Mention the word “bat” and most people might immediately think of summer evenings, heading out for a quick walk before dark maybe, and seeing tiny winged creatures flying along hedgerows or nearly being hit by one as it catches that mosquito you’re stood next to.
While summer time is great – I survey for bats as part of my work as an ecologist – the winter months have their own batty opportunities…
I am an active member of two local bat groups and each winter I join in with some of the hibernation checks. Bats can hibernate in a variety of places so our site visits can be quite different; an old ice house, a railway tunnel, an old WW2 bomb shelter. But one thing all these sites have in common is the conditions that are suitable for bats to hibernate in.
Bats like places with cool, stable temperatures throughout winter to enable them to lower their body temperature and so lower their metabolic rate, which will help to preserve their body fats for as long as possible. Often the hibernation sites I’ve visited have been around 7 or 8 degrees. Another condition is high humidity, as otherwise bats may be at risk of dehydration and the need to wake up to find water will use up precious energy. It is not uncommon to see a bat with beads of condensation on the tips of its fur.
Due to the habit of some species of bats hibernating in obscure or tiny features, such as behind flaking brickwork, within wall cavities, or between cracks in stone or brickwork, it can often be quite difficult to spot a bat, let alone identify it, especially when all you have to go on is the tip of an ear, the tip of a forearm, or a tiny patch of fur!
Armed with good torches and small mirrors, we do our best to find bats and identify them, and so gain an idea as to numbers and how they may be faring over subsequent years.
Please note that these photos were taken with permission of the group leader for the day, and under a project licence.
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