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Brown Long-Eared bats are the species that have
suffered most from the use of tonic chemicals
in loft spaces. They are most often found in
older properties, in lofts free of cobwebs.
Family groups tend to stay together and this
bat is the second commonest in Essex. However,
the roosts contain only small numbers of
bats. A practical problem that occurred last
summer involved a school house that needed to
be treated during the summer holidays. Heavy
duty polythene was used to screen off the bats
so that the loft could be sprayed in two
sections, minimising the disturbance to the
bats. Last summer a project was under taken to
go back to lofts that had been sprayed with
permethrin in previous years. In each case
the bats had returned to the lofts and in two
cases bred in the loft, showing the value of
using non—toxic chemicals.
Other species such as the Noctule are dependent
on trees but to date only two roosts have been
found - one in an ash tree at Little Baddow and
the other in sweet chestnuts at Thundersley
However, they can be seen flying with a charac-
teristic tumbling flight at feeding sites such
as open pasture and gravel pits. A member of
the same family, the Leisler's bat has recently
been found in Essex. Of six known roosts of
this bat in the country, three are in Essex -
in Danbury, Aveley and Blackmore, with other
possible roosts in Collier Row and Great
Burstead. This species is rare over most of
its range in Europe but large colonies are
widespread in Ireland, the stronghold for the
species. Traditionally, the Leisler's is a
forest bat, but in Essex it has been found
occupying newer houses on estates in both gable