The 'Let's go Batty' event which took place on 9th September 2006 showed that four varieties of bat are living in the Dene. The event was held by the rangers and everyone met up at Millfield House. Participants learned about the types of bats living in the U.K. and their habits and habitats. A 'bat detector' was used and this picked up the different echolocation frequencies used by the bats. This identified a colony of Noctules living by the picnic area. These are the largest of U.K. bats. Then some Daubenton's were discovered living near the bridge. Next, the bat detector picked up a group of Pipistrelles which are both the smallest and the most common of U.K. bats. A further colony turned out to be Brown Long Eared Bats, these are medium sized and have ears almost as long as their body. As recently as the 1980's it was discovered that there are three types of Pipistrelle. These are a) common, b) soprano and c) nathusius, this latter being the most rare. Unfortunately it was impossible to tell which of these types of Pipistrelle are living in the Dene.