24-May Bats at Dusk & Otters at Dawn: London’s Night-time Wild
Summary
As dusk falls over London’s parks, pipistrelles dart like shadows, noctules soar above treetops, and Daubenton’s bats skim rivers for mayflies—but the rarest of all, the ghostly greater horseshoe, lingers on the brink of vanishing. Meanwhile, along the city’s forgotten waterways, otters are making a cautious comeback. Why were they once hunted to the edge of extinction? And where can you spot their secret slides and spraints today?
Return on 24 May to uncover the night-time dramas of London’s bats and the quiet return of its most elusive swimmer.
Article
Bats
A warm, dry May evening, with plenty of moths in the air, is a good time to start looking for bats and our large parks and commons are good places to start e.g. Richmond Park, Wimbledon Common and Barnes Wetland Centre. Some of these early sightings may even be bats moving their family to new summer roosting sites. Pipistrelles, Noctules or Daubenton’s bats are the most likely to be seen.
Pipistrelles are the smallest and most common of the three. Although it is not easy to identify bats from their flight, the pipistrelle’s flight is the most erratic of the three. They start to fly just before sunset and often over gardens. It is their small size and scatter-brained flight that often gives them away. The Noctule is larger and has a much more determined flight, with occasional dives. They tend to fly higher above the trees, commencing at sunset. To have a chance of seeing a Daubenton’s bat it is best to be near water, where this medium-sized bat may well be hawking for insects. They fly fast, straight, and often low over the water, one of their favourite foods being emerging mayflies. Daubenton’s bats tend to commence flying a little later, typically around forty minutes after sunset.
On the edge of London there is also now a chance of seeing the secretive Brown long-eared bat. They also emerge later. It is their slower flight, with occasional hesitant hovering, that may possibly give them away. They also seem to have a preference for tall vegetation near old buildings.
Around Box Hill the Whiskered Leisler’s, Barbastelle, Natterer’s and Greater horseshoe bats are all waking up. Sadly, most sites in London hold fewer than twenty individuals. Gilbert White recorded ‘myriads’ of Noctules over the Thames.
Otters
Otter hunts were common around London a century ago. About six otter hounds would usually be used to nose out an otter. The otter would then dive into the water and be prevented from escaping by a hunting party armed with poles. The dogs were then encouraged to drag the poor creature to the bank, where it would be dispatched. At the time, anglers were hoping to exterminate the animal completely; whereas nowadays considerable efforts are being made to tempt them back. Recently artificial wooden and concrete holts are making some progress on this front. A dog otter may have a territory extending twenty-five miles along a river. Spraints (otter droppings) announcing their presence are now being found on the rivers Loddon, Wey and Blackwater. Other indicators of these nocturnal creatures are flattened areas of vegetation and muddy slides on riverbanks. Although they can give birth to their whips any month of the year generally it is this month that is most likely.
