Bats in autumn

In our latest seasonal article on bats in the Isle of Man, Louise Samson of the Manx Bat Group gives us an insight into the creatures behaviour in autumn:

In previous newsletters we have looked at bat behaviour in spring and summer and in this edition we find out what these very special creatures are up to in autumn.

From August onwards the all-female maternity roosts start to disperse and the baby bats born over summer months are learning about their local environment and the best places to catch food.  Bats utilise fine weather nights in September and October to build up their fat stores to get them through the winter.  In addition, male bats attract females using special calls and following mating, the embryo will not start to develop until the spring, saving the females fat resources through the winter hibernation.

The three Myotis bat species found on the Isle of Man, the Daubenton’s bat Myotis daubentonii, Natterer’s bat Myotis nattereri and whiskered bat Myotis mystacinus, are all known to ‘swarm’ in autumn. 

Photo of a Natterer’s bat taken by a licenced bat worker

Swarming takes place at the entrances to their hibernation roosts such as caves and mine entrances. 

Myotis bats gather together and can be seen chasing each other around and males compete for the attention of the females. Research in the UK has shown that these gatherings are made up of many different maternity roosts. The bats may also be gathering to check that their hibernation roosts are still usable and introducing their young to the hibernation roost sites. 

Although small, bats can live for between 10 to 30 years and they will use the same summer maternity and winter hibernation roosts year after year. 

An interesting bat fact is that although bats are very long lived they have a very low occurrence of cancer and this has been linked to their genes.