Creatures of the night in Hertfordshire

With the sun setting earlier, the warm evenings of August are the perfect time to seek out night wildlife in your neighbourhood

LET’S start with what can be a challenging animal to spot – the bat. Being nocturnal, it’s usually too dark to see bats by the time they come out for the evening. Even if their movement can be seen in the half light, it’s almost impossible to see what they look like as they dive and jink in flight. So, how do you identify an animal that only becomes active after dark? Fortunately, all bats hunt by a form of radar know as echolocation – they emit high pitched sounds and listen for the sounds bouncing back off flying insects such as moths. Their sense of hearing is so well adapted that they can hone in, catch the insect and eat it as they fly. Most of the sounds that bats emit are far too high pitched for us to hear, so we need a bit of help in the form of an electronic ‘bat detector’. Put simply, this is a glorified transistor radio which, via a microphone, picks up the high pitched bat sounds, converts them to a frequency that we can hear and then transmits them through a loudspeaker. Depending on the bat species, what emerges from the speaker is a complex mix of clicks, rattles and pops, not that different from the sounds emitted from a bowl of rice crispies when the milk is added. However, keep listening and the sounds begin to make sense, with subtle rhythms and patterns. Bat detectors can be ‘tuned’, as each species of bat echolocates at a different frequency.To find out which bat you’re listening to on your detector, get hold of a copy of The Bat Detective, a field guide which comes with an excellent CD featuring 48 different bat calls. Or why not attend a bat identification event or night walk, where experts will help you sort out the Natterer’s from the Daubenton’s?

Other night flyers

Moths tend to come out at night, although not exclusively so – the amazingly beautiful six-spot burnet for example (pictured) is active by day and feeds mainly on bird’s-foot trefoil. Forget the image of dowdy brown flutterers eating your cardies – moths can be just as colourful as butterflies. It is very sad to say then that moth numbers have declined in the UK by around a third in the last 40 years. This is not only bad for moths, but for the bats that feed on moths too.To reveal the variety of different moth-life in your garden, try setting up a light trap. One of the easiest ways to attract moths is to spread out a white sheet and suspend a light above or in front of it. A normal light bulb should attract a few species but specialist bulbs (actinic light strips for example) are even better. Take care not to harm the moths if you are catching them in a pot to identify them and release them as soon as you can into the night.An eerie screech and ghostly white, silent flight – it must be the barn owl. These wonderful creatures hunt mainly at dusk and dawn and tend to comb open grassland for their prey, sweeping up and down. The more common tawny owl is the bird that makes the noise we know as ‘te-wit te-woo’. Interestingly this is not one but two separate calls and they are actually more like ‘kewick kewick’ and a long ‘hooo hu huhuhuhooo’. Tawny owls like wooded areas and tend to fly from tree to tree and are particularly nocturnal. The barn owl has suffered a huge decline in recent years, mainly due to changes in farming practices. Barn conversions have also resulted in the loss of traditional nesting sites.You can help these beautiful birds by becoming a sponsor – find out more on our website at: www.hertswildlifetrust.org.uk/shop/sponsorbarnowl

Night walk in Pishiobury Park, October 1

Join moth and bat experts who will help you spot these creatures of the night on a guided walk around Pishiobury Park near Sawbridgeworth. The walk starts at 6.30pm and lasts for approximately two hours.

To book, contact Jennifer Gilburt at Herts and Middlesex Wildlife Trust on01727 858901.

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