BATS IN BARNS IN HERTFORDSHIRE AND ESSEX
Patty Briggs
The recent growth in the number of barn conversions in the East Anglia
area is posing yet another threat to British bats. Rarely will a bat survey
have been carried out. Ask a farmer if there are bats in his barn and his
usual answer is "no". But that doesn't mean that he's right. How
many farmers would want to stand in a barn at 10.30 p.m. to see if
bats emerge from the woodwork? Most would rather have their feet up
in front of the TV after a hard day's work in the fields. Large numbers
of these old barns are now redundant and are being converted into
luxury dwellings. Most of these barns will have bats in them that
nobody knows about.
The problem first came to light in Hertfordshire in 1991. The new
owner of a barn that was being converted was concerned that a single
bat that she had seen was about to be walled in behind the new
bathroom wall. The bat had disappeared by the time the local
batworker arrived. The only clue to the presence of bats was a modest
sprinkling of fresh droppings beneath a tie beam on the end wall: the
bats had to be there somewhere close by. Because the first floor had
already been put in, it was relatively easy for the batworker to search
the tie beams which are usually beyond the reach of normal ladders. A
hole the size of a 50 p coin leading into a hollow mortise joint in the tie
beam was found. Using a small pen torch, it was possible to see the
nose of one bat about 25 cm back within the old thick beam.
Returning at dusk, instead of the predicted single bat, 35 Natterer's bats
emerged from the beam - all about to give birth! These bats are rare
bats in Hertfordshire. This roost was only the second known breeding
site at the time in the county. Very few summer breeding sites are
known in the UK. The bats emerged from the beam and flew within the
roof space of the barn before leaving to feed. Some were heard landing
and further observation work revealed that some of the bats were
disappearing inside yet another mortise joint of another tie beam that
was going to be within the new dwelling area. The bats obviously had
nowhere else to go as they had refused to leave despite reroofing,
timber treatment, shot blasting of the timbers, and stud work all
completed with endless banging of hammers. The thickness of the
beams must have given the bats a certain amount of protection. In
certain areas, the construction of the barns frequently incorporates large
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