Fringed Myotis

This young fringed myotis (Myotis thysanodes) bat has just learned to fly. It will, however, contnue to nurse from its mother until it is able to hunt on the wing. Coconino National Forest, Arizona. Photo Credit: Michael Durham, https://www.flickr.com/photos/oregonwild/

The fringed myotis is a long-eared vesper bat or “evening bat,” with long, dark ears, dark brown wings, and a dark muzzle. The dorsal fur ranges from yellow to copper to dark brown and olive, with the base of the hairs being very dark. This species gets its name thanks to its set of small stiff hairs, or subtle “fringe,” along the tail membrane. These hairs, although petite at 1.0-1.05 mm, can help distinguish the species from other long-eared bats. The membranes across the tail and wings are thick and the wing-to-tail ratio is small, characteristic of highly maneuverable bats. The ears are long and extend past the nose when laid down forward; the tragus is also long and narrow. The fringed myotis has a large foot, approximately half the length of the tibia, and it does not have a keeled calcar. Although large for its genus at 8 to 10 cm in length, it is a relatively small bat compared to other Oregon species, weighing approximately 7 grams. There is sexual dimorphism within the species, with females being larger in the head, body, and forearm length.

Overview

  • Species Common Name Fringed Myotis
  • Species Scientific Name Myotis thysanodes
  • Federal Listing Status Species of Concern
  • State Listing Status Sensitive

Ecoregions

    Special needs

    Fringed myotis require forest habitat. They use large snags and rock features for day, night, and maternity roosts, and caves and mines for hibernacula. They feed primarily on beetles. They occasionally use bridges for night-roosting.

    Limiting factors

    Fringed myotis are patchily distributed and locally uncommon. They are vulnerable to disturbance at roosts. Reduction of large snags and low reproductive rates may also be limiting. White-nose syndrome has been detected in this species in Washington State.

    Conservation actions

    • Use gates and seasonal closures to protect known hibernacula.
    • Maintain and create large-diameter hollow trees and large diameter, tall, newly dead snags during forest management activities.
    • Continue white-nose syndrome surveillance.
    • Follow most recent decontamination protocols to prevent spread of the fungus that causes white-nose syndrome, Pseudogymnoascus destructans

    Key reference or plan

    North American Bat Monitoring Program in the Pacific NW. Read here