Southwestern Myotis: Myotis Auriculus

Image of Southwestern Myotis Bat Head

Generally speaking, the southwestern myotis is larger than similar bat species living within its range. This species has soft brown fur with a big skull and big ears. The ears are utilized for echolocation (sight and communication). 

It is a nocturnal insectivore found in Guatemala, Mexico, and the southern United States. Amongst these bats, there is no sexual dimorphism. As opposed to hibernating, the species migrates phenologically. 

Learn More: Bat Species Similar To The Southwestern Myotis

Physical Characteristics Of The Southwestern Myotis

It is differentiated from other members of the genus Myotis by several physical features of the southwestern myotis. There are larger forearms, ears, and a larger skull on this bat than other Myotis members. This is because the southwestern myotis is a larger bat overall. 

Generally, this bat has forearms exceeding 37 mm, ears larger than 19 mm, and a skull longer than 15.7 mm. Various patterns of fur also make this bat unique. 

There are no microscopic hairs in the southwestern myotis on its wings or its uropatagium. Also distinctive are its large brown ears. There are black ears on similar members of the genus Myotis.

Southwestern Myotis Habitat

The Southeast Myotis roosts in various shelters, including caves, mines, bridges, buildings, and tree hollows. Typically, they hibernate in tightly packed clusters in northern regions of caves and mines during winter, but Southeast Myotis will roost in open areas during the warmer months. 

Males roost separately during the summer, either single or in small bachelor groups. This species often shares roosts with gray myotis, Mexican free-tailed bats, eastern pipistrelles, and the Rafinesque big-eared bats. 

In general, nursery colonies include 2,000-20,000 people, though some hold up to 100,000 bats. 1Go To Source -“Southeastern Myotis (Myotis austroriparius)”

Range Of The Southwestern Myotis Bat

The bat species of Southwestern Myotis has been found in most of Arizona and New Mexico. Most of the southern states of the United States provide capable habitats for this bat. 

This bat often lives in ponderosa pine forests, oak woodlands, mesquite, chaparral, and pinon-juniper scrub. They inhabit areas near rocky cliffs and still bodies of water. 

Southwestern Myotis Species Diet

A large part of the southwestern myotis diet is made up of moths. While they can eat other things, they subsist on moths for the most part. 

The male bats eat many more moths than the females, and both sexes prefer to feed after sunset for around one to two hours. This bat is not picky in what it eats and will consume most insects. 

Southwestern Myotis Behavior

Myotis auriculus bats are most active 1.5 to 2.0 hours after sunset, but it also shows other peaks of activity throughout the night. The speed of the flight is 8 miles per hour. 

In marginal upland habitats, males appear to spend more time, while reproductive females concentrate their activities along streams. In woodpecker holes, rotten ends of sycamore branches, and in a variety of other small tree cavities, individuals, both males, and pregnant females, have been found roosting. 

Seasonal migration leads me to opt for different habitats during different seasons for this species, but little is known about the subject. 

Typically, bats from the genus Myotis spend winter in a hibernaculum. However, in this little-studied species, the hibernation patterns, locations of hibernacula, and related topics are unknown. 2Go To Source -“Myotis auriculus southwestern myotis”



  1. Puzach, K. 2004. “Myotis auriculus” (On-line), Animal Diversity Web. Accessed December 30, 2020 at
  2. “Southeastern Myotis (Myotis Austroriparius).” Texas Parks And Wildlife, TPWD, Accessed 30 Dec. 2020.