There are about 900 types of bats worldwide. There are about 40 types of bats found north of Mexico.
Bats can be found in colonies; these are called colonial bats. Other bats do not live in colonies, and these are called solitary bats. Most bats found near humans are colonial bats.
Little brown bat (Myotis lucifugus)
The little brown bat is commonly found in and around buildings where there is an ample supply of insects nearby. The adults range from about 3 to 4 1/2 inches in length. The fur color is mid to dark brown and is glossy. The little brown bat has a wingspan of about 10 inches. These bats have a long lifespan and have been known to live for over 30 years. In summer, they roost in attics, behind house siding and in roof areas. They do hibernate in winter when the insect food supply is limited.
Big brown bat (Eptesicus fuscus)
The big brown bat is dark red/brown to dark brown and has a length as adults of 4 to 5 inches with a wingspan of 13 to 14 inches. The big brown bat is one of the most common bats found in and around buildings. This bat may share a roost with the little brown bat. Males might roost away from maternity colonies in buildings or near rocks and other crevices. Big brown bats have litters of one to two young, depending on the area of the country.
Mexican free-tailed bat (Tadarida brasiliensis)
The Mexican free-tailed bat prefers to roost near water sources such as ponds, rivers and lakes, where insect populations are adequate to support the feeding of the bats. The adult bat measures about 3 1/2 inches in length. These bats have been known to live for over 15 years.
The wingspan of this bat is about 1 foot, with some variation. The “free tail” part of the name stems from the fact that the tail is not included in the membrane, but is protruding freely. The adult color is dark brown to gray.
This bat has the largest colonies of any warm-blooded animal, with colonies found from Texas west to the Pacific and from Mexico north to about Idaho. The Mexican free-tailed bat migrates to overwinter in Mexico.
Pallid bat (Antrozous pallidus)
The pallid bat is another western species and is most known for its unique feeding and flying habits. This bat will fly close to the ground, almost appearing to hover, and will take most of its prey on the ground rather than in midair. Prey includes ground insects such as grasshoppers, beetles and scorpions.
Coloring of the pallid bat is much paler than most other species of bats, and this bat also has a lighter-colored underbelly. The body length of the adult is 3 1/2 to 5 1/2 inches. The wingspan is 14 to 15 1/2 inches.
Their colonies are small, rarely exceeding 100 bats.
Yuma myotis (Myotis yumanensis)
This bat is found mostly in the western states. The coloring of this bat is lighter than the little brown bat or the big brown bat. The underside is light to buff in color. The body length is 1 1/2 to 2 inches in length with a wingspan of just over 9 inches.
The colonies can be found near water sources. Most maternity colonies have up to 35 females that produce a single offspring.
Vampire bats are not found north of Mexico, but they have an interesting biology. These are the only mammals that feed exclusively on blood. Victims can be cows, horses and, in some cases, humans.
Vampire bats are found in Central America as well as tropical areas of Mexico. These bats land and approach the victim during the night while the host is sleeping. They crawl to the host and create a slight wound to feed on blood for up to 30 minutes. The blood loss does not cause a medical problem unless there are many wounds; however, the bites can become infected.
Likely due to the aforementioned habits of this bat, humans have developed their widespread fear of bats.
Baby vampire bats feed on the mother’s milk, as is the case with all mammals.
Fruit bats (Family Pteropodidae)
Fruit bats play an important role: they feed on fruits, helping disperse seeds and even pollen that helps with agricultural efforts in tropical areas. The fruits helped by these bats include banana, mango and durian, to name a few.
These bats are fair fliers, but some species have to crash land because they do not have the necessary skill to gracefully land.