Aug 23

International Bat Night is happening this weekend, an event that hopes to inspire people across Europe to understand more about how bats live and why they are so important to conserve. A series of presentations, exhibitions and bat walks are happening in more than 30 countries, including the UK – check out the bat walk at Harcourt Arboretum in Oxford this Thursday.

To join in the celebrations, we have delved into the ARKive collection to come up with some truly batty facts to get you in the mood for International Bat Night and to hopefully inspire you to take part in an event near you!

Batty Fact No. 1

Vampire bats use infrared sensors to detect veins on their warm-blooded prey.

Common vampire bat photo

Common vampire bat

In a study published in the journal Nature, researchers found that vampire bats have evolved specialised heat-sensitive nerve channels around the nose, allowing the bats to home in on “hot spots” on their prey, where the veins run close to the skin’s surface. In other animals, including humans, these nerve channels are used to detect heat that would be damaging to the body at temperatures above 43ºC. However, in the vampire bat the channels in the nose have evolved to activate at a much cooler 30ºC, allowing the bat to detect the body heat of its prey. Clever stuff!

Batty Fact No. 2

The ‘smallest bat in the world’ prize goes to Kitti’s hog-nosed bat!

Photo of Kitti's hog-nosed bat being held by researcher

Kitti's hog-nosed bat being held by researcher

Kitti’s hog-nosed bat is not only the smallest bat in the world, but also the smallest mammal in existence, weighing a maximum of just 2 grams! It is also the sole living species of the family Craseonycteridae, meaning that its extinction would not only be the loss of an incredibly unique species, but an entire branch of the evolutionary tree would vanish from our planet.

Batty Fact No. 3

Brazilian free-tailed bats form the largest warm-blooded colonies in the world.

Brazilian free-tailed bats emerging at sunset

Brazilian free-tailed bats emerging at sunset

The Brazilian free-tailed bat exhibits some spectacular behaviour, emerging to feed at dusk in huge columns of several million individuals. Their flapping wings create a sound equivalent to a white-water river and their numbers are great enough to be detected by airport and weather radars. Feeding for longer each night than any other bat species, it travels as far as 31 miles from roosts to feeding grounds. The Brazilian free-tailed bats of Texas are estimated to consume from 6,000 to 18,000 metric tons of insects each year, many of which are agricultural pests – so in actual fact, they are doing us a favour!

Batty Fact No.  4

Bat guano is used as a fertiliser!

Brazilian free-tailed bat photo

Despite its name, the largest and most well-known populations of the Brazilian free-tailed bat are found in Mexico and Texas, USA.

When large numbers of bats live together in single caves, such as the Brazilian free-tailed bat, there is a huge build up of guano or bat droppings. This nutrient-rich mixture was once commercially extracted from caves on a large scale, to be sold as fertiliser. In the early 1900s it was the largest mineral export from Texas after oil, and it continues to be sold commercially although to a lesser degree.

Batty Fact No. 5

There are probably more bat species than you think…

Hoary bat

The hoary bat is one of the most wide-ranging bat species in the Americas

Over 1,100 bat species are known in the world which is about one fifth of all mammal species. Bats are widely distributed across the globe, with only the Arctic, Antarctic and some Oceanic islands being without them! The biggest diversity of species is found in the tropics, with about a third of the world’s bat species inhabiting Central and South America.

Batty Fact No. 6

All British bats use ‘echolocation’ to find their prey!

Greater horseshoe bat hunting a moth

Greater horseshoe bat hunting a moth

The greater horseshoe bat is the larger of the two horseshoe bats found in Britain and can live for up to 30 years! They are so-named from the horseshoe shaped nose ‘leaf’, used as part of the bat’s echolocation system. Bats are not blind as was once popularly thought – they have good eyesight but rely on echolocation to navigate and to detect their insect prey. Echolocation allows bats to orient themselves at night; they emit bursts of sound that are of such high frequencies they are beyond the human range of hearing and are called ‘ultrasound’. They then listen to and interpret the echoes bounced back from objects, including prey, around them, allowing them to build up a ‘sound-picture’ of their surroundings.

Batty Fact No. 7

Female bats can recognise the individual call of their pup

Bicoloured leaf-nosed bat

Bicoloured leaf-nosed bat

The bicoloured leaf-nosed bat gives birth to one pup each year, which it must locate in the crowded roost after foraging trips. The mother does this by calling to her pup and listening for its reply. Once nearby, she uses pheromones to identify it. She will suckle it for some weeks before it learns to fly and forage alone.

Batty Fact No. 8

What is a megabat?

Lyle's flying fox with wings outstretched

Lyle's flying fox with wings outstretched

Megabats are in the family Pteropodidae and are often referred to as fruit bats. They have large eyes and often a long muzzle resembling a dog or fox. Unlike British bats, they do not use echolocation to find food, but rely on their vision and sense of smell to find fruits and flowers to feed on. An example of a megabat is Lyle’s flying fox which feeds mainly on ripe fruit and occasionally nectar, pollen and blossom. Its primary sense when foraging is vision and it has well developed teeth which are used to chew fruit while spitting out most of the seeds and pulp. Unlike other bat families, fruit bats do not hibernate. Instead, Lyle’s flying fox produces heat by shivering, which keeps its body temperature between 33 and 37 ºC.

Batty Fact No. 9

Bats have evolved to live in toxic caves!

Schreiber's long-fingered bat colony roosting

Schreiber's long-fingered bat colony roosting

Bat caves are widely known to contain noxious gases, but this is actually a result of carpet beetles (Dermestidae) that feed on bat guano and fallen bats. These beetles multiply so rapidly as a result of such a constant food supply that the whole floor of a cave may be ‘carpeted’ with them. They produce waste that combines with water vapour to make ammonium hydroxide which is poisonous to most animals. However, bats have adapted to this potent atmosphere by lowering their metabolic rate, which causes the level of carbon dioxide dissolved in their blood to rise, thus neutralising the ammonia.

Batty Fact No. 10

A deadly fungus is threatening bats in North America

Indiana bat

The Indiana bat is found in the Midwest and eastern United States

North America’s bats are dying in record numbers from white-nose syndrome, a deadly fungus which is spreading across the United States and into Canada. First identified in 2006, white-nose syndrome is a fatal disease which infects the skin of hibernating bats, turning their snout frosty white. It is unclear exactly how the disease kills the bats, but it is thought to affect their ability to hibernate, causing infected bats to use up their fat reserves. The disease has already killed over a million bats of at least six different species, including the Indiana bat, little brown myotis, gray myotis and the cave bat. Unfortunately scientists still know very little about this worrying disease, so we can only hope they start to find the answers soon!

Hopefully this blog has made you go batty about bats, so if you want to learn more and find out about bat events in the UK, take a look at the Bat Conservation Trust.  And if it’s a rainy day and you are feeling creative, have a go at making ARKive’s very own vampire bat mask!

Rebecca Sennett,  ARKive Media Researcher