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insulation. Retiling and underfelting can result
in the exclusion of colonies, but remedial timber
treatment is probably the greatest threat. Over
100,000 buildings are treated annually with
chemicals such as lindane that are lethal to
bats. These chemicals persist in buildings and
bats will pick up poison by inhalation of vapour
or contact with treated surfaces for several
years after application. Non-toxic chemicals
(permethrins) are now available and should be
used. The species most likely to suffer in these
properties are Brown Long-Eared, Whiskered,
Serotine and perhaps Brandt's, because they
favour older buildings.
Trees with holes are important to bats but these
are often felled or tidied when considered
"dangerous". Riverside trees are often removed
for convenience during canalisation and again
this deprives bats of potential roost sites.
Habitat destruction can also affect food supply.
The elimination of unimproved pasture and hedge-
rows, felling of woodland and canalisation of
rivers has greatly reduced the number and variety
of night-flying insects. Cockchafers are now
scarce in Essex yet vital to larger bats (Noctule
and Serotine) after hibernation as they are
around in May. The change in farm practice from
hay-making to cutting grass for silage has meant
that many insects that fly and breed when plants
are in flower are now killed before maturing.
Also the widespread use of forestry and
agricultural insecticides destroys much potential
food, and traces of persistent chemicals can
accumulate in the bats.
So, the case for protection is clearly made -
what does the law say? It is now illegal for