Bat

Bats, belonging to the order Chiroptera, are the only mammals that can fly. Capable of sustained flight, bats flap their long spread-out digits covered with a thin membranous structure (patagium) for flying. They are typically more maneuverable than birds, and this ability, combined with their capability to navigate using an acoustic orientation method, has made them a highly populous order.

Physical Description and Appearance

Size: Their size varies depending on the species. Kitti’s hog-nosed bat is the smallest bat species with a length of 1.14-1.34 in (29-34 mm) and a wingspan of 5.91 in (15 cm). The golden-crowned flying fox is one of the largest bats with a forearm length of 8.5 in (215 mm) and a wingspan of 4.9-5.6 ft (1.5-1.7 m).

Weight: The smallest Kitti’s hog-nosed bat weighs about 0.07-0.09 oz (2-2.6 g) while the giant golden-crowned flying fox has an average weight of 4 lb (1.6 kg).

Color: They are usually black or brown, but may have orange, white, red, or gray coloration. Certain types like the spotted bats possess white facial markings.

Head: The shape of their head varies by species with the megabats having larger eye sockets, smaller ears, and longer snouts, giving them a dog-like appearance. Microbat species like vampire bats possess reduced snouts for accommodating large canines and incisors.

Dentition: Insect-eating bats possess 38 teeth, while blood-sucking vampire bats have 20. Bats feeding on hard-shelled insects are characterized by longer canines and robust lower jaws. Nectar-feeding bats have long canines and reduced cheek-teeth, while fruit-eating bats have cheek-teeth cusps adapted for crushing.

Wings: Bats have much thinner wings, consisting of more bones as compared to the wings of birds. The wing surface has touch-sensitive receptors, while the patagium or wing membrane contains elastic fibers, nerves, blood vessels, connective tissues, and muscles.

Distribution

Aside from the Arctic, the Antarctic, and some isolated oceanic islands, bats are distributed throughout the world, being abundant in the tropics. About 45 bat species are found in the US, while approximately 100 species exist in West Africa.

What kind of Habitats do Bats live in

Bats can live in diverse habitats depending on the season, ranging from deserts to mountains and seasides. They need suitable roosts, which are found in crevices, foliage, hollows, and human-made structures. Megabats typically roost in trees.

How long do they live

In the wild, the average lifespan of bats is less than 20 years. Six species, including the Indian flying fox, greater horseshoe bat, lesser mouse-eared bat, Brandt’s bat, little brown bat, and brown long-eared bat, have been found to live for more than 30 years in the wild. In 2006, scientists found a tiny bat in Siberia, which was documented to be the longest-living, having survived for 41 years.

What do they eat

Most microbats are insectivores and feed on flies, mosquitoes, moths, beetles, crickets, grasshoppers, bees, termites, wasps, caddisflies, and mayflies. Megabats are usually frugivores that eat fruits, pollens, and nectar. Insectivorous bats consume more than 120% of their weight, whereas frugivorous bats eat over two times their body weight. The large amounts of food consumed make up for the energy lost through a flight.

Some bat species, such as the fringe-lipped bat hunts frogs, greater noctule bat feeds upon birds, and greater bulldog bat eats fish. Several species like the common hairy-legged and white-winged vampire bats feed on the blood of mammals and birds.

Behavior

• Microbats are generally nocturnal mammals, while most megabats are diurnal or crepuscular.
• Bats use their larynx for producing ultrasonic sounds, emitting through the mouth and occasionally the nose, thereby creating echoes. The outgoing pulse is compared with the returning echoes to create detailed images of the surroundings, allowing them to detect and identify their prey.
• In temperate regions, some microbat species migrate several hundred kilometers to their winter hibernation dens. Others pass into a state of decreased activity (torpor) during the winter months. Some bats retreat to caves where they hibernate for up to six months.
• Some species like the Mexican free-tailed bats live in colonies, while others such as the silver-haired bats lead a solitary life.
• They emit low-frequency calls for attracting mates and finding roost partners to defend resources.
• When not flying, they roost by hanging upside down from the feet. Most bats are capable of crawling awkwardly on the ground.

• Bats have a better ability to conduct heat than other mammals. Their wings consist of blood vessels that loose heat when extended. For this reason, they wrap the wings around their bodies at rest, trapping a layer of air for insulation.

Adaptations

• Their wing membranes are so thin and delicate that they help them to maneuver accurately and fly with less drag and more lift.
• The leading edges of the wings of pollen- and nectar-eating bats are so sharp that they create vortices, providing lift when flying.
• They have ankle joints that can be bent, allowing the trailing edge of their wings to curve downwards, thereby permitting them to clamber up and hang on trees. Bats also have tendons for locking their feet when roosting.
• Bats have a specialized respiratory system for coping with the demands of their energetically taxing flight, which requires a continuous supply of oxygen.
• Their ears are sensitive to the slightest of noises made by moths, tymbalate insects, and ground-dwelling centipedes and earwigs. The ridges located on the inner surface of their ears help them focus on echolocation signals and listen for other sounds made by the prey.
• Species like tube-lipped nectar bats have long, extensible tongues that are covered with fine bristles, helping them to feed on the nectar of flowering plants.

Reproduction and Mating

Bats may have polygynous (males have multiple female partners), monogamous (males have one mate at a time), and promiscuous (both males and females have multiple partners) mating systems depending on the species. Pipistrelle, vampire, and noctule bats are polygynous, while the little brown and Mexican free-tailed bats are promiscuous, and the spectral and yellow-winged bats are monogamous.

In temperate regions, bats mate during late summer or early autumn, while tropical bats copulate in the dry season. To prevent other males from mating, males leave behind a vaginal plug after copulation. Males of hibernating species mate with females in a dormant state.

Females of some bat species exhibit delayed fertilization, meaning the sperm is deposited in their reproductive tract, and fertilization takes place in spring several months after mating. Other species have delayed implantation, which means that the egg remains free in the mother’s reproductive tract, and the birth of young is delayed until conditions become favorable to care for the offspring.

Temperate-living bats in the northern and southern hemispheres give birth in May-June and November-December, respectively, while tropical species produce their offspring at the start of the rainy season. Females usually give birth to one offspring per litter. The pup weighs about 40 percent of its mother’s weight at birth. Young bats are weaned in about 80 days.

Conservation

In countries across Asia, Africa, and the Pacific, bats are eaten or hunted for food. Pressure damage caused by wind turbines also kills bats. Organizations like Bat Conservation International strive towards increasing awareness regarding the ecological roles played and the threats faced by bats. In the UK, the Wildlife and Countryside Acts protect all bat species, which means harming them in any way is a punishable offense. The Wildlife Protection Ordinance 1998 has also been implemented in Sarawak, Malaysia, to protect all bats from being hunted or eaten.

Bat-FAQs

1. Are bats blind?

Although no bats are blind, most microbat species have small and poorly-developed eyes, leading to poor clarity. They can detect low levels of light, while some microbats can even detect UV light. Megabats, on the other hand, have good eyesight that is adapted to daylight and night visions.

2. Do bats hibernate?

Some species, including Indiana bat, eastern red bat, silver-haired bat, and little brown bat hibernate in places like mines, caves, and rock crevices with ideal humidity and temperature.

3. Are bats rodents?

No. Bats are not even related to rodents.

4. Are bats dangerous?

Some bats can be harmful to humans since they may carry many infectious bacteria and viruses, including rabies, Nipah, Ebola, and coronaviruses.

5. Do bats lay eggs?

No

6. What is a baby bat called?

A pup

7. What is a group of bats called?

A colony

8. What predators may eat bats?

Birds of prey like hawks, owls, and falcons, alongside terrestrial predators such as cats and snakes, may hunt and feed on bats.

Interesting Facts

• Nectar-feeding bats act as pollinators, and more than 500 flowering plants and fruit trees depend on bat pollination for the dispersal of pollens and seeds.
• Microbats use magnetoreception, the sensitivity to the Earth’s magnetic field, for differentiating north from south. It is particularly useful in long-distance travel.
• In European cultures, bats symbolize darkness, witchcraft, death, and evil, while the Native Americans like the Cherokee, Apache, and Creek consider the bat as a trickster spirit.
• Insectivorous bats are helpful to farmers since they lessen the population of agricultural pests by reducing the use of pesticides.
• Bat dung or guano, being rich in nitrogen, potassium, and phosphate, serves as an effective fertilizer.