North American Bats

Image of a bat in the attic flying

Approximately 25 percent of all mammal species is made up of over 1,000 species of bats, more than any other mammal group except rodents, and are found all over the world except in the most extreme desert and polar regions.

Some 40 species live in the United States and Canada, but most of them inhabit tropical forests where they sometimes outnumber all other mammals combined in the total number of species. Bats are the only mammal that has the ability to fly. They have wings instead of arms or hands. Similar to the human hand, the wings have a bone structure, and flaps of skin are between the bones. 1Go To Source nwf.org -“Night Friends- American Bats”

Bats have fur on their bodies, including sometimes their heads. However, their wings do not have fur. A range of colors, including red, tan, brown, and gray, are common for Bats. The ears of a bat are critical because bats use them for hunting for food. The ears tend to be prominent and noticeable, pointing up atop of the head. 2Go To Source nwf.org -“Bats”

Learn More: Nuisance Urbanized Animals 

Evolution Of The Bat

The evolution of bats remains a mysterious one, even with ever-emerging research and fossil records. Most scientists of evolution agree that bats must have evolved from mammals, but unfortunately, they can not find sufficient strong evidence from which typical ancestor bats split.

A long-standing argument in the scientific community is how the bat’s flight system developed over time. The debate was put to rest by the oldest fossilized bat, dated to be over 52 million years old. It turns out this animal could fly but could not utilize echolocation (location of objects by reflected sound).

It’s theorized that this creature was a day flyer until its species was compelled to become nocturnal to avoid new flying predators. 3Go To Source blogs.bu.edu -“Bats: A New Evolutionary Breed & A New Kind of Flight”

Bat Anatomy

Bats have webbing, which creates wings for them. Instead of any forelimbs, wings replace arms/legs. Usually, the bat’s limbs feature two sharp claws. They have a shorter claw that is comparable to a human thumb.

In the wings, there are bones that work like fingers. They are very versatile, which enables the bat to have a full range of movement easily.

Because of the bat’s anatomy, they are thought to be the only flying animal. Other animals only glide, including the flying squirrel.

The bat’s body is designed to use its senses to find prey, communicate, and fly around with its wings.

Bat Skull

The bats all have tiny teeth that are razor sharp. They can bite through the skin of fruits or prey easily. They also have a very long tongue for eating, drinking, and pollination that they use. When not using it, they can roll that tongue up around their rib cage too.

In their arteries, Bats have one-way valves to prevent blood from flowing backward. This is why, with blood rushing to their heads, they can hang upside down.

Bat eyes will differ depending on which species you encounter. Bats have a particular type of vision, so myths that bats are blind are false. Some species of bats have high-quality vision, and ultraviolet lighting can be detected. To compensate for vision pitfalls, they are able to depend on excellent hearing and smell.

Bat Claws

All bats have a thumb that sits along the wing’s leading edge. Usually, it has a powerful claw that is used to climb, handle food, and fight.

Bat thumbs vary considerably in size; there are generally longer and stronger thumbs for species whose feeding or roosting habits involve a lot of crawling.

The wing is supported by the rest of the digits (not including the thumb). The digits are equipped with sharp nails that assist in climbing, attacking prey, and roosting.

Bat Wings

Photo of a bat removed from a home

Bat wings usually run from the shoulder to the ankle, or in some cases, to the digits themselves. Except in a few instances where it occurs near the middle of the back, the wing membrane meets the body along the sides.

Bat biologists use several names to refer to different membrane parts. The propatagium runs from the wrist to the shoulder and is the wing’s leading edge. The area from the body to the 5th digit (wing) is included in the plagiopatagium. The dactylopatagium is called the membrane that spans digits 2-5.

In most bats, wing and tail membranes appear naked, but they may be covered with minute hairs upon close examination, and in some species have distinctive tufts and hair fringes. A few species have a thick layer of fur on their tail membranes and some parts of their wings. This fur is used to insulate the bat and to camouflage it. 4Go To Source animaldiversity.org -“Bat Wings and Tails”

Bat’s Heightened Senses

Just like humans, bats smell, hear, taste, feel, and see. The term “blind as a bat” is not really precise. To see in the daylight, Bats have perfectly good eyes. The problem is at night when they do most of their hunting!

Bats make fast, high-pitched squeaks called “ultrasounds” instead of relying on their sense of sight for night-time vision. For most people, these sounds are too high for them to hear.

The noises bounce back if these sounds hit something‚ÄĒsort of like you hear your echo in a mountain or a bathroom when you scream. The bat hears the echo and is able to tell the object where it is. This is called “echolocation” Not every bat species is capable of echolocation, but most can. 5Go To Source kidzone.ws -“Bat Senses”

Bat Size

In North America, adult bats range in weight from about 0.07 ounces with a wingspan of about 4 inches to those weighing over 2.2 pounds with a wingspan of almost 6 feet. Bats’ skeletal characteristics are similar to those of humans and most other mammals.

The bones of bats are typically small and delicate, unlike most birds that have hollow bones. To provide support for the wing membranes, the wings’ bones are longer/stronger than all of a bat’s bones. Between the elongated digits, a highly resilient double-membrane stretches and attaches to the body’s side and extends to the ankle.

Diet Of The Bat

Picture of a brown bat

The most important predators of night-flying insects are bats. There are at least 40 distinct kinds of bats that eat nothing but insects in the United States. A single small brown bat with a body no larger than the thumb of an adult human can eat 4 to 8 grams of insects every night. While this may not sound like much, it adds up.

By echolocation, bats locate every insect, then trap it with their wing or tail membranes and reach down to take the insect into their mouth. This action and the chase result in most individuals being familiar with the erratic flight when they observe bats feeding in the late evening or at night around lights.

There are many different things eaten by other species of bats, including fruit, nectar, and pollen. Bats are significant pollinators as they fly in search of food from plant to plant. Bats are the key pollinators of saguaro and organ pipe cacti in the southwestern deserts of North America. The agave plant, which is pollinated by bats, is made from tequila.

8 Most Common Insects Eaten By Bats

  1. Corn Earworm And Armyworm Moths
  2. June Beetles
  3. Green Stink Bugs
  4. Mosquitoes
  5. Crickets
  6. Cucumber Beetles
  7. Grasshoppers
  8. Sphynx

Bat Behavior

Bats hunt at night and roost during the day in trees, bat boxes, under eaves, and buildings. Bats will search for openings where they can gain access to structures through open spaces in roofs, attics, or walls because they are nocturnal.

Many bats migrate or hibernate during the winter, most actively in the spring and summer. These nocturnal mammals thrive in the dark due to their hearing abilities.

Reproduction Of Bats

There is a large variation in bats’ mating and rearing behaviors. During the fall, most bats mate, with egg fertilization delayed until the spring. The only mammals in which delayed fertilization occurs is the bat species.

A few species of bats wait to mate until spring. Most bats form maternity colonies consisting of adult women and their offspring beginning in April. In the warmer, lower elevations maternity colonies, they have been reported as sometimes starting as early as March already.

Maternity colonies also include non-reproducing yearling women who participate in rearing duties in some instances. 6Go To Source extension.arizona.edu -“Bats”

Bat Life Expectancy

Due to the wide amount of bat species, life expectancy can vary depending on the type of bat and its ecosystem.

Bats common to North America live up to six or seven years, although there was one 31-year-old little brown bat in the wild. Bats are one of the longest living smaller mammals. This can be attributed to their small list of predators and the ability to evade predators via flight.

Bat Communication

Bats are social mammals that communicate with each other and move around in the environment using a vocalization repertoire.

Bats emit a series of high-pitched sounds above 20,000 Hz (ultrasounds), beyond the human range of hearing, to detect obstacles and prey in their environment. As a bat flies and calls, to build up a sonic picture of its environment, it listens to the returning echoes of its calls. We call this process echolocation.

Individual species of bat echolocate within specific ranges of frequency that suit their types of environment and prey. Bats communicate by the kind of pitch that is being produced and the cadence of that pitch. 7Go To Source u.osu.edu -“Bat sounds”

Predators Of The Bat

Hawks and owls kill/eat bats regularly. During the day, snakes and predatory mammals such as weasels and raccoons climb into bat roosts and assault bats when they sleep.

Bats are even killed in some places by little birds that fly into bat caves and peck them to death. Then the birds drag the bats outside to eat them.

Bats are sometimes even eaten by fish that grab them as they try to catch insects when they skim over bodies of water.

Species

Bats belong to the biological order of Chiroptera. The bat families found in North America are Vespertilionidae, Molossidae, Mormoopidae and Phyllostomidae.

Vespertilionidae

Molossidae

Mormoopidae

Phyllostomidae

 

Sources:

1.The National Wildlife FederationTM and Bat Conservation International. (2020). Night Friends- American Bats. National Wildlife Federation. https://www.nwf.org/~/media/PDFs/Wildlife/batguide.ashx

2. Bats. (n.d.). National Wildlife Federation. Retrieved December 7, 2020, from https://www.nwf.org/Educational-Resources/Wildlife-Guide/Mammals/Bats

3. McCullough, J. (2012, September 26). Bats: A New Evolutionary Breed & A New Kind of Flight | Bio-Aerial Locomotion. Blog.Bu.Edu. http://blogs.bu.edu/bioaerial2012/2012/09/26/bats-a-new-evolutionary-breed-a-new-kind-of-flight-2/

4. Myers, P. (n.d.). ADW: Bat Wings and Tails. Animal Diversity. Retrieved December 7, 2020, from https://animaldiversity.org/collections/mammal_anatomy/bat_wings/

5. KidZone Bats. (n.d.). Kid Zone. Retrieved December 7, 2020, from https://www.kidzone.ws/ANIMALS/bats/facts8.htm

6. What do bats eat? (n.d.). USGS. Retrieved December 7, 2020, from https://www.usgs.gov/faqs/what-do-bats-eat

7. Bradley, R., & Rainsong, L. (2017, August 10). Bat sounds. Retrieved December 07, 2020, from https://u.osu.edu/biomuseum/2017/08/09/bat-sounds/