Bat Netting Lecture
(Watchable Wildlife Program Coordinator)
Arizona Game and Fish Department
Arizona is home to 28 species of bats, more than almost any other state. Bats are the only true flying mammals and are valuable human allies. Worldwide, they are primary predators of vast numbers of insect pests, saving farmers and foresters billions of dollars annually and helping to control insect-spread human diseases. For example, large colonies of Mexican free-tailed bats (Tadarida brasiliensis) eat hundreds of tons of moths each week, especially the moths that prey on cotton crops.
More Bat Information
Although bats play key roles in keeping insect populations in balance, they are North America’s most rapidly declining land mammals. Declines are often caused by human fear and persecution, and each of us can help by learning how to live with these animals.
Description and Habits
- Fist-sized or smaller, with short fur and thin wings, many have large ears
- Brown, gray, yellow, red, some with frost-tipped fur, spots or dark eye mask
- Similar eyesight to humans
- Many eat insects in flight and can eat more than 1,000 insects in an hour, including mosquitoes
- Some species drink nectar and can drain a hummingbird feeder overnight
- Use echolocation, emitting sound to locate solid objects
- Hang upside-down to rest in dark, secluded “roosts” during daytime; leave roost to forage for food at night and may temporarily roost to digest food and groom
- Some hibernate during winter (October through April), and some stay active year-round
- Most have one or two live young each year, usually between May and July
- Females nurse offspring and form maternity roosts that can contain hundreds or thousands of bats
Bats Under Bridges
- At least seven species of bats roost in crevices under some bridges in Arizona.
- There are several species of bats using this roost including pallid bats (Antrozus pallidus), cave myotis (Myotis velifer), and Yuma myotis (Myotis yumanensis). Canyon bats (Parastrellus hesperus) have also been found in this roost and other species, at least on occasion, are using the barn for roosting. Some species use this roost as a stopover during migration where they can rest for a short period before moving on. The majority of bats viewed on this camera are Myotis sp. and they are for the most part rather nondescript small bats with small to average sized ears and no facial adornments such as nose leafs. In July, a large group of over 100 Yuma myotis occupied the barn for a few weeks during their migration. Yuma myotis are one of the smaller myotis species weighing about as much as a nickel (0.16-0.25 oz.) and with a wingspan of between 9 and 10 inches. These bats prefer to forage near or over water and may be seen dipping and dodging over the many ponds on the Cluff Wildlife Area as they pursue moths, beetles and other insects.
- Bats are one of the most diverse and widespread groups of mammals on the planet today. They are found on every continent except Antarctica. One out of every four mammal species alive today is a bat. The Mexican free-tailed bat (Tadarida brasilensis), which occurs in Arizona, is also thought to be the most abundant mammal on Earth. Some colonies of this species number in the tens of millions. Bats belong to the order Chiroptera (meaning hand-wing) and are the only mammals to possess the powers of true flight. Though many mammals can glide considerable distances from one perch to another, only bats can truly fly. Worldwide bats are divided into two suborders. Megachiroptera is an Old World group which includes the world’s largest bats such as the flying foxes and other fruit bats. Microchiroptera is comprised of species found in both the Old and New World, some of which can be quite large but still far short of rivaling the size the largest Megachiroptera. For the most part Megachiroptera use their keen eyesight and sense of smell to navigate and find food while the Microchiroptera rely primarily on echolocation to interact with their environment. The largest species of bat in the world (flying fox) has a wingspan of nearly 6 feet while the smallest species (bumble bee or Kitty’s hog-nosed bat) has a wingspan of about 6 inches.
- Bats can be voracious. Some small species have been known to eat up to 12,000 mosquito-sized insects an hour. It is estimated that a single large colony of free-tailed bats in Texas eats about 200 tons of insects a night. Bats are also incredibly beneficial and not only an important natural control of insect populations, but also are the primary dispersers of seeds in tropical habitats and play a major role in re-establishing vegetation after logging or deforestation. Many bat species are long-lived, perhaps 30 years or more, and reproduce only once a year. If they lose their young they do not have another that year. Most species in Arizona have only one young a year.