We have been busy using our in house roped access, tree climbing and confined space training for a number of development schemes recently, mainly searching for bats and their roosts. With works proposed during the winter hibernacula period for bats, it is essential that these surveys are completed in advance. Trees as well as bridges and rock faces have been surveyed taking us into some challenging locations. During the winter (November to March) bats are torpid in a sort of suspended animation and there is the potential to cause disturbance when working within 30m.
Bats have amazing abilities of endurance able to slow their metabolism and breathing down to conserve energy. Choosing the right conditions for winter roosts is important – they require cool and stable temperatures, reasonable humidity and safe locations out of reach of predators. Not much is known about the location of bats during the winter months, although surveys of potential winter roost sites, which can include buildings, caves, rock faces and enclosed chambers in bridges are revealing new information.
With little or no insect life available they need to use what fat reserves they have built up ahead of the hibernation period, to sustain them for 4-5 months. Any disturbance that may rouse them from their slumber can put a serious burden on their fat reserves (as much as 10% of their body weight), which can make the difference to their survival. When you consider they only way 5-8g this is a remarkable feat of endurance through a Scottish winter.