It’s dusk. The sun’s rays are slipping behind the Rad Cam as you stumble back into college. As the back gate shuts, something flits across your peripheral vision. You stop. Perhaps the Turf Tavern pint was stronger than you expected – but then you see it again, silhouetted against a purple sky. It’s a bat!
Last Trinity term, I was returning from an evening out when I spotted bats flying about in the quads of my college. To my delight, this was not just a one-off occurrence: the bats would almost always come out if the evening was warm and still. Since bats are protected by law, I can’t tell you the exact location where I saw them – if I did, I’d have to kill you (only joking, it was in Queens). My point is, though, bats are surprisingly common in Oxford, and relatively easy to spot, as they have little fear of humans and are active at student-friendly hours (Anyone fancy a 5am bird walk? I think not).
Bats get a bad rap. Associated with the supernatural in the past, they have been accused more recently of spreading disease, specifically coronaviruses. Any article extolling the virtues of bats should probably state that BATS DO NOT SPREAD COVID-19. The origins of the pandemic will probably never be known, but it seems that bat coronaviruses aren’t as closely related to COVID-19 as previously thought. In fact, bats are essential for healthy ecosystems. Bats pollinate banana, cocoa, mango, and more importantly agave, the raw material for tequila. They are the gardener’s friend, hoovering up agricultural pests in unholy quantities: a single pipistrelle bat needs to eat around 3,000 insects per night.
20% of all mammal species are bats, with 1,400+ species worldwide. These include the smallest mammal (the bumblebee bat, tipping the scales at a mere 2 grams) and the fastest (the Mexican free-tailed bat, flying along at 99mph). The UK has a less illustrious 18 species, although many argue this should be 17 since we are now down to our last greater mouse-eared bat. For twenty years, an elderly male hibernated all on his own in a railway tunnel in Sussex. This winter he seems to have vanished, but not before handing on the baton (ahaha) to a young female, who, it is hoped, will tempt sexy French bat-chelors (sorry) to cross the channel and set up a colony. In Oxfordshire, 14 species have been recorded, but only a few of those are likely to be seen in the city.
Here is a quick guide of the usual suspects and how to identify them:
– The Common Pipistrelle, creatively named Pipistrellus pipistrellus. The UK’s commonest bat by far, this is the one you’re most likely to spot. They emerge soon after sunset, and fly 2-10 metres above the ground, cavorting all over the place as they catch their insect prey. Despite being so familiar, the bat world received a shock in 1999, when it was discovered some so-called common pipistrelles were in fact Soprano Pipistrelles (Pipistrellus pygmaeus). The two species can only be told apart using a bat detector – common pipistrelles call at ~ 45khz, whereas the sopranos call at higher frequencies (55-80khz). There is also a third pipistrelle, Nathusius’s pipistrelle (Pipistrellus nathusii), but – before I get too carried away – this one is pretty rare. Nathusius’s pipistrelle is the UK’s only migratory bat, with individuals commuting from as far as Latvia.
– Daubenton’s bat (Myotis daubentonii). Oxford is famously watery, which is great for Daubenton’s bat, sometimes called the water bat. These bats have additional wing membranes stretching from their ankles to the tail, forming a pouch which they use to scoop prey from the surface of the water. Any bat flying low along a body of water is likely to be a Daubenton’s, although you’ll have to be quick as they zip along at 25kph.
– Brown long-eared bat (Plecotus auritus). These bats are known as whispering bats, as they echolocate extremely quietly. It’s thought this gives them greater aural sensitivity, allowing them to pinpoint insects sitting tight on the leaves of trees. Brown long-eared bats fly slow and close to foliage, often diving down into the undergrowth to catch stationary prey. These bats seem to take life at a leisurely pace, with some individuals reaching the grand old age of thirty. Not bad for an animal weighing less than a pencil.
– The Noctule. Revelling in the name Nyctalus noctula, the noctule is Britain’s largest bat. Although bigger isn’t always better, it’s also my favourite bat. These bad boys don’t bother with any fancy footwork, flying straight from A to B at 50kph. If you spot a large bat high up in the sky, flying in a straight line, it’s probably a noctule. Another way to identify noctules is by listening. Most bat species echolocate at a pitch beyond human hearing, however, the noctule calls at ~20khz, low enough for children, and adults with good hearing. (The noctule is the only bat whose echolocation we can hear, though sometimes humans can pick up on pipistrelle social calls. If what you’re hearing is a loud, high-pitched pulse, it’s a noctule).
It’s amazing to hear noctules and pipistrelles chatting away of an evening, but these simple wonders are becoming increasingly rare. Four of the UK’s bat species are at risk of national extinction, and many of the others have undergone catastrophic declines. The barbastelle bat, for example, has had a population crash of over 99%. There are many reasons behind these declines, not least use of pesticides killing off a lot of their insect prey, and development sealing up roosting sites in old buildings.
Fortunately, there are some simple things everyone can do to help our beleaguered bats. Rarer species are particularly affected by light pollution, so if you turn off outside lights between April and November (flight season) that will really help. If you have a cat, do not let it out at night between April and November. Cats do not eat bats, but, unfortunately, they do play with them, inflicting wounds to their delicate wing membranes. Needless to say, once a bat can no longer fly, it is effectively a furry kebab. However, if you do find a bat in trouble, Oxfordshire Bat Group has this page with advice about what to do.
I hope I have inspired you to think differently about bats and illuminated aspects of their mysterious lives. All you need to do now is spot them! Aside from the Back Quad of Queen’s, Port Meadow and the canal are some of the best places to see the four species mentioned above. Choose a warm, still, dry evening this Trinity, and you are almost guaranteed to see them. Happy hunting!