Today, I joined the SilverTrees Bat Monitoring Team… Rose from Staffordshire Bat Group and Rob Winstanley, to take a look at the bats present in the bat boxes at SilverTrees. You may remember I also joined them back in May on their Spring monitoring. Today, we were joined by David Gregory-Kumar and the BBC Midlands Today Team for a piece that will go out towards the end of October.
Rose and Rob check all the boxes at SilverTrees in Spring and Autumn , noting what species are present. In some instances, the individuals are weighed and measured to give an indication of the healthiness of the population and also to help with ID on some species. At this time of the year, the bats are preparing for hibernation. We are hoping that the long summer has meant plenty of insects to ensure that the bats reach a healthy weight to see them through the winter months. Bats, however, have a limit to the amount of fat they can lay down as they still need to be efficient hunters and that means being able to fly! Being too heavy would mean that they would not be able to fly well. Most of the bats will not actually hibernate in the bat boxes at SilverTrees. Bat boxes like this are generally used as summer roosts and they will have a favourite place for them to spend the winter. This could be in a tree, loft space or similar.
We did find a couple of boxes with numerous Pipistrelles huddling together. Sometimes these are a male with numerous females. Bats mate at this time of year and the female then stores the sperm until the spring. As soon as conditions are good, the female bat needs to become pregnant and, after a long hibernation, they don’t want to be looking for a mate at this time. It makes sense to mate in the Autumn when they are fat and healthy after a long summer of feeding and then to ‘choose’ when to initiate the pregnancy! The bat is then pregnant for between 6 and 9 weeks, depending on species, climate and availability of food. The females often gather in a ‘maternity’ roost where the youngsters are left whilst their mothers hunt for food. They are suckled until they are 4-5 weeks old when they venture out to hunt for themselves.
We worked our way around the bat boxes, with Rob climbing up, carefully blocking the entrance with a duster before opening slowly and peeping inside. If there were bats present, Rose (who is qualified in Bat monitoring) would go and check and, in some cases, bring an individual down for weighing and measuring.
Being able to see these amazing creatures in the hand is the highlight for me!
David weighs one of the bats
Weighing the Noctule
Rose measure the Noctule’s forewing
A stunning Noctule