Originally published by the London Economic, January 10, 2018
It’s just finished lashing it down and a fantastic pink sunset is beginning to seep across the sky above Hampstead Heath. As I traipse soggily through the park, a series of bizarre blips and beeps suddenly erupts into the damp air. Forgetting about my wet feet for moment, I focus on the strange sound.
The tempo gathers pace, and the beeps start to get faster and louder. The noise swirls into a curiously rhythmic beat, building into a sound that’s almost funky. As quickly as it began, the otherworldly music moves towards its frenetic crescendo and abruptly stops. A short raspberry signals the end of the song. It’s not the sound of experimental electronica I’m hearing however, but the ultrasonic symphony of a bat on the hunt.
“That last noise is called the ‘feeding buzz’, which signals that the bat has found its prey,” explains our guide Ollie, a City of London parks officer and leader of tonight’s bat walk. The bat treating us to this natural dance party is a Noctule bat, the largest type in Britain and one of eight species recorded here on the Heath.
Despite their elusive nature, bats are absolutely everywhere. In fact, they make up a staggering one fifth of all the world’s mammals. Overall, there are 1,300 different species, the largest of which has a scarcely believable wingspan of 1.7 metres. Tonight though, we’re after just four, much smaller creatures: Pipistrelles, Daubenton’s, Brown long-eared bats, and Noctules.
“All UK bats hunt by ultrasound, which the human ear cannot detect,” Ollie tells us. To tackle that, we’ve been given bat detectors; little, black handheld devices that receive and re-tune the high pitched echolocation calls to a frequency that humans can hear.
Bat walks like this one have been taking place across north London since the late 90s, when Cindy Blaney, City of London Corporation Woodman at Highgate Wood, saw an opportunity to combine guided walks in London’s wild spaces with her passion for conservation and bats.