Bats through the Seasons – Winter
Greater horseshoe bats, like every British bat species, live complex seasonal life-cycles that follow the changing temperatures and availability of food throughout the year. So what are Devon’s greater horseshoe bats up to right now?
At this time of year, when the days are at their shortest and temperatures are dropping, the bats will be settling down for hibernation over the coming winter months. Having mated in the autumn, males and females turn their attention to fattening up for winter and finding a safe and suitable place to hibernate.
From late autumn until spring, when the insects they feed on are at their scarcest, greater horseshoe bats seek out caves, abandoned mines, tunnels and cellars where they will be sheltered from the elements, but not so warm that they can’t stay asleep! Generally, hibernating horseshoes prefer temperatures to be between 5 and 11 degrees. Once a suitable site has been chosen, they hang themselves upside down and wrap their large wings around themselves like a blanket. Interestingly, greater and lesser horseshoe bats are the only species to exhibit this characterful bat behaviour!
Like many mammals that hibernate, bats conserve their energy by slowing down their metabolism, heart-rate and bodily functions and entering a state of torpor. Generally, greater horseshoe bats gather in small groups in these caves and tunnels – known as their hibernacula – and huddle close together to regulate their temperature and limit water-loss. One thing that makes greater horseshoes a little different from other species of bats in the UK is that they are known to be light sleepers, emerging from hibernation fairly frequently during the winter, heading out on milder evenings for occasional foraging trips, or simply to have a drink or adjust their roosting position.
When they finally finish hibernation will depend on the weather next year. Warmer springs are good news for bats as they mean more insects and a chance for the females to feed for longer before giving birth to their pups. But for now, greater horseshoe bats across Devon are preparing to weather the cold, tucked away in those all-important caves.Tags: greater horseshoe, hibernating, seasons