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new houses — commonly an housing estates less
than 20 years old. In this situation -female
bats group together in nursery colonies to
raise their one young. When the young are
weaned, the group disperses. Bats often have
several roosts close to one another and it's
not unusual to -find them moving from one to
another in June ana July, perhaps as a response
to disturbance or temperature change. Although
we know where Pipistrelles spend the summer,
they are difficult to find in winter. It is
likely that the autumn is spent in mating
roosts De-fore dispersal to hibernation sites,
but no communal hibernation occurs in caves.
Over the last few years, individuals have been
found in a pile of breeze blocks, behind wood
cladding and in trees, but it is very difficult
to find animals 11/2 inches long and weighing 5
grams.
A large bat that occurs in small numbers in
60th new and old houses is the Serotine
(Eptesicus serotinus). This species has a
15 inch wingspan ana preys on large beetles and
moths. Whereas a Pipistrelle colony may hold
over 600 bats, Serotines occur in small numbers
ana the usual roost size is 15—20 bats. I
have round them in gable ends of new houses as
well as in roof spaces adjacent to hot water
tanks. Again they will use several different
houses in an area - a colony in Wickford use at
least live. Serotines nave often been found
to carry their young with them from roost to
roost. Recent: studies suggest that only 60%.
of females in a colony creed in a year and so
any increase in population will take a long
time.