Mexican Free-Tailed Bat

## Description

The Mexican free-tailed bat or Brazilian free-tailed bat (Tadarida brasiliensis ) is a medium-sized bat native to the Americas, regarded as one of the most abundant mammals in North America. Its proclivity towards roosting in huge numbers at relatively few locations makes it vulnerable to habitat destruction in spite of its abundance. It has been claimed to have the fastest horizontal speed (as opposed to stoop diving speed) of any animal, reaching top ground speeds over 101 mph (162 km/h); its actual air speed has not been measured. The Texas Legislature designated the Mexican free-tailed bat the state mammal (flying) in 1995.

## Appearance

The Mexican free-tailed bat is a medium-sized bat native to the Americas and is regarded as one of the most abundant mammals in North America. It has been claimed to have the fastest horizontal speed (as opposed to stoop diving speed) of any animal, reaching top ground speeds over 100 mph (161 km/h).

## Distribution

Mexican free-tailed bat range from the southern half of the continental United States through most of Mexico, and through most of Central America into South America. They are also found in the Caribbean and are native to all of the Greater Antilles and 11 of the Lesser Antilles. Mexican free-tailed bats roost primarily in caves. However, they also roost in buildings of any type as long as they have access to openings and dark recesses in ceilings or walls. Before buildings, free-tailed bats in the Southeastern United States probably roosted in the hollows of trees such as red mangroves, black mangroves, white mangroves, and cypress.

## Behavior

Mexican free-tailed bats are social animals that live in large colonies. They are nocturnal foragers and begin feeding after dusk using echolocation for navigation and detecting prey. Their traveling calls are of a brief but constant frequency. These bats will fly 50 km (31 mi) in one night to reach foraging areas and they usually catch flying prey in flight. In warm weather free-tailed bats become more active and between June and September, they can be spotted in the late morning and afternoon. Mexican free-tailed bats are highly migratory and during winter most populations move to Mexico and Central America. Some bat populations do not migrate, but are residents and may make seasonal changes in roost sites.

## Diet

Mexican free-tailed bats are carnivores (insectivores). They eat moths, beetles, dragonflies, flies, true bugs, wasps, and ants.

## Reproduction

Mexican free-tailed bats are polygynandrous (promiscuous) breeders and both sexes mate with multiple partners. The mating season occurs once a year and typically lasts five weeks in the spring. During this time females aggregate into maternity roosts. The gestation period lasts 11-12 weeks, with only one young being born. A number of pups are left in "creches", while their mothers roost elsewhere. The female uses vocalizations and scent to identify her pup. She will nurse her young daily, and by 4-7 weeks old, the pup will be full-grown, fully weaned, and independent. Females become reproductively mature at about 9 months of age, while males are ready to breed when they are 2 years old.

## Population

### Threats

Though abundant and widespread, some local populations of the Mexican free-tailed bat are threatened by habitat destruction, human disturbance, mining in caves, pollution, and poisoning by pesticides.

### Number

According to IUCN, the Mexican free-tailed bat is locally common and widespread throughout its range but no overall population estimate is available. Currently, this species is classified as Least Concern (LC) on the IUCN Red List and its numbers today are stable.

## Fun Facts

The Mexican free-tailed bat is the official flying mammal of the state of Texas.

The tails of Mexican free-tailed bats are almost half their total length and stretch beyond the uropatagium (a structure that assists an animal in gliding or flight); this gives them the name "free-tailed" bats.

Mexican free-tailed bats possess deep wrinkles on the upper lip and have a Z-shaped upper third molar, which is used for grinding insects. The canines of these bats are larger in males than in females.

Mexican free-tailed bats fly the highest among bats, at altitudes around 3300 m.

Mexican free-tailed bats spend around 60% of their active time foraging while aerial, mostly hunting at heights of 6-15 m (20-49 ft).

The largest known colony of Mexican free-tailed bats is found at Bracken Cave, north of San Antonio, Texas, with nearly 20 million bats; the bats from this colony congregate in huge numbers at altitudes between 180 and 1,000 m (590 and 3,280 ft), and even as high as 3,000 m (9,800 ft).

Among bats that roost in great, concentrated numbers, Mexican free-tailed bats roosts produce large quantities of urine and guano; from 22 to 99 metric tons per cave, and over 18,700 metric tons are produced annually. The concentrated waste produces high levels of toxic ammonia in the air of a cave, however, these bats are able to withstand these high levels of ammonia and are able to filter it out before it reaches toxic levels in the blood. The bats are thought to swarm in spiraling motions within caves to ventilate ammonia and renew the air.

## References

https://animalia.bio/mexican-free-tailed-bat