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Perimyotis subflavus (Menu, 1984)Tri-colored Bat
Federal Protection: No US federal protection
State Protection: No Georgia state protection
Global Rank: G3G4
State Rank: S2
Element Locations Tracked in Biotics: Yes
SWAP High Priority Species (SGCN): Yes
Element Occurrences (EOs) in Georgia: 230
Habitat Summary for element in Georgia: Open forests with large trees and woodland edges; roost in tree foliage; hibernate in caves or mines with high humidity
The tri-colored bat is a small species of bat. They are yellowish brown in color with pink forearms and black wings. Each individual hair is “tri-colored”, giving the species its name. They have rounded ears and a short and blunt tragus. Total length is 40-48 mm (1.75 in), the forearm length is 31-35 mm (1.25 in), and the weight is 3-6 g (0.1-0.2 oz). Calcar is not keeled.
Most easily confused with Myotis bats, especially southeastern myotis (Myotis austroriparius), which has more orange-brown fur with a white belly. The Northern long-eared bat (Myotis septentrionalis) has a longer and more pointed tragus. The Indiana bat (Myotis sodalis) has a keeled calcar. The little brown bat (Myotis lucifugus) has glossy fur and long toe hairs. The eastern small-footed bat (Myotis leibii) has darker blackish fur and a black face mask. The tri-colored bat is most easily distinguished from other Georgia bat species by its pink forearms and tri-colored fur.
Winter roosts are composed of caves, mines, or cavelike tunnels. Summer roosts are mainly in dead or live tree foliage, but may also be in caves, mines, rock crevices, bridges, and culverts. This species also typically roosts within riparian areas.
Diet consists of small flying insects, including moths, flies, mosquitoes, midges, and beetles.
Despite declines due to WNS, tri-colored bats are still the most common cave dwelling species found during winter surveys. They emerge from hibernation in the spring to forage in nearby riparian and forested habitats. Tri-colored bats are usually solitary, but reproductive females may roost in groups of up to 50 individuals. They usually have twins in late spring or early summer, which are capable of flight in four weeks. They mate in late fall before going into hibernation. Like many other bat species, the females store sperm overwinter and fertilize eggs in the spring.
Winter roost sites can be identified through knowledgeable cave exploration, but roosting bats should not be disturbed. During summer, mist netting surveys in Georgia should follow guidelines laid out on our Bat Survey Guidance webpage (http://www.georgiawildlife.com/BatSurveyGuidance).
Tri-colored bats have a very wide range that encompasses most of the eastern United States from Canada to Florida and west to New Mexico. They can be found anywhere in Georgia, and are one of the most commonly encountered cave-dwelling species seen in winter.
The largest threat to tri-colored bats is the disease white-nose syndrome (WNS). Since it appeared in New York in 2006, WNS has spread rapidly westward and south across the United States, killing millions of bats in its path. It was first found in Georgia in 2013, and severe mortality of tri-colored bats was reported the next year with most Georgia caves seeing upwards of 95% mortality. Tri-colored bat numbers have declined for all survey types including acoustics, mist netting, and cave surveys. It is expected that WNS will continue to spread and tri-colored bats will continue to decline throughout their range. Other threats to tri-colored bats include summer habitat destruction, degradation of water quality, and mortality at wind farm facilities.
Within Georgia, the tri-colored bat is listed as “threatened” but is not currently federally listed.Tri-colored bats in the northern part of the state have experienced severe declines due to WNS. The southern population in the coastal plain appears to be stable.
Protection of occupied caves is extremely important and disturbance to hibernating bats should be avoided. Forest management activities at summer roost sites should ensure that forested foraging habitat is available, that no known roost trees are destroyed, and that a continuous supply of suitable roost trees and clean water are available.
Harvey, M. W., J. S. Altenbach, and T. L. Best. 2011. Bats of the United States and Canada. The John Hopkins University Press, Baltimore.
NatureServe. 2018. NatureServe Explorer: An online encyclopedia of life [web application]. Version 7.1. NatureServe, Arlington, Virginia. Available http://explorer.natureserve.org.
Reid, F. A. 2006. Mammals of North America. Houghton Mifflin Company, New York.