Nathusius' Pipistrelle
(Pipistrellus nathusii)
click
on the image for more photos
The Nathusius' is the largest of the Pipistrelles native
to the British Isles and Ireland. The species was thought to be migratory, only
arriving here when blown off course as they travel southwards from Northern
Europe. Since 1997 surveys in Northern Ireland have shown that there is a
breeding population present. However, we still don't know if they migrate to
hibernate elsewhere. In 1996 Jon Russ recorded the first Nathusius' in Northern
Ireland. Consequently, a single individual was found grounded in Belfast that
October and the following year the first maternity roost was discovered.
What to look for
The bats have a very thick fur, which is sometimes shaggy
and is usually the colour of plain chocolate but can be lighter. The underside
fur is tipped with grey. Around the shoulders the fur is longer giving it a
lion's mane effect. The head fur also tends to be a darker shade. The ears of an
alert bat are more pointed than the other Pips and are carried slightly forward.
The tragus is pointed with a blunt tip. The upper side of the tail membrane is
hairy. The forearms, ears and ears are almost black.
Weights and measurements
Forearm 32 - 40mm / 1 inch
Length 46 - 55mm / 2 inches
Weight 6 - 15g / 3rd oz
Habitat and roosts
In Northern Ireland all the roosts are close to water and
parkland and in traditionally built buildings. The buildings are either of
quarried stones or red brick and over 100 years. The largest roost is around 250
in early summer. In Europe the bat is widespread in the north and west.
- Flight: rapid - faster than the other two
pipistrelle species, often deep wing beats when flying in a straight line In
confined spaces is not so maneuverable as the common pipistrelle. Flies 4 -
15 m above the ground
- Habitat: Rides, paths, woodland edge (deciduous
and coniferous), meadows and also over water. Forages at half tree height.
In comparison to the other two pipistrelle species it tends to avoid built
up areas such as towns.
Echolocation
- Heterodyne: The maximum frequency these bats
call at is 39kHz. The males can be identified during August and September by
their song flight. The song is a trill followed by a brief pause and then
another trill. These are best heard at 20 kHz though the trill is sometimes
detectable at 35 kHz. The song flight is most obvious where there are
streetlights that show up the bats. The males repeatedly fly up to and away
from their mating sites without landing. Echolocation is similar in sound to
the common and soprano pipistrelles but the 'slaps' occur at 39-40 kHz. The
repetition rate is lower and more regular than the common and soprano
pipistrelles. Nathusius' pipistrelles often emit mating calls whilst
stationary from a tree or building but also emit them in flight. Most mating
call activity appears to be during the second half of the night. Nathusius'
pipistrelle is perhaps the most vocal of the three species of pipistrelle,
often emitting calls immediately after leaving the roost and continuing
throughout the night at all times of the year.
- Time expansion: The 'shape' of the echolocation
calls is similar to the common and soprano pipistrelle bats. In open
situations this bat may leave part of its FM call or drop it completely so
that just the 'slap' portion of the call is heard but not the 'clicks'. In
this situation the CF portion is slightly lower than normal, at about 36
kHz, and the maximum frequency about 40 kHz. The pulse repetition rate will
be longer. On the other hand, in cluttered environments, the bat may drop
the CF pulse and produce a simple FM sweep. On analysis the sweep usually
terminates slightly above 39 kHz, at about 43 kHz, and the maximum frequency
may be as high as 95 kHz.
See
and hear time expanded call.
