February Hibernation Survey at Harlaxton

Last Sunday was one of those beautiful days when everybody feels spring is just around the corner. The garden was filled with birdsong and sunshine, neighbours decided it was finally time to venture out and sweep those autumn leaves, daffodil bulbs bulged yellow at their tips where flowers are just waiting to appear.

What better day to descend into a sealed up tunnel, feeling the temperature drop steadily on a headlamp-lit thermometer, to search for hibernating bats!? Along with another member of the Lincolnshire Bat Group, we gallantly left the sunlight behind to see what we could find.

Entering the tunnels

In the past we have come across hibernating barbastelle bats, a rare species in the UK and here, at almost the northerly limit of their range, but sadly this time they were absent from the deep cracks which staircase down the brickwork where the tunnel curves.

Several years ago the Bat Group put up boxes in the tunnel, to provide a greater range of roosting opportunities and in here we did find some bats – two boxes had brown long-eared bats sleeping soundly inside, their long ears tucked behind their wings with only the tragus – the fleshy projection within the ears – apparent.

Hibernating brown long-eared bat

Only one of these bats was present during the January survey which means that some time in the last month, the other has flown and found this as a new place to enter torpor. This is not uncommon, bats will rouse during warmer winter weather and will often feed briefly before returning to their torpid state.
Along with the bats were around 60-70 peacock butterflies, all with their wings tightly closed and apparently oblivious to our torchlight as we passed by, careful not to disturb them. Many had damaged pieces of wing from last year – the first butterflies of the year are often tattered old veteran tortoiseshells, peacocks and brimstones.

Hibernating peacock butterflies

A number of herald moths were also present, including the pair pictured below who appeared to be hibernating upon a spiders web! I would love to hear any feedback on this interpretation – I do not think they have fallen prey to the spider as this same pair were present last September when I checked the boxes were ready for the winter and are apparently still alive and well! They will take flight when the weather warms, sometime between March and May.

Hibernating herald moths

If you are interested in joining the local bat group, visit their webpage for details – there are events throughout the year that you can take part in. For details of your local group if you are outside of Lincolnshire, the BCT webpage has all the info.

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