Stand outside on a warm May evening about twenty minutes after sunset. Give your eyes a moment. Look up.
There it is. A small, dark shape moving with extraordinary speed and complete unpredictability — twisting, diving, reversing — navigating the air in ways that feel impossible. That is a bat. Almost certainly a common pipistrelle. And it is eating insects in quantities that would astonish you if you knew the number.
May is the best month to watch bats in the UK. The evenings are long enough and warm enough to make standing outside feel like a pleasure rather than an endurance exercise. The insect population has woken up properly, which means the bats are out and active and not difficult to find. And if you've never really paid attention to bats before, this is the month that will change that.
"There are 18 species of bat in the UK. That's almost a quarter of all our mammal species. Most people couldn't name three of them."
Why May is the right month
UK bats are active from roughly April to November, hibernating through the colder months when insects are scarce. May marks the beginning of their most active period. Females are forming maternity colonies — gathering in groups to give birth and raise young. Males are actively feeding to build condition after winter. Insects are abundant. The evenings are getting longer by the day.
The other reason May works particularly well is the light. Earlier in spring the evenings are shorter and bats emerge later in darkness, making them harder to follow. By May, sunset is around 9pm and civil twilight extends well past that. You can watch bats emerge in the fading light, which makes following their flight considerably easier than trying to observe them against a black sky.
The five species you're most likely to see
How to actually watch bats
You need three things. A warm evening. A location with some combination of water, trees or hedgerows. And patience measured in minutes rather than hours.
The Daubenton's bat hunts insects directly from the water surface — one of the most remarkable flight behaviours in British wildlife.
Pipistrelles are the easiest starting point. Find a garden, park or hedgerow. Position yourself somewhere with a clear view of the sky, ideally near trees or a hedge. Wait twenty minutes after sunset. They will come to you.
For Daubenton's bats, find any body of still or slow-moving freshwater — a canal, a river, a lake, a reservoir, a millpond. Stand on a bridge or at the bank. Watch the water surface rather than the sky. You are looking for something low and fast, flying within centimetres of the water. The white belly flash will confirm it.
For the noctule, go somewhere open — a park, common, or field with mature trees nearby. Look high. If something is flying above the tree canopy before dark, moving fast in a relatively straight line with occasional steep dives, that's your noctule.
- Timing matters. Emerge twenty minutes after sunset for pipistrelles, later for brown long-eared bats. The noctule sometimes appears before dark.
- Water is your best bet. More than any other habitat, still freshwater concentrates insect activity and the bats that follow it.
- A bat detector transforms the experience. Around £20 online, it converts ultrasonic echolocation calls into audible clicks. Each species has a distinct call. This is not a promotion. It is just excellent.
- Stand still. Moving around disturbs the bats' foraging patterns. Find a spot with a clear view and stay there for at least fifteen minutes.
- All bats and their roosts are legally protected in the UK. Look, listen, enjoy. Do not disturb roosts or handle bats.
The inconvenient truth about bat numbers
British bat populations suffered catastrophic declines during the 20th century. Pesticide use decimated insect populations, which cascaded immediately into bat populations. Roost sites disappeared as old buildings were renovated, barns converted, and ancient trees removed. By the time anyone was paying systematic attention, several species had lost the majority of their population.
The picture is better now than it was. Legal protection since 1981 has helped. The Bat Conservation Trust has grown a national network of local bat groups who monitor populations, respond to roost disturbance, and run events for the public. Some species, particularly the common pipistrelle, appear to be recovering.
But the gains are fragile. Light pollution is an increasing problem — many bat species avoid artificially lit areas, which fragments their habitat. Modern buildings are better insulated and offer fewer roost opportunities than older stock. Climate change is shifting insect populations in ways that are not yet fully understood.
"A single common pipistrelle eats up to 3,000 insects in a night. A maternity colony of 200 bats eats roughly 600,000 insects every night of the summer. They are the most effective pest control service in Britain and they do it for free."
What you can actually do
The most useful thing most people can do is make their garden more bat-friendly. This is not complicated.
Plant night-scented flowers — honeysuckle, evening primrose, jasmine. These attract night-flying moths and other insects, which attract bats. Let a patch of grass grow long. Leave a log pile in a corner. Keep a section of hedge rather than a fence — hedges provide navigation routes for bats moving between feeding areas.
If you have the means, install a bat box on a south or south-east facing wall or tree, at least four metres from the ground. Pipistrelles will sometimes use them. It takes a season or two, but they will find it.
Keep outdoor lighting minimal, and where you have it, direct it downward rather than upward into the sky. Bats navigate partly by the contrast between lit and unlit areas. Flood-lighting an entire garden effectively destroys it as bat habitat.
A bat box installed on a south-facing wall or tree gives pipistrelles a roost alternative as old buildings are sealed up. (This image was taken from the RHS. To make sure they don't sue us, here's a link to buy the box)
If you find a bat on the ground — injured, exhausted, or simply a young bat that has left the roost too soon — do not pick it up with your bare hands. Call the Bat Conservation Trust's National Bat Helpline on 0345 1300 228. They will advise you.
The best places to watch bats in the UK in May
You do not need to travel far. Bats are everywhere. But if you want to find high concentrations and a range of species, certain habitats and locations are particularly good.
Any canal towpath. Canals are linear bat motorways. The water concentrates insects and the towpath gives you a clear sightline. Daubenton's bats are almost guaranteed at any decent stretch of canal at dusk. Canal and River Trust towpaths are free to walk and accessible across the UK.
Ancient parkland. Old trees with cavities, grassland with high insect diversity, minimal light pollution. Noctules roost in tree cavities. Brown long-eared bats hunt in the canopy. Look for pipistrelles around the wood edges.
The coast. Pipistrelles forage over coastal grassland and cliff tops where insect populations can be dense. Dorset coast, Norfolk coast, the Welsh cliffs — all good on warm May evenings.
Your garden, if you have one. Seriously. If you have trees, hedges or any water feature, stand outside at dusk for fifteen minutes. You may already share your space with bats and simply not know it.
The bat detector question
We've mentioned this once already and we will mention it again because it genuinely changes the experience.
A heterodyne bat detector takes ultrasonic echolocation calls — which operate at frequencies between 20 and 120 kHz, well above human hearing — and converts them into audible clicks and chirps. Each species has a characteristic call pattern. The common pipistrelle calls at around 45 kHz and sounds like a rapid ticking. The soprano pipistrelle calls at 55 kHz, slightly higher. The noctule produces a slow, loud chip at around 25 kHz that some adults can hear unaided on quiet nights. This might do your head in reading this, but we're assured it's great fun listening.
A basic detector costs around £20 to £30 online. It is not a gimmick. It will tell you which species are around you, how many there are, and where they are going. It is the closest thing to a superpower that costs less than a round of drinks.
The Bat Conservation Trust has a list of recommended detectors on their website at bats.org.uk.
The Quieter Field Notes go out on the first of every month. Each edition covers what's worth noticing outside that month — migratory birds, things to forage, astronomical events, the particular kind of quiet you only find in a specific season. If this was useful, the newsletter is better. Sign up at quieter.life.