It’s an impossibly idyllic early summer evening on the Backs of Cambridge. A blackbird flutes as a man pressure-washes a table outside a hotel. Mating flies drift on the breeze, alongside a whiff of marijuana. A student lies flat on the riverbank, feet in the water.
Punting on the river Cam has stopped for the night but one boat slips into the gathering dusk: the Bat Punt Safari.
The charm of crashing into overhanging willow branches in the dark in pursuit of mostly feared nocturnal mammals is, unexpectedly, one of the hottest tickets in town. This Friday, the curtain lifts on the new bat-punting season, which has raised £36,000 for Cambridgeshire Wildlife Trust over recent summers.
“It’s the best bat experience in Britain,” says Iain Webb of the Wildlife Trust, who devised the concept and is approaching his 100th safari. “The fantastic thing about nature is that you don’t know what you’re going to see. You’re constantly surprised every time you go out.”
The most surprising thing Webb has seen on these nocturnal tours? A naked student swinging from a bridge. Our first strange sighting of the evening is a surfboard, adrift on the river, without any trace of an owner. “Surf’s down at the minute,” said Webb.
Scudamore’s Punts, which operates the safari, has taken bookings from all over the world, with one couple flying in from New Zealand for a second time to repeat their experience.
Almost as excited as the tourists is Samuel Harris, an artist and part-time punt “chauffeur”, who stands at the rear of the boat and expertly navigates fallen trees and the infamous “Dead Man’s Corner” where many a punter loses their quant (the pole) in a treacherously deep riverbed hole. It’s Harris’s first trip to look for bats. “I get a great view from where I am,” he says. “It’s a lovely thing to do on a Friday night.”
A tawny owl calls and Webb deciphers the “ak-ak-ak” of a juvenile heron, unseen in the riverside willows. Then, a flit of bat against the darkening sky.
It makes a wet slapping noise on the small bat detectors we hold up to pick up their echolocating sounds, which are too high for all but the youngest of human ears. Webb identifies it as soprano pipistrelle; soon we drift through a feeding pack of half a dozen beneath a busy road bridge.
Webb points out how their echolocation noises speed up – sounding like someone blowing a raspberry – as the bat closes in on its prey.
Each bat species sounds subtly different – the high-pitched wibbling of a lesser horseshoe bat is “like a 1960s alien,” according to Webb. We don’t hear that one but we’re soon picking up the “random hand-clapping” beat of a serotine bat, which looks noticeably bigger against the indigo sky.
Bats declined hugely in Britain during the 20th century with the loss of draughty roofs for roosting and the destruction of insect-rich wildflower meadows, but many species appear to be slowly increasing in number again this century.
Cambridge remains a bat hotspot, with a plethora of cavernous old college roofs to roost in and plenty of insects on the river Cam’s preserved water meadows.
Later, Webb takes out a high-powered lamp and sweeps it over the river. It illuminates a bat almost skimming the surface: Daubenton’s, also known as the water bat for its habit of seizing insects just above the water. With its pale belly and dipping flight, it looks like a nocturnal swallow.
What’s the appeal of bats? “We’re diurnal ground-based, slow-moving mammals and they are completely the opposite,” says Webb. “There’s so much mystery, and it’s amazing how much is still being learnt about bats.”