As a wildlife veterinarian, I often get asked about bats. I like bats, and I am always eager to talk about how interesting they are. Unfortunately the question is often not about biology but instead “what should I do about the ones in my roof?”.
With some unique talents and remarkable sex lives, bats are actually one of the most interesting, diverse and misunderstood groups of animals. Contrary to popular belief, they are beautiful creatures. Not necessarily in the cuddly, human-like sense – although some fruit bats with doey brown eyes and button noses could be considered so – but they are beautifully designed.
This couldn’t be illustrated better than by the discovery of the oldest known complete bat fossil, more than 53 million-years-old yet with a similar wing design to those flying around today. To put it in perspective, 50m years ago our ancestors were still swinging from the trees and would certainly not be recognised as human. But even then bats already had the combination of thin, long forearms and fingers covered by an extremely thin, strong membrane, which allowed them to master the art of powered, agile flight.
Soon afterwards, fossils record another game-changing adaptation in the evolution of most bats, and that is the ability to accurately locate prey using sound (what we call echolocation). These two adaptations early in their history gave bats an evolutionary edge compared to some other mammals, and allowed them to diversify into almost all habitats, on every continent except Antarctica.
There are now more than 1,300 different species, divided among 26 different families (compared to fewer than 500 primate species). Indonesia alone has 219 different bat species.
It is not just a quantity though – the variety is astonishing. The thumb-sized bumblebee bat of Thailand is the smallest species, weighing just two grammes. And like other insectivorous bats, it can eat its own body weight in insects every night. At the other end of the scale, some large flying foxes have wingspans of well over a metre and, having lost the ability to echolocate, eat fruit and nectar.
Everyone knows that some bats feed on blood, but despite the “vampire” myth, only three species actually feed on blood. And these haematophagous bats are only found in parts of South America. They also definitely don’t get tangled in your hair. Bats are far too good at flying.
If thus far I haven’t persuaded you to like bats, you must admit that they are useful. Bats defecate while regularly flying very long distances (up to 350km in one night), making them extremely effective at dispersing seeds. Add to that the fact that some fruit bats live in colonies up to 1m strong, and you can start to imagine their impact. So much so, they have been proven key in reforestation.
Another unappreciated and major role is as pest controllers. The sheer volume of insects that some bats species can eat makes them very effective at suppressing pest insects. Bats reduce the nuisance and disease threat of mosquitoes, and it has been estimated they save the US economy at least $3.7 billion every year through increased crop productivity and reduction of pesticide usage.
Despite their ancient design, they show some remarkable talents. One of these is shared only by several select animals. Bats are vocal learners – able to learn and then imitate sounds even in adulthood. This is likely important for the development of the complex social organisation seen in many bat species. Most surprising of all is the recent revelation that they are also members of an even more exclusive and less salubrious club: animals known to partake in fellatio during copulation.
Bats have had some bad press recently due to their association with infectious diseases, from rabies to Ebola. And they appear able to tolerate some viruses fatal to other species. If anything, that illustrates again why they should be respected, especially as various bat species are also endangered and therefore protected by law in many regions.
So my response to those interested in what to do about the bats in their roof? Leave them alone.