What’s a common bat? A bat could be very common in a small area, but uncommon to nonexistent anywhere else. I have picked bats here that are common in a large part of the country. However, just because a bat is common, does not mean it is going to be easy to find. Remember that these are small night creatures that don’t make much noise that we can hear and tend to blend into the night.
Big brown bat: One of the most common bats found throughout the continental U.S. Fairly large for a U.S. bat with a length about 4.5 inches and a weight of a little over 1/2 an ounce. Usually dark brown in color. Roosts in trees, buildings and bridges. Eats a wide variety of flying insects, but especially seems to like beetles. Scientific name is Eptesicus fuscus.
Little brown myotis (little brown bat): At one time, this was the most common bat people experienced throughout most of the U.S. (except the South). Its population has been decimated in the Northeast by white nose syndrome. It hibernates in caves and would be large groups in the East that could be hundreds of thousands. This made them very susceptible to the disease. In the west, they do not hibernate in such large numbers and scientists hope that white nose syndrome does not challenge them. This is a small bat about 3.5 inches long and weighing 1/3 ounce. It eats lots of small insects, including mosquitoes. Often seen feeding over water. Scientific name is Myotis lucifugus.
Mexican free-tailed bat:
This bat lives in groups and is known for its spectacular colonies in Texas and the Southwest that hold millions of bats. It generally has much smaller colonies through its range of the southern half of the U.S. This very common bat is about 3.75 inches long with a weight of 2/5 ounce. This dark brown bat is fast and high-flying and feeds heavily on moths and beetles, including some serious crop pests. It roosts in caves, bridges, and buildings. Scientific name is Tadarida brasiliensis. You will find this also named Brazilian free-tailed bat because of the scientific name. While it ranges from North to South America, in the U.S., it migrates to Mexico, so Mexican free-tailed bat makes sense. It has also been called the guano bat because the large caves with millions of bats have a lot of guano and it was once “mined” for profit.
Tri-colored bat (used to be called Eastern pipistrelle): A very small bat living in the eastern U.S. It is has a length of about 3.25 inches and weighs around 1/4 ounce. A paler bat, its fur is typically yellow-brown to gray-brown. It hunts a variety of smaller insects over water and around the edges of trees. It’s weak, fluttery flight makes it look like a large butterfly. This bat roosts in caves, and in the summer, trees. It is rarely found in buildings. Scientific name is Perimyotis subflavus.
Canyon bat (used to be called Western pipistrelle): One of the most common bats in the Southwest, and it is so small that it is often mistaken for a large moth. This tiny bat is just under 3 inches long and weighs barely 1/8 ounce. It generally has light-colored fur and a black face and ears. Usually roosts in rock crevices. Eats just about any small insect it can catch, but especially swarming insects. Scientific name is Parastrellus hesperus.
Eastern red bat: This medium-sized bat is common in the Eastern half of the U.S. This bat can be 3.5-4.5 inches long with a weight of 1/3 – 3/5 ounce. This is a very attractive, heavily furred bat with reddish hair. It is a solitary bat that roosts in trees and eat a variety of insects, including larger ones such as crickets and cicadas. Scientific name is Lasiurus borealis.
This is one of the most wide-spread bats in the Americas, even with a variety found in Hawaii. It is a large bat that can be 5 inches long with a weight of a whole ounce! (That’s big for a U.S. bat.) It has brown and yellow fur that is tipped in white, giving the fur a frosted or hoary look. This is a heavily furred bat, too. It roosts alone in trees and eats many larger kinds of insects, especially moths. It has been known to kill and eat small bats, too. Scientific name is Lasiurus cinereus. The bat in the photo is held by a researcher who studies bats.
A very common bat from the Rockies west. A small bat with a length of 3.5 inches and a weight of 1/5 ounce. Light fur in desert areas, darker brown in Pacific Northwest, and always with very dark face and ears. Roost in hollow trees, caves, mines and buildings. Eats small insects from flies to moths. Scientific name is Myotis californicus.
Northern myotis: This bat is common through the Midwest to the Northeast and somewhat into the South. It is a smaller bat about 3.4 inches long and weighing only 1/4 ounce. This dark bat flies mainly in forests in search of its insect prey. It has long ears that help it even hear insects on leaves and branches, and will hover right up to them to pick them off. Northern myotis do not catch prey in the air. They roost in trees. Scientific name is Myotis septentrionalis.
This bat is striking for its pale color and very large ears. It is common through the deserts and other arid Southwest and California ecosystems. It is a large bat at about 4.5 inches long and up to an ounce in weight. It feeds by flying slowly and listening for the sounds of its prey moving across the ground or on tree leaves and branches, such as larger insects and other small critters like scorpions and centipedes. Pallid bats have been known to eat lizards and small rodents, too. They roost in crevices in rocks, buildings, bridges and even rock piles. Scientific name is Antrozous pallidus.
Seminole bat: This southern bat is often seen flying at night around street lights in the Southeast. It is a medium-sized bat a little under 4 inches in length and weighs about 1/2 ounce. It is one of the heavily furred bats like the red bat and has been confused with it. It has darker fur than the red bat (and is sometimes also called the mahagony bat). It eats many types of insects and seems to prefer insects that swarm near trees. It loves to roost alone in Spanish moss on the Southwestern side of a tree. Scientific name is Lasiurus seminolus.
Western red bat: This bat used to be considered just a variant of the Eastern red bat, but scientists have found enough difference to make it a separate species living in the West, common in California. It is solitary like the red bat and prefers to roost in cottonwood trees growing beside streams. It is about 4 inches long and weighs about 1/2 ounce. It has a red color similar to the red bat, but the dense fur is rusty red. It eats moths and other insects. Scientific name is Lasiurus blossevillii.