Friday, 28 July 2017

“No I’m not an ‘escort’”- and other awkward scenarios for bat surveyors.

Natterer's bat found during hibernation survey
It’s dark, damp and reeks of fox dung. I’m in a disused train tunnel in north London, tagging along to a survey for hibernating bats. As I inch along I stick close to the walls keeping an eye out for the little critters squeezed in-between the brick crevices. I need to be mindful of train tracks, loose rubble and syringes. Lots of used syringes. The tunnels have been sealed for a while now so, although I doubt I’ll be stumbling into whoever left these, it does bring to light a small yet unfortunate risk with bat surveying; you wouldn’t want to stop and chat with some of the people you might find. Never mind the tunnels and graveyards, but even walking through a park at night can turn dodgy, especially if you’re in a city. Bumping into the unsettling ‘types’ was at the back of my mind when I first started looking for bats around London, but little did it occur to me that I would be the ‘type’ to unsettle others. After all bat workers lurk in bushes with funny equipment in the middle of the night, what could possibly go wrong?

Common pipistrelle
There’s a park just around the corner from my home which has a great site for spotting bats. In a dark corner under an oak tree, when the weather is nice and warm, you can see bats swarming; effortlessly flitting between the gnarled branches chasing midges and flies. Armed with my heterodyne detector, I can pick up on their ultrasonic calls as they’re converted into audible sounds helping me detect the presence and species of bats nearby. When I arrive the detector is silent save for the background static hiss. All of the sudden a series of quiet pops crackle from the speaker, a bat’s in the area. The pops get louder turning into rhythmic wet slaps, must be a pipistrelle species. I tune through the frequencies finding the pitch where the slaps are deepest to help me discern what species I’m listening to. 45khz, it’s a common pipistrelle! In a matter of minutes the air is seething with bats while my detector emits a symphony of pop, squeak, smack and fart sounds as the pipistrelles acoustically feel their way through the air searching for insects to eat.

Tempting as it may be to stand there oohing and aahing at this mesmerising display I need to be aware of the other people in the park. Fortunately for me I’m standing next to the exit so I’ve got an easy way out if I don’t like the look of anyone approaching. Not so fortunate for the hapless jogger, there’s a man standing in the shadows just off the path right next to their exit point. It’s hard enough not to be confused for a nut in the daytime when justifying to people why you spend your nights looking for bats. Trying to do the same with a wary stranger in the park isn’t any easier. But it isn’t just late night joggers and dog walkers that I’m making anxious. A man pulls up in a car just outside the exit and waits with the engine running. I doubt it’s an uber, unless ‘tuned up with spoilers’ is now a selectable option. “He’s probably just picking up a mate” I’m thinking. His ‘mate’ turns up and they talk for less than a minute. Whats this? No hugs, no kisses? It’s starting to look more like a transaction now. What kind of a person conducts business from their car outside a park at night I wonder? At what must be the worst possible timing, my detector screeches and whistles as it picks up some feedback. The two men stop talking and turn to me. Now my gear is looking more like recording equipment or even a radio. For the police perhaps? I take my queue and leave before things get more awkward.

Bat surveyor or police informant, you be the judge
Surveying with a heterodyne needn’t be such a conspicuous display; a pair of headphones can cut out the noise while the detector is hidden in a pocket. However, other survey techniques require the use of less subtle hardware, like say a large antenna for radio-tracking. Remember the documentary clips of tranquillised lions and wolves being fitted with radio collars? Same principle applies except on a smaller scale. You catch your bat, glue a tracking device to their back and let them go. Equipped with your antennae you can map out their movements before the device falls off them, by which point you’ve got an idea as to where the bat flies and roosts; an invaluable insight for a researcher or conservationist. One such specialist goes by the name of Sam, a spectacled, soft-spoken bat ecologist who’s as comfortable researching in a library as he is trekking through the jungle. The kind of breed who could recount a scientific paper while changing a jeep tyre. One night our bat worker was driving around for a radio-tracking session. One hand on the wheel the other holding the antenna out the window. After having done a few circuits, he decides to take a little nap in the car. Not much time passes until he’s rudely awoken by an elderly man brandishing bills and documents at him through the wind screen. “I pay for my TV license!”. Sam’s groggy and confused at first until he realises the strange man is gesticulating partly at the antenna that’s been propped up on the passenger seat. The concerned resident thinks he’s under surveillance! Who’d of thought the BBC employed such drastic fee collection tactics?

Being confused for an authority figure is one thing, getting the authorities called on you is another. I had the pleasure of working with a researcher named Alison; a friendly, ebullient post-doc, not the kind of person you’d consider a delinquent. But like Sam, her equipment didn’t do her any favours. She was carrying out bat surveys in Birmingham using full spectrum bat recorders; the mac daddy of bat recording equipment. These are designed to be left in the field unattended where they continuously record at all frequencies providing tonnes of high quality data for later analysis. They’re typically incased in secure boxes to protect them from the weather, vandals and thieves (human and animal alike). The issue with setting these recorders up in an urban environment, thieves aside, is that you’re lurking around neighbourhoods hiding nondescript boxes around the place. Imagine what that would look like to someone peering out of their window. As if getting the police called wasn’t bad enough, she was once approached, mid-survey, by someone hoping to solicit a service. How hiking boots, rain macs and head torches could be interpreted as sex worker attire is beyond me, but we’ve all got our kinks I suppose.

by Charlie Hearst, former intern at BCT and active London Bat Group member (You can find him on Twitter @CharlieHearst, Facebook, Instagram and follow his blog too)

(To check if you have a local bat group near you visit this page . If you are interested in taking part in our National Bat Monitoring Programme surveys do visit this page)


  1. and then there is the hazard of outdoor "lovers" and their supporters along with some poor teen trying to have a quiet "smoke"...

  2. An I was asked if I was fishing in a private pond (of course, that's what radio tracking antennaes are made for!)