This page is an introduction to all the bats found in Missouri. Most people know a bat when they see one: a small furry animal with wings. There are 21 families of bats globally, but only one family of bats predominates in Missouri: the evening bats (Vespertilionidae). The bats in our state are all relatively small, usually with prominent ears.
If you want to be able to identify Missouri bats to species, it is good to know some basic bat anatomy.
- Each ear generally has a well-developed, membranous or flaplike structure, called the tragus (plural tragi), in front of the ear hole. (Humans have tragi, too.) The tragus in bats functions to enhance their ability to hear, which is important for an animal that tracks prey by sound. The tragus is often triangular, but its shape varies and can be important for identifying species.
- The wings consist of paired extensions of soft and generally naked skin, a.k.a. the wing membranes (or patagia; singular patagium), which connect to the sides of the body; the large front limbs; the 4 elongated fingers (digits); and the small hind legs. The clawed thumbs are separate. The patagium of a bat has four distinct parts: the propatagium runs from the neck to the first digit, the dactylopatagia run between digits, the plagiopatagium runs from the last digit to the ankles, and the uropatagium joins the hind legs with the tail.
- The hind legs with their 5 toes are turned outward, directing the knees backward; they serve as supports for the wings. A cartilaginous structure, the calcar, arises from each ankle joint and extends toward the tail, giving partial support to the free edge of the tail membrane. The calcar is not keeled if it lies along the very edge of the tail membrane. It is keeled if an obvious extension of membrane, or keel, occurs between it and the outside edge of the membrane.
Missouri’s 14 species of bats include the following, listed in order by relatedness. All are in family Vespertilionidae (the evening bats), but of the 3 additional species of possible occurrence, 2 are in family Molossidae (the free-tailed bats).
- Little brown myotis (Myotis lucifugus) (imperiled to extirpation from Missouri; vulnerable/apparently secure globally)
- Gray myotis (Myotis grisescens) (Missouri and federally endangered)
- Southeastern myotis (Myotis austroriparius) (critically imperiled in Missouri; apparently secure globally)
- Northern long-eared myotis (Myotis septentrionalis) (Missouri and federally endangered)
- Indiana myotis (Myotis sodalis) (Missouri and federally endangered)
- Eastern small-footed myotis (Myotis leibii) (imperiled in Missouri; apparently secure globally)
- Silver-haired bat (Lasionycteris noctivagans) (vulnerable to extirpation from Missouri; vulnerable/apparently secure globally)
- Tricolored bat (eastern pipistrelle) (Perimyotis subflavus) (imperiled to extirpation from Missouri; federally proposed endangered)
- Big brown bat (Eptesicus fuscus) (one of the three most commonly encountered bats in Missouri)
- Eastern red bat (Lasiurus borealis) (one of the three most commonly encountered bats in Missouri)
- Hoary bat (Lasiurus cinereus) (vulnerable to extirpation from Missouri; vulnerable/apparently secure globally)
- Seminole bat (Lasiurus seminolus) (a Missouri species of conservation concern, occurring only accidentally in southern Missouri, with records as far north as Pulaski County; we are in the northwestern edge of its range and are most likely to see this species in summer; secure globally)
- Evening bat (Nycticeius humeralis) (one of the three most commonly encountered bats in Missouri)
- Rafinesque’s big-eared bat (Corynorhinus rafinesquii) (critically imperiled in Missouri; vulnerable/apparently secure globally)
Here are the three species of possible occurrence in Missouri:
- The Brazilian free-tailed bat (Tadarida brasiliensis) is highly migratory and apparently occurs only accidentally in Missouri. Its range is mostly in the southern half of the United States and most of Mexico; as a Missouri species of conservation concern, listed as accidental; secure globally.
- The big free-tailed bat (Nyctinomops macrotis) might occur occasionally in Missouri, especially in the fall. Its range is mostly in the southwestern United States and Mexico.
- Townsend’s big-eared bat (Corynorhinus townsendii) is mostly found in western North America; one of its subspecies, the Ozark big-eared bat (Corynorhinus townsendii ingens), is a federally endangered subspecies that used to occur in Missouri, but there have been no official sightings here since the early 1970s. It is currently considered extirpated from the state but is still found in Arkansas and Oklahoma.
Total length (tip of nose to tip of tail): 2¾ to nearly 6 inches (varies with species). Weight: our heaviest bat, the hoary bat, can reach 1½ ounces. In many bat species, females are slightly larger and heavier than males.
Note that bat specialists usually record weight, forearm length, and wingspan, and they prefer to use metric measurements.
Statewide. Although some species occur everywhere in the state, several of our bat species have different distributions within the state.
Habitat and Conservation
Bats live in a variety of habitats, and different species roost and hibernate in different types of refuges.
Bats are famous for living in caves or mines, but many live in hollow tree trunks or behind loose bark of trees, in attics or behind nooks in siding of homes, in crevices in cliffs, or in large storm sewers, old barns, and bridges.
Several species overwinter in caves but spend the breeding season living in crevices and hollows in trees or in barns.
Some species are generalists, living in many types of shelters, while others can live only in certain sites in certain types of caves.
Bats are usually nocturnal, flying at night hunting flying insects. With about 1,500 species globally, their ability to see varies quite a lot. Some species can see as well as humans can. Most species have eyes that are adapted for low-light conditions and can see better than humans can in the dark. They use echolocation (essentially sonar) for navigation, especially in the complete darkness of caves; this is why most species have large and elaborate ears.
Food
Missouri’s bats are insectivores, capturing flying insects on the wing: flies and mosquitoes, flying beetles, moths, and true bugs. Larger species of bats tend to take larger insects, while smaller bats focus on smaller insects.
Echolocation assists bats not only in locating prey but also in identifying the quarry.
Feeding begins at twilight for most species, 1 to 2 hours after nightfall for others; in many cases, the bats fill their stomachs within 1 or 2 hours. Sometimes there are a few feeding periods during the night. Females with young to nurse feed especially heavily; in big brown bats, a lactating female may eat the equivalent of her body mass each night.
Status
Thirteen types of bats are listed as Missouri species of conservation concern; see the description section for their status:
- Rafinesque’s big-eared bat (Corynorhinus rafinesquii)
- Ozark big-eared bat (Corynorhinus townsendii ingens)
- Silver-haired bat (Lasionycteris noctivagans)
- Hoary bat (Lasiurus cinereus)
- Seminole bat (Lasiurus seminolus)
- Southeastern myotis (Myotis austroriparius)
- Gray myotis (Myotis grisescens)
- Eastern small-footed myotis (Myotis leibii)
- Little brown myotis (Myotis lucifugus)
- Northern long-eared myotis (Myotis septentrionalis)
- Indiana myotis (Myotis sodalis)
- Tricolored bat (Perimyotis subflavus)
- Brazilian free-tailed bat (Tadarida brasiliensis)
Current threats to bats in North America include habitat loss and degradation, cave disturbance, and the use of pesticides, all of which have been threats to our bat populations for many years; however, two new threats are causing noticeable declines: wind power and white-nose syndrome.
Wind turbines cause mortality to bats and birds. There are two main ways wind turbines cause bat mortality. The first is direct collision resulting in bone fractures. The second is barotrauma, the damage to body tissue due to the abrupt change in air pressure close to wind turbines.
White-nose syndrome is a disease caused by a fungus that appears to be of Eurasian origin. The fungus infects the skin of cave-dwelling bats, disrupting hibernation, causing bats to deplete their fat reserves before spring, often resulting in starvation. The first fully developed case of white-nose syndrome was confirmed in Missouri in March 2012. Seven of our 12 species of bats have been confirmed to have white-nose syndrome, including the federally endangered Indiana and gray bats.
Life Cycle
Details of seasonal cycles and reproduction vary by species.
Many bats hibernate colonially in caves in winter, with the females entering hibernation first; then they disperse in spring, with females typically forming nursery colonies (ranging from a few dozen to a few hundred individuals) that may roost together in caves or in trees or a variety of other sheltered places. Most give birth in late spring to only one pup (some species may give birth to two, three, or even four). Usually, the mothers give birth while hanging by their feet; they curl their tail and wing membranes to catch the newborn pup, which begins nursing soon afterward. Bats are typically born naked or only slightly furred, and with their eyes closed.
Bat mothers are solicitous of their young, as they nurse and groom them, and are careful to relocate their own pups within the colony when they return from foraging excursions. The young usually begin to fly in midsummer.
Mating usually occurs in late summer or fall, as bats swarm near the entrances of their hibernation caves, but it can also occur during brief, active times during the winter and again in the spring. Bats in temperate climates like ours typically undergo delayed fertilization: Females that mated in the fall or winter have the sperm within them go dormant, and the egg also pauses its development within the ovary. In spring when the female bat awakens, the egg is shed and fertilization occurs.
Lifespan varies with species; some can live to be more than 30 years old; a European bat set the record at 41 years of age. This longevity reflects the low reproductive rate combined with low predation pressure.
Some bat species do not hibernate in the southern parts of their range, though they may hibernate in Missouri where winters are colder.
Some species, such as the silver-haired bat, eastern red bat, hoary bat, and evening bat, are migratory, moving south in the fall and north in the spring, sometimes flying great distances and in rather large numbers. Some wander back and forth over multiple states during the fall. These migratory bats rarely enter caves. In some cases, as in the evening bat, some individuals may migrate in fall to warmer climates while others stay in Missouri and hibernate.
Many bat species show a high fidelity to their home caves, returning to the same hibernating sites year after year, and finding their way back even when transported 180 miles away from the cave in which they were trapped.
Control
Human Connections
Bats have been maligned as disease-causing nuisances. Bats infected with rabies have been found in Missouri, but their numbers are very low. Only about 3 percent of bats submitted for testing have tested positive for rabies. It is impossible to determine if a bat has rabies without laboratory tests, and rabies testing is lethal for the bat. For the safety of both humans and wildlife, it is best to avoid situations where a bite may occur. The potential for contracting rabies is slight, but handling bats (or any other wild mammal) is not recommended. Anyone who has been bitten by a bat should try to capture it, wash and disinfect the wound, and contact a physician or local health official immediately.
There is concern that humans may give North American bats COVID-19, but recent studies have shown that most of Missouri’s bats are not susceptible to COVID-19. However, people who are sick should not handle bats without a mask. As with other wild mammals, do not handle bats without proper rabies vaccinations and training.
Bats are important as predators of agricultural pests, as pollinators, and as seed dispersers, and their benefits far outweigh their potential for damage. Many people put up bat houses to attract insect-devouring bats to their neighborhoods.
Compared to bird watching, “mammal watching” isn’t really a “thing.” But bats are interesting to watch. It is fun to observe them fluttering silently among the trees and rooftops as the stars are coming out.
Ecosystem Connections
Bats are one of the few animals to regularly move in and out of caves. By eating insects outside of caves, then flying into caves and excreting the digestive remains, they bring organic nutrients into the cave ecosystem. Bat guano, and the decomposing remains of dead bats that fall to the cave floor, feed many small organisms that are then eaten by other forms of cave live.
Bats are also an important control on insect populations, and they are preyed upon by many kinds of animals, such as owls and snakes that wait for bats as they exit their roots in the evening.
Bat conservation is one of the main reasons why most caves are now closed to the public, at least seasonally. These closures not only help bats to survive and reproduce successfully, but also protect many other sensitive organisms in cave systems. Even before white-nose syndrome, a lot of the population declines for the Indiana and gray myotises were due to human disturbance of roost caves.
Protecting cave-dwelling bats also includes protecting their underground habitats from pollution. This improves the stability and quality of interconnected karst features such as groundwater, springs, sinkholes, and cave systems.
The predator-prey relationship between bats and moths has led moths to evolve many fascinating ways to avoid being captured by bats. Several types of moths, upon sensing the sonar clicks of bats, will immediately, reflexively, engage in erratic flight patterns, or produce sounds that can confuse or jam the bats’ echolocation abilities.
As the only mammals capable of true flight, bats are a unique and cherished life form on planet Earth.
