Walker’s Bats of the World

"This really is an offshoot from Walker’s Mammals of the World by an American publisher who had got every single mammal in the world photographed. The bats bit was so popular that it was published separately. It’s got a good, clear summary of every species of bat that we knew then in the world. A few have been discovered since it came out, but it lists all 18 families, broken down into their species – a very good insight into all of the world’s bats. It tells us what they look like, with numerous photographs and drawings and a general text on their ways of life with a simple thumbnail sketch. One trouble with bats is the lack of depth of knowledge we yet have of most species. As we speak, some taxonomist is splitting one bat species into two species, and other bat species, of course, is becoming extinct, so species numbers are always changing. Some of the species mentioned in Walker’s are now extinct. They do have a pretty rough time and are more prone to extinction than many other mammal groups. You get things like typhoons that sweep across an island and wipe out all the fruit that the fruit bats feed on. That’s just one environmental disaster that can cause a bat extinction. Bats are very mobile so they have, over millions of years, spread to all parts of the world apart from the two poles and some very high points like Everest. Most of the species are in the tropics because you have most of the food types, most of the fruit and the insects. The smaller the land mass, the fewer species you get. Mainland Europe has 30 or 40 bat species, the UK has 17, Ireland has eight or nine, so it gets fewer as it gets smaller. There are about 5,000 mammal species in the world and 1,100 of those are bats. The fruit bats, or flying foxes, that we know about from the old world tropics—Australia, Africa, South East Asia—are a big group with around 180 species. All the others are insect-eating bats (although some also eat fruit)."