The Bats of London
This is an introduction to the species of bat that can
be seen in Greater
London, where they can be seen, and some ideas on how to tell them
apart. This
is often difficult however, and some species can only be reliably
identified by
experts in the hand. Bat detectors are
a valuable
tool, and can often reveal the presence of bats when they are difficult
to see
when flying close to trees in the dark. Why not join the
London Bat Group and go out in the company of more
experienced bat watchers
and learn the "tricks of the trade".
 The
pipistrelle, Pipistrellus sp.
These tiny animals weigh about 4 to 6 grams, have a
wingspan of 19 to
25cm and eat midges, mosquitoes and other small insects that they catch
and eat on the wing. A single pipistrelle can eat up to 3000 midges,
caddis flies, mosquitoes and other similar small insects in a night.
The pipistrelle is the
most common species of bat in Britain, and mostly roosts in houses
under eaves
and soffit boards which means that their roosts are found more often
than other
species.
They can be seen after dusk as they leave their roosts or where they
feed in
woodland, over water, along hedgerows and even over gardens in almost
every
part of London. The pipistrelle has been recently recognised as
consisting of
two separate species (Pipistrellus pipistrellus and P. pygmaeus)
after research into population, genetics and habits, and a third rare
species
Pipistrellus nathusii is now known to breed in
the UK. All three are present in Greater London and the London Bat
Group intends to
determine their distributions.
The noctule, Nyctalus noctula
The noctule bat is one of the largest bats found in
Britain, and is often
the first to emerge from its roost, sometimes before sunset. Weighing
some 18
to 40 grams and with a wingspan of 32 to 40cm it has a sleek golden
coloured
fur and broad brown ears.
Although still a fairly widespread species in London, the noctule seems
to have
declined in recent years. This is possibly due at least in part to over
management of trees where it exclusively roosts in woodpecker or rot
holes.
The noctule feeds on moths, beetles and mayflies and typically feeds
high over
woodland, parkland and water bodies. Good sites for seeing noctules are
Hampstead Heath, Berwick ponds in Havering, over the Thames in
Teddington,
Oxleas Wood in Greenwich, and even in Hyde and Regents Park in central
London.
The Daubenton's bat Myotis daubentonii
The Daubenton's bat is a medium sized bat weighing 7 to
12 grams and with
a wing span of 24 to 27cm. It was often called the water bat in the
past
because of its distinctive habit of flying in a level flight about 10cm
above
the surface of water bodies such as lakes. The Daubenton's feeds on
small flies
such as caddis flies and midges and roosts in trees or tunnels and
bridges which
are generally near water. Daubenton's can be seen mainly in west London
sites
like Wimbledon Common; the Grand Union Canal in Hillingdon and Bushey
Park, but
can also be found on sites like Hampstead Heath and Beech Hill Lake in
Barnet.
Natterer's bat (Myotis nattereri)
The Natterer's bat is similar to the Daubenton's, and
individuals have been found in Highgate Woods
and the grounds of Chiswick House and in 1996 a tree roost was found in
Hillingdon. Work is being planned by London Underground Ltd to enhance
a major autumn site for this species that has recently been found near
Highgate Wood.
 The
brown long-eared bat Plecotus auritus
As suggested by the name, the brown long-eared bat has
remarkably large
ears which are nearly as long as its body. It is a medium sized bat
weighing 6
to 12 grams and has a wingspan of 23 to 28cm. Although nationally, the
brown
long-eared is regarded as the second most common species, it is less
common in
London as it appears to be less well able to survive in urban
surroundings.
This animal is the bat that is most frequently found roosting inside
roof
spaces where it likes the ridge beams of older properties.
Its habits of emerging very late when it is quite dark, keeping very
close to
trees when hunting and not travelling long distances means that the
brown
long-eared is difficult to find. Even London Bat Group experts have
spent many
evenings searching for this species with no success, even when we know
the bats
are definitely there!
The serotine bat Eptesicus serotinus
Another large bat, weighing 15 to 35 grams and with a
wing span of 32 to
38cm the serotine feeds on flies and moths but is particularly fond of
cockchafer beetles which it can catch by landing on the ground. The
serotine is
mainly found in the outer boroughs of London such as Bromley, Havering
and
Sutton where it feeds over mature parkland or pastures.
Other Species
A number of other species of bat are occasionally found,
especially in the
outer London boroughs. The Leisler's bat (Nyctalus leisleri)
is a
smaller cousin of the noctule and weighs 12 to 20 grams and has a
wingspan of
26 to 32 cm. There is one known summer roost of Brandt's bats (Myotis
brandtii) in Hillingdon otherwise this bat is extremely rare
in London, and
for the similar whiskered bat (Myotis mystacinus)
there are only
occasional individual records.
London Bat Group Database
The London Bat Group holds data on London's bats in
Recorder
2002 from the
National
Biodiversity Network, but is equally
sure that this has significant gaps. The following map shows where we
do have
information from post 1990. The group is in touch with a number of
individuals and others to obtain additional
information, and is planning a series of visits to sites to obtain
further information. If you have any information -
especially that which will fill in the gaps please let
us know.
Map Produced in
Recorder 2002 using map data from
the London Biodiversity Records Project at the London
Wildlife Trust
All enquiries from developers /
consultants regarding obtaining
bat data should be directed to the London Biodiversity Records Project
at the London
Wildlife Trust, who now act as our agents for this.
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