7
early July when the bats (invariably Pipistrelles)
are breeding. The householder thinks they have
arrived to stay and asks for them to be moved.
However, when they realise that the bats will
be present for perhaps 2 months at the most,
that they make less mess than House Martins,
and that they do not constitute a health risk
or do structural damage to the property then the
bats are allowed to stay and return in subsequent
years. For each bat roost a card is kept and
these are followed up in successive years to
try and establish whether any change in numbers
is occurring. The problem comes when the bats
do not return and that group cannot be followed.
For example in Little Baddow I know of 5 roosts.
At roost B, the increase in 1983 presumably
came from roost C. However, at B there were
about 300 bats in early June 1984 but none
bred there. Therefore about 700 bats occupied
an unknown roost in 1984, about 400 may have died
in hibernation the previous winter. May 1984 was
particularly wet and if the females cannot feed
well in May prior to giving birth then the
breeding season will fail, or some other factors
may have been involved. It will be interesting