Thursday, 13 August 2015

Aug 12th Burgh Castle

The church at Burgh Castle
Last week when we were at Burgh Castle, we saw a poster on the gates of the church adjacent to the car park. It was advertising a bat watch event in the church itself. It seemed quite interesting and so Dad and I decided to go check it out.

Baby Common Pipistrelle Bats
The event was run by a team of bat experts who study bats that live in churches across Norfolk. We were given a talk about bat anatomy, the species that are found in Norfolk churches and about the conflict between the bats and the churches they inhabit. The urine and droppings of bats do a lot of damage to church artifacts and architecture. It is the team's job to find out which species and how many that are living in every church in the county (there are still hundreds of churches they have yet to survey), where they are roosting, where they emerge at night and how to resolve the problems without causing any disturbance to them. Every British species of bat is protected by law and illegal to disturb a roost site in any way, you need a licence to even get near to a bat. The team also look after injured and orphaned bats and we were shown some tiny baby common pipistrelles that they rescued recently.

Almost time for bats!
It was starting to get dark and was time to go outside with bat detectors (which picks up the high pitched echolocating calls that bats use to locate their insect prey) and watch the bats leave their roost sites. The first to leave were the pipistrelles. There are two species of pipistrelle bat, the common and the saprano, and they can be seperated by frequency on the bat detectors with the sapranos higher pitched than the common pipistrelles. These small bats were swooping over our heads as they patrolled the grounds of the church for the midges that were biting my hands and legs. The occassional buzzing sounds that we could hear on the detectors were the sounds of the bats catching their prey successfully.

Inside the church, brown long-eared bats were emerging from gaps in the ceiling and were gathering in the rafters. With a red filtered torch, we could see them clearly without disturbing the bats too much. As taking photographs could disturb these brilliant creatures, I was reduced to filming them instead, so I apologise for my dodgy camera work as I am not a cameraman. In the video below, you can see those incredibly large ears. These bats rely on stealth to catch their prey and use those amazing ears to detect the faintest rustle of moth wings. The echolocation calls are barely audible on the bat detector, it is no wonder that these bats are also known as the whispering bat. Dad and I are in love with them already as we watch them fly above the rafters with their huge wings.

At this time of year, all the bats that roost in this church are females giving birth. Any roost site during summer months are nurseries. The most commonest species to use churches across Norfolk as a nursery are the Natterer's bat. There happens to be a colony of 40-50 or more Natterer's roosting in this church and use the pipe sticking out of the bell tower to leave into the night. To see them better, the team point an infrared camera at the exit point and we could watch the action on a small tv monitor. Below, you can see one emerging (before I tried to film the exit point myself only to find it was too dark to see anything with my camera), but blink and you will miss it! It was a great end to one of the best bat nights that I have ever been on.
Leopard Slug (I think)

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