Bats are extraordinary; they are the only flying mammals and make up 20% of mammals. Bats fall under the order of chiroptera which means hand- wing. Their wings are formed by elongated fingers. Bats have flexible bones in their wings which helps them maneuver while flying, they are able to avoid obstacles while flying up to 40 mph, the Mexican free-tailed bat (Tadarida brasiliensis) has been clocked going up to 80 mph while in a dive. Many bats migrate and hibernate during the winter. Bats are unusually long lived for their size, little brown bats (Myotis lucifugus) have been known to live past 31 years of age. Although, the actual average life-span of a bat is unknown. Bats are also slow at reproduction; they have been known to have one to four pups per year depending on the species.
Bats are split into two suborders, the megachiroptera (flying foxes/old world bats) and microchiroptera(small bats). The large flying fox (Pteropus vampyrus) are the largest of the bats with a wingspan up to 5.5 feet long. These species tend to be frugivorous, and use eyesight and olfactory senses to locate food as opposed to echolocation, that of which most bats are known for. The only flying fox that is capable of echolocation is the Egyptian fruit bat (Rousettus egyptiacus), that uses sonar to navigate caves. Frugivorous bats help forests by distributing seeds and some are pollinators. The bats that reside in North America are microchiroptera and feed primarily on insects. One bat can often eat up to 2,000 to 6,000 insects in one night.
Most microchiroptera bats use echolocation for hunting and orientation. Bat calls are made at such a high frequency that bat detectors are necessary to make them audible to humans. However, spotted bats (Euderma maculatum) have a low enough frequency call for humans to hear without the assistance of a bat detector.
Bats use echolocation by emitting sound waves. The sound waves bounce off an object, and the bat can decipher crucial information about the obstacle, surrounding area, or prey. The timing of the sound wave bouncing back will also tell the bat how far away the object is. A bat’s call is so loud that they have a muscular mechanism in their ear that allows the dampening of the call as to not harm their own sensitive hearing. Some species of prey, such as the tiger moth, have defenses to protect themselves against sonar. They send out their own clicks as the bat approaches, thus possibly throwing off the bat’s calls causing the bat to lose its target.
Bat detectors make the calls audible as well as records the frequencies of each call. By studying the frequency graph, it is possible to sometimes determine the genre of the bats recorded. This graph shows the feeding buzz for a big brown bat (Eptesicus fuscus). The points show each call the bat puts out. As the points get closer together the bat is calling more and more frequently because it is closing in on its prey. Thus at the end of the ‘hook’ where the curve ends is where the bat catches its prey. This call was recorded in Ravenna Park located in the University District of Seattle, Washington.
Bats are an important part of our ecosystems and they need to be protected along with the rest of the natural world.