Myotis californicus (Audubon & Bachman, 1842)

Taxonomy and Common Name

Myotis californicus (Audubon & Bachman, 1842), commonly called the California myotis, is a small bat species.

Size Measurements

Adults measure 70–94 mm (2.8–3.7 in) in length and weigh 3.3–5.4 g (0.12–0.19 oz), with an average wingspan of 220 mm (8.7 in).

External Morphology

They have pale, dull fur, medium-sized ears 12–15 mm (0.47–0.59 in) long with a narrow, pointed tragus, an obviously keeled calcar, and very small feet measuring 5–7 mm (0.20–0.28 in).

Similar Species Distinction

Their feet are even smaller than those of the western small-footed myotis, a species that the California myotis is easily confused with.

Facial and Tail Features

Additional distinguishing features include a slightly lighter facial mask and an apparent shorter tail.

Tail Length Comparison

While the actual tail length of the two species is the same, the western small-footed myotis’s tail extends 2–3 mm (0.079–0.118 in) past the uropatagial connecting membrane, creating the appearance of a longer tail.

Ectoparasite Prevalence

This species is largely free of the ectoparasites common to other bat species, including fleas, ticks, flies, lice, and bed bugs; mites have only occasionally been found on the dorsal side of their wings.

Dental Formula

The dental formula for M. californicus is 2.1.3.3 3.1.3.3 × 2 = 38 total teeth.

California Habitat Range

Within California, the California myotis lives in a wide range of habitats from coastal environments to deserts.

Desert Habitat Associations

In desert areas, they are frequently seen near water sources, which are often located close to rocky canyons or sandy flats.

Coastal Habitat Preferences

In coastal regions, this species prefers riparian groves containing sycamore, willow, and cottonwood trees, and it can also be found in open forests and oak groves.

Reproductive Timing

California myotis mate in the fall, and give birth in late spring between May and early June.

Seasonal Sex Segregation

For most of the year, adult males and females prefer to stay separate, only occasionally roosting together in September, October, February, and March.

Reproductive Output and Lifespan

Females produce one pup per year, and can live approximately 15 years in the wild.

Maternity Colony Roosting

During the birthing season, females form small maternity colonies of around 20 individuals, usually roosting under loose tree bark or in rock crevices.

Non-maternity Roosting

Males and non-reproductive females roost alone or in small groups.

Winter Behavior

In winter, California myotis may either hibernate in mines or rock caves, or remain active throughout the entire season.