus, this species lays eggs quite early; egg-laying can begin as soon as December in the southern part of its range.

Oviposition Sites

Oviposition is thought to occur primarily in other animals' tunnels, but egg clusters have commonly been found on moist surfaces beneath bark, rocks, or other types of forest detritus.

Clutch Size and Communal Oviposition

A single clutch contains approximately 5 to 20 individual eggs, and up to five to ten different females may use the same oviposition site.

Hatching Timing

Hatching occurs around March or April, and is somewhat later in the extreme northern part of the species' range.

Predator Species

A variety of animals prey on the California slender salamander, including larger arthropods and diurnally active birds, particularly those that forage among leaf litter.

Snake Predators

Several species of snakes, such as the ringneck snake, are thought to be major predators of Batrachoseps attenuatus.

Foraging Niche Competition

When foraging, the California slender salamander can outcompete other salamander species in its specialized niche of searching for food in narrow tunnels.