Hi, I'm Rudi, i'm 8 years old and my favourite book is 'Tarka the Otter' by Henry Williamson. Its about the life of an otter named Tarka and British Wildlife. One night i was reading the book with my dad and i said that i wanted to see all the animals in the book, he said i should do it and call it the Tarka Challenge. My Tarka Challenge started on 1st January 2012. The book contains 89 birds, 54 land based animals, 120 plants and 56 aquatic organisms.

The rules are simple, i must either see each thing myself or photograph it using my trail camera. I will try and see each thing on my local patch (Ogmore River Catchment) but may need to look somewhere else in Britain.

Pipistrelle Bat

This is a quick film of me out with my bat detector. Each bat makes a sound using a different frequency. The bat detector tells you what frequency the sound is which helps you identify the bat, this bat was a Pipistrelle.

Off the list

Pipistrelle Bat (Pipistrellus pipistrellus)
This is the commonest bat in the uk and also the smallest. Its flight is quite jerky and it hunts quite close to the ground. Bats eat small flying insects. The Pipistrelle has recently been noticed as two different species (common pipistrelle and soprano pipistrelle). You can tell them apart using a bat detector. The frequency of a common pipistrelle is 45kHz and the frequency of a soprano pipistrelle is 55kHz. The bat in this film is a common pipistrelle. When we were on holiday in Scotland the bat flying around our house then was a soprano pipistrelle.


  1. Well captured Rudi. I bought a bat detector some years ago but the bats soon stopped visiting so I only managed one quick recording.

    1. Thanks John, hope your bats come back soon