If the 28^th of August [updated date for 2021] isn’t already in your calendar, then it’s time to add a new yearly event as it’s a chance to celebrate and connect with bats and bat enthusiasts all over the world. People have gotten together on the last weekend of August since 1997 and if this is the first-time bats have ever been on your radar then you’re in for a treat. International Bat Weekend coincides with the peak of mating season for many of the 17 species of bats found in the UK which resulted in breath-taking swarms breathing life into dusk and dawn skies.

You might think the best way to take in this display would be to buy a bat detector, find a cave or some woodlands and try to tune into their mating call frequencies. If you have the time and money to do so, that’s great! But living in London means that there is so much nature right on our doorstep the only equipment you need is yourself, some transportation (your feet should do) and maybe a windbreaker to dampen the mild Autumn chill in the air whilst you head over to your local pond, canal or river. Bats need to stay hydrated just like us, so staking out a water body is the perfect place to spot a wide range of species.

What can you see and where?

Across London

The common pipistrelle (pictured above) is the smallest UK bat, with a wingspan of 20-23.5cm and weighing in at 4-6 grams (about the weight of a 2p coin). They fly quickly and erratically with many twists and turns. They can be found across Greater London in woodland, parks, along hedgerows and even gardens.

The soprano pipistrelle is similar in size to the common pipistrelle and has similar flight patterns. The easiest way to distinguish them is from the frequency of their echolocation calls (55-80kHz soprano and 45-70kHz). They can also be found across in gardens across Greater London but prefer wetland habitats such as riverbanks.

Noctules are one of the largest bats found in the UK weighing at least 3 times more than pipistrelles (18-40g) and have a wingspan between 32 and 40cm. Characterised by their sleek golden fur and broad brown ears, they fly quickly and direct with steep dives. They prefer roosting in trees, woodpecker or rot holes, but can be spotted in many central London parks such as Hyde Park, Regents Park, Hampstead Heath. They’ve also been seen along the Thames river in Teddington, Oxleas Wood in Greenwich and Berwick pond, Havering.

North and West London

Nathusius’s pipistrelle is a recent migrant to the UK and the rarest pipistrelle you’ll find in London. They are slightly larger than the common pipistrelles with a wingspan of 22.8-25cm and fly quickly and directly. They can be found around large lakes and woodland, with Richmond park being a great place to spot one.

Daubenton’s bat is medium-sized, weighing between 7 and 12 grams and have a wingspan of 24 to 27cm. Their flight is characterised by flying level and steadily approximately 10cm above the surface of water bodies. They were nicknamed ‘water bats’ as they usually hunt close to their water by using their feet as a spear or their tail membrane as a scoop for insects. If you’re exploring Gutteridge Wood, heading along the Grand Union Canal in Hillingdon is a great opportunity to catch this ‘water bat’ in action. They can also be found in Bushey Park and around Beech Hill Lake and Oak Hill Wood in Barnet.

Natterer’s bats (pictured below) are similar in size to Daubenton’s bats but distinguishable by the pinkish colouration of its limbs hence the nickname ‘red-armed bat’. They fly slowly but with agility as they have great manoeuvrability due to their broad wings. They have been spotted across Highgate Woods and can be seen roosting in trees and bat boxes across the site.

Central London

Noctules are one of the largest bats found in the UK weighing at least 3 times more than pipistrelles (18-40g) and have a wingspan between 32 and 40cm. Characterised by their sleek golden fur and broad brown ears, they fly quickly and direct with steep dives. They prefer roosting in trees, woodpecker or rot holes, but can be spotted in many central London parks such as Hyde Park, Regents Park, Hampstead Heath.

South London

Serotines (pictured below) are large bats, weighing in at 15-35g with a wingspan of 32-38cm, their ‘flapping’ flight appears leisurely and highly manoeuvrable with occasional short glides or steep descents. Their roosting preferences are more stereotypically batty as they’re often found in older buildings and houses with high gables. As newer buildings aren’t built with large bat habitats in mind, they are found in the outer boroughs of London such as Bromley, Havering and Sutton.

But why bats?

Bats have gotten a tonne of bad press over the past few millennia, from being symbolic of darkness, death and vampires in Europe (Castlevania anyone?), the land of dead, destruction and decay in Aztec mythology. Even as a young girl in Nigeria, I had heard the old folklore of bat’s nocturnal behaviour was a self-imposed punishment for tricking its bush-rat friend to turn itself into soup. Whilst we now understand better that these are myths which should be dispelled, bats continue to get a bad rap due to being disease carriers for some high-profile pathogens (thanks Ebola, Rabies, Nipah…) This is an incredibly damaging stereotype which ignores the fact that many animals that humans have co-evolved with can also carry many of the same pathogens including, cats, dogs, pigs and cows!

Globally, bats are incredible animals relied on for pollination, seed dispersal and even reforesting. Bat droppings (guano) are one of the richest fertilizers in the world, so when they eat fruit, digest it and then excrete the seeds away from the original tree, seed packages are delivered with ready-made fertilizer. The discovery of guano played a pivotal role in the development of intensive farming - guano was Texas’ largest mineral export before it got into oil! In the UK, they makeup nearly 1/3 of all mammal species and help keep the mosquito population at bay by being overnight pest controllers. Even the Department for the Environment, Food and Rural Affairs (DEFRA) recognises their importance as indicators of biodiversity and environmental health. Eight bat species have been included in the DEFRA’s list of ‘indicator species’ to monitor biodiversity loss. The long-term population trends of bats are used as they are top predators of nocturnal insects and are sensitive to land-use changes and urban development. Most bats are limited to having one pup per year, making it difficult for populations to recover quickly so they are extremely vulnerable to extinction. The most recent International Union for Conservation of Nature (IUCN) assessment of mammal species native to England found that 4/10 mammal classified as threatened with extinction were bats; greater mouse-eared bat, grey long-eared bat, serotine and barbastelle.

The unfortunate truth is that it is easier to blame an animal species for spillovers of disease into the human population than it is to critically analyse and evaluate our anthropogenic activities, such as habitat destruction and human encroachment, causing increased human-wildlife conflict. Humans and bats have shared dwellings for thousands of years after natural resource scarcities due to unsympathetic development and changes in land use. Artificial roosts such as houses, mines and barns are becoming essential for the survival of many bat species. However, even this is under threat due to demolitions, renovations, artificial lighting and a shift towards air-tight buildings with no eaves for roosting.

Bats and their roosts (even uninhabited) are protected by law due to a dramatic decrease in their numbers during the past century. All bat species are protected by the Wildlife & Countryside Act (1981) as amended, Countryside and Rights of Way Act (2000) and the Conservation of Habitats and Species Regulations (2010). This makes it illegal to deliberately or irresponsibly kill, harm, capture or disturb bats, obstruct access to bat roosts or damage/destroy bat roosts.

This legislation, charities, volunteers and enthusiasts have all played a hand in the beginning to stabilise UK bat populations. However, the challenges that bats face are complex and require sustained intervention from people of all walks of life, including you and me.

That’s an easy statement to make but what does it mean practically? Well, are all the biting insects out to get you? Let the bats be the pest management service and reduce pesticide use. Need to protect your timber against rot? Follow government advice and choose one of the many bat-safe treatment options. Looking to draught-proof your home? Save money on your heating bill and set up some bat boxes!  And if you’re still not sure what the big deal is about bats, then use International Bat Weekend is your chance to scope out some educational resources and open your up your mind and heart to our new batty friends.