Nice weather for bats – or is it?


November was very warm on our planet – 0.97°C above the twentieth century average and the warmest November on record.

In the UK the highest night-time temperature record was broken and it looks like we might be heading towards a record December too.  A couple of nights ago the lowest recorded night-time temperatutre across recording stations in the UK was apparently over 14°C.

Speaking as someone whose PhD was entitled ‘The winter activity of Pipistrelle Bats‘ (see Fighting for Birds pp22-25) this gets me wondering how hibernating bats will cope with this.

My finding was that Pipistrelles can feed profitably on winter nights when dusk temperatures are above 10°C so you might think that mild winters are good for bats. Maybe they are, but the main way that Pipistrelles get through the winter is by hibernating – dropping their body temperature to very low levels, turning the thermostat right down, in order to save energy. You can’t drop your temperature below ambient (unless you are a fridge using lots of energy) and higher overall temperatures mean higher rates of metabolism and a need for either greater fat reserves going in to the winter or more successful winter feeding.  I wonder whether the balance is favourable or unfavourable to bats like Pipistrelles – and whether anyone is looking at this subject 35 years after I did.

Photo: by Mnolf, Austria via wikimedia commons
Photo: by Mnolf, Austria via wikimedia commons



3 Replies to “Nice weather for bats – or is it?”

  1. No bats seen here yet Mark but a GS Woodpecker was drumming in my garden this morning.
    Merry (or not quite so merry) solstice to one and all.

  2. Although the temperatures are warm enough for bats to be foraging, the heavy rain would surely make for very unfavourable hunting conditions, and I would think that the benefit of foraging would be relatively low, and would be detrimental on average.
    I think Pips might have it worst, as most other species hibernate in caves (or cave-like places) where temperatures will still be fairly consistently low. I have not started my cave hibernation checks yet, but will do in Jan, so it will be interesting to see how numbers alter from past years.

Comments are closed.