This is a list of bat species found in Iowa. The data has been copied (with permission) from
the Iowa DNR publication "A Guide to the Bats of Iowa" which can be
procured from the DNR. This publication was authored by Christyna M.
Laubach, John Bowles and Rene Laubach. The data is the property of
the Iowa DNR Wildlife Diversity Program.
I want to thank the Iowa DNR for publishing brochures like this
and allowing me to add this data to my website.
As members of the Order Chiroptera / bats comprise the second
largest mammalian order. Because they play interesting and often
unique roles in the natural world, bats come in many sizes and
colors, including red, yellow, and white, as well as various shades
of black and brown. Although all bats can see, some have much larger
eyes than others. Some have interesting facial adornments while
others are rather plain looking. A few have disproportionately large
ears and others rather small ones. There is even a variation in time
when bats feed. Although most bats are active after dark, many of
the large tropical fruit-eating bats feed during the daylight hours.
Feeding and Roosting
It is in the pursuit of night-flying insects that one of the most
interesting adaptive features of bats is best developed. Bats can
echolocate flying prey by emitting vocal sounds from the larynx and
mouth that are usually, but not exclusively, in the ultrasonic range
(up to 180 kHZ). These sound waves strike the prey and return as
echoes (sonar waves) that are funneled by the ears into a
specialized portion of the brain. So specialized is this mechanism
that bats can even compensate for rapidly changing distances and
angles as they approach their prey. Excellent summaries of how bats
use their sonar systems are provided by Fenton (1983) and Tuttle
Insect-feeding bats can often be seen foraging in twilight hours
along streams and forest edges or in town under street lights. The
foraging flight is erratic since bats dive after the insects,
catching them with their mouths, wing tips or tail membranes.
Insects too large to be handled in flight may be taken to a night
roost to be eaten. Since bats prefer juicier insect parts, legs and
wings usually are discarded.
When not foraging, bats utilize a variety of roosts. Some species
have alternate day and night retreats, the former being the more
secluded. Although Iowa's bats generally use natural roosts (e. g.,
loose tree bark, caves, tree cavities and foliage), some, especially
the big and little brown bats, also utilize buildings or other
man-made structures. In most North American species, males generally
do not roost with the females and young.
When evening approaches, roosting bats become restless and often are
noisy prior to departure. If their roosting shelter is large, the
bats may even fly about before emerging. Upon departure, they
frequently go first to water and drink by skimming the surface and
scooping water with their lower jaws. Bats may then feed for more
than two hours before returning to their roosts.
For many species, there is a second shorter feeding period just
before dawn; but by daylight, or shortly thereafter, all bats have
returned to their day retreats. Females usually modify this pattern
when their young are born since nursing mothers must spend more time
with their offspring.
When a bat lands in the roost, it banks slightly then catches hold
with its hind feet. This maneuver, which resembles a cartwheel, puts
it in the characteristic upside-down roosting position. While such a
position may aid in detection of predators, the primary advantage
seems to be in facilitating take-off. The bat simply releases its
hind feet, spreads its wings and becomes airborne. However, many
species can crawl with their wrists and hind feet along flat
surfaces to jump-off points for flight or can simply flip into the
air using both wings and legs.
Migration, Hibernation and Reproduction
Fall is a time for migration for most North American bats. During
this time, large numbers of bats may be flying in and around caves,
mines or similar cavernous structures. This phenomenon (swarming)
may be associated with reproduction since mating occurs in many
species during this time of year.
Although fall migration may commence as early as late July, by
August most bats are "moving," and may seek temporary refuge in or
on buildings enroute to their places of hibernation. At this time,
many bats store fat used in both migration and hibernation.
Additional fat deposition, however, may occur after arrival at the
wintering site (hibernaculum). In Iowa, four species-little brown
myotis, northern myotis, eastern pipistrelle, and big brown
bat-commonly hibernate in caves, and mines in eastern counties. A
fifth species (Indiana myotis) has been found hibernating in only
two places in Dubuque County. Other bats migrate southward. The only
species known to overwinter in buildings in Iowa is the big brown
bat. During hibernation, the bat's depressed body temperatures
reduce metabolism and fat utilization. If hibernating bats are
disturbed or aroused, their metabolism increases, depleting fat
reserves and diminishing their chances of surviving the winter.
While most mating activity occurs prior to hibernation, some takes
place during winter arousal periods when there are prolonged spells
of warm weather. In many bats, sperm cells are retained in the
female's uterus until spring when ovulation and fertilization
occurs. Gestation is about 50-60 days, with most young being born
between late May and late June, soon after females have returned to
their summer roosts. Colonial species form nurseries of 50 to 1,000
or more individuals in a variety of locations, including tree
hollows, under loose tree bark, and in buildings. Females of
solitary species roost in tree foliage.
While most bats produce one or two young per year, the red and hoary
bats regularly have three or four. When birthing, the female turns
right-side up as the young is born, receiving the baby in a pouch
formed by the tail membrane. Naked and with closed eyes, the young
bat resembles a miniature adult. In colonial species, the young
(normally left in the roost when the mothers forage) form small
clusters. Returning mothers recognize their own young by their own
distinct odor and/ or sound.
Young bats grow rapidly and are able to fly in about three weeks
when they are approximately three-fourths grown. In Iowa, this
usually is in late June to mid-July. After the young are weaned, the
nursery colony disperses. Hence, by late July or early August most
young of the year, having left the nurseries, frequent temporary
A variety of ectoparasites have been found in fur, in ears, and on
the wing and tail membranes of bats.
Several kinds of bed bugs, fleas, mites, chiggers and lice have been
taken from bats in Iowa, especially colonial species. Since such
ectoparasites are host specific in their feeding habits, there is no
danger of human infestation by bat parasites. For further
information about bat parasites, consult Fenton (1983) and Tuttle
For their small size, bats are surprisingly long lived.
This longevity, however, is a necessity for species survival given
the generally low reproductive rate of one or two young per year for
most species. While data are too scarce for age estimates of
non-colonial species (i. e., silver-haired, red and hoary bats), the
following longevity records exist for those that are colonial:
little brown myotis - 33 or 34 years in other states, northern
myotis -18.5, Indiana myotis - 13.8, eastern pipistrelle - 14.8, and
big brown bat -19.0. The oldest individual known from Iowa was a
pregnant female little brown myotis caught at the Manchester Fish
Hatchery 23 years after it had been banded (Bowles 1983)!
Anatomy, Evolution and Classification
Among the mammals, bats are the only true fliers; although other
animals, capable only of gliding, have common names that erroneously
infer flying ability (e.g., flying squirrel). The bat's wing is
built on the same general forelimb pattern as those of other
mammals: upper arm, forearm, wrist and hand with a thumb and four
fingers (Figure I, page 7). The fingers, however, are elongated and,
along with the wrist, serve to support and manipulate the thin
double-layered extension of wing skin, acting like umbrella ribs.
There is no flesh between the layers and only a small amount of
connective tissue with imbedded blood vessels and nerves. The thumb,
free of the membrane, is short with a sharply-hooked claw for
grooming and clinging. The hind toes are also clawed and aid in
Aside from minor modifications, the skeleton is similar to that of
other mammals. The typically mammalian skull has dental
modifications that reflect specific feeding habits (Figure 2, page
7). There is some fusion of vertebral joints for rigidity, the ribs
are flattened, and the breast bone (sternum) is keeled for
attachment of the enlarged wing muscles that give the downward pull.
The knees are directed outward and backward because the legs are
rotated to support the tail membrane. One of the ankle bones, the
calcaneus, bears a long spur (calcar) that projects toward the tail
and helps to support the tail membrane (Figure 3, page 7). The ears,
though thin and erect, are similar to those of most mammals except
for the presence of the well-developed tragus.
The tragus is a fleshy projection that arises from the inner base of
the external ear and appears to aid in directing incoming echoes to
the ear (Figure 4, page 7).
Most authorities believe that bats evolved from primitive
tree-dwelling mammals that fed primarily on insects. The exact
origin of bat flight, however, is difficult to trace since the
oldest known fossil skeletons from the middle Eocene geological
epoch (53-38 million years B.P.) are virtually identical to those of
today. Modem bats are cosmopolitan in distribution, being absent
only from the polar regions and some isolated volcanic islands. The
vast majority of bats, however, occur in the tropics.
Currently, two major groups of bats are recognized within the order
Chiroptera: Megachiroptera are the large fruit-eating bats of
Eurasia, Africa, and Indonesia and Microchioptera which vary in diet
and are nearly worldwide. It is in the latter group that
echolocation is best evolved, especially in the insect eaters. At
present, most authorities list 168 genera with 857 species of living
bats. These are placed in 18 families, of which only two (Vespertilionidae
and Molossidae) have been reported in Iowa.
Vespertilionidae is nearly world-wide in distribution with
representatives found from the tree line in Alaska and Canada
throughout most of the United States, Mexico and Central and South
America. Of these, the genus Myotis is the most widespread, having a
distribution roughly equivalent to that of the family.
Myotis lucifugus (LeConte), Little Brown Bat
Myotis sodalis (Miller and Allen), Indiana Bat
Myotis septentrionalis (Trouessart), Northern Myotis
Lasionycteris noctivagans (LeConte), Silver-haired Bat
Pipistrellus subflavus (F. Cuvier), Eastern Pipistrelle
Eptesicus fuscus (Beauvois), Big Brown Bat
Lasiurus borealis (Muller), Red Bat
Lasiurus cinereus (Palisot de Beauv), Hoary Bat
Nycticeius humeralis (Rafinesque), Evening Bat