More than 1,300 species of bats exist today around the world, making them the most diverse group of mammals. As far as scientists can tell from ____1_____ and DNA evidence, it appears that among _____2_____, the ability to fly has only evolved three times in all of history. Bats are the only mammals capable of true, powered flight. Simply put, they flap their wings to generate lift. A few other mammals can glide through the forest, but bats are true aerial acrobats. 

The Evolution of Bats

Research suggests that bats gradually evolved the ability to fly over millions of years. Genetic evidence from DNA hints at the likelihood of bats sharing a common ancestor with the _____3_____ mammals of today’s forests. This includes the flying squirrels that are known to glide from tree to tree. Bats around the world today even have a structure in their physical anatomy that appears to be left over from their ancient gliding days. The uropatagium is a thin membrane stretched between the hindlimbs. Modern gliding mammals use their hindlimbs to create more stability in flight, and it appears that bats do the same. Bats are the fastest mammals on Earth. _____4_____ free-tailed bats were observed flying over 100 miles per hour! Most, however, fly much slower. 

Scientists classify bats into a group called the _____5_____. The oldest fossils of bat-like mammals have been dated to roughly 52 million years ago. There are a few big distinctions between modern bats and those of over 50 million years ago. Most notable is the difference in _____6_____ anatomy. It appears that bats did not evolve echolocation until much later. With echolocation, bats send sound waves out into the environment. They then detect how long it takes the sound to bounce off of objects and return to their ears. Echolocation is an amazing way of figuring out how far away objects are, especially flying insect meals!

Food, Shelter and Behavior

Most bats are _____7_____, feasting on all kinds of flying insects. In fact, healthy bat populations can greatly reduce the mosquito population, doing humans a favor. Some bats have been observed eating _____8_____ mosquitoes per hour! Some, especially in tropical regions, are frugivorous or nectarivorous, eating fruit and nectar instead. 

Instead of migrating, some bats go into hibernation to save precious, limited energy stores. This strategy allows them to survive the winter when food isn’t available. Other species of bats migrate long distances every winter. In tropical regions, bats have plenty of insect prey throughout the year and will stay active in all seasons.

Bats use a diverse range of habitats throughout the year. During summer evenings, small insectivorous (insect-eating) bats look for food near open water, such as ponds or streams. Most bats rest during the day in tree cavities, caves, mines, bridges, and rock crevices. Some species of bats stay in these _____9_____ locations to hibernate over winter. Some species, such as the Mexican free-tailed bat, come together to raise young in the spring and summer in a maternity colony. Bracken Cave in Central _____10_____ is home to the largest known maternity colony, with up to 20 million bats at a time. 

Bats Under Threat

More than half of the bat species that live in the United States are in severe decline. The bats are disappearing, and scientists are racing to figure out how to address this problem. The biggest factor contributing to the decline is _____11______ syndrome. This causes a ____12_____ to infect the noses of bats, eventually making them very sick. Luckily, they’ve figured out a way to treat the bats with medicine to get rid of this horrible thing.

Bats are also losing habitat. The hollow trees and isolated caves they most often rely on have been disrupted by human activities in much of the world. Scientists, communities and governments are working together to find solutions that will protect the bats while also supporting local communities.