Being both a bit of a naturalist and a
bee keeper people sometimes contact me to remove honey bee colonies
that have been constructed between closed shutters and the window.
This is an ideal space and a fairly common occurrence in France with
second homes that are left empty during the swarming season and only
discovered when the owners return to their house or when someone they
know or employ takes a look at the house.
A few years ago, August 2021 to
be precise, one of the houses I was called to was in Charroux,
(86250) by a neighbour of an empty property that was a keyholder,
where the following day I proceeded to dismantle the comb and re
house the bees in a ruchette, (small hive). During a pause in
proceedings the neighbour invited me for a coffee and we then took a
walk though his land chatting about wildlife and conservation in
general. During the course of this chatting he mentioned that they
had a large number of bats every year in their outbuildings which
immediately grabbed my interest. Of course it's not unusual to have a
number of bats in a roof or an outbuilding in France but a large
number clustered close together will invariably be a Maternity
colony or nursery.
We went to look and there were no bats present, but this would be
expected in late summer as the bats that formed the nursery would
have dispersed to individual hang outs, however there were some
photos that clearly showed an important nursery. Having taken the
property owners details and asked if would be OK to inform Vienne
Nature, (the responsible structure for overseeing bat populations in
the Vienne departement), I packed up my gear from collecting the bees
and left.
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Greater Horseshoe bat and Geoffroys bat |
At around this time the ongoing
health situation with my wife took a serious downturn and everything
took second place to my caring for her and I forgot about the bat
nursery until after her death in July 2023. It was following this
that I popped in to the offices of Vienne Nature and finally
mentioned the bats, passing on the contact details to Samuel Ducept,
(chargé
d'études entomologie), and Alice
Chéron,
(chargée d’études chiroptères-faune). Following this Alice made
contact with the owner of the property and a first visit took place
that confirmed the presence of 494 Geoffroy's
bat, (Myotis
emarginatus),
making this by far the largest and most important of the 3 known
nursery sites for this bat in the Vienne. In
June 2024 Alice
Chéron visited the site for a second time and it turned out that two
species of bat were using the same building as a nursery, the second
species being 87 Greater Horseshoe bats, (Rhinolophus
ferrumequinum),
in total making this the third most important known nursery for this
species in the Vienne. It's quite common for these two species of bat
to share the same nursery structure and following the discovery of
this important site it is proposed by Vienne nature to visit and
monitor the bats in June each year.
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Counting Geoffroys bats |
A
maternity colony which is known as a mise-bas in French refers to a
temporary association of reproductive female bats for giving birth
to, nursing, and weaning their pups. The colonies are initiated by
pregnant bats that arrive in late spring but pregnancy in bats is
another of natures remarkable affairs given that actual copulation
usually occurs in the previous year prior to hibernation involving
delayed ovulation where the sperm is stored in the bats uterus and
oviduct, or sperm storage which is where sperm is stored in either
the caudal part of the epididymis or the vas deferens, (sperm duct),
of the male or after copulation in the uterus and oviduct of the
female. Whether in the epididymis or uterus, the bat sperm can stay
alive and healthy for months until it is required.
The
number of bats in a nursery can vary substantially, in part depending
on which species of bat they are but equally there can be a large
variation within a species. With Geoffroy's bats it can be as few as
10 or exceptionally as many as 1,000. Somewhat less for Greater
Horseshoe bats with a maximum of 600, usually much less tending to be
between 30 and 200.
In
Europe as a whole bats have suffered serious declines in their
numbers and as such they are fully protected at both the European and
National level. The positive news is that in the Vienne both of these
species have populations that have shown some small growth in numbers
for the period 1995 to 2015. This is based on winter surveys of their
known hibernation zones and according to the Vienne departements “red
list” Greater horseshoe bats are listed as “Vulnerable”and
Geoffroy's bats are listed as “Least concern”. Overall in France
they are both listed as Least concern but that shouldn't be seen as a
reason for complacency and it is of utmost importance to monitor
populations and protect any nurseries.
A
few brief facts:
Greater
horseshoe bat is Grand rhinolophe in French and Geoffroy's
bat is
Murin à oreilles échancrées hence the alternative name for this
bat in English of Notch eared bat.
Greater
horseshoe bats mainly eat chafers, dung beetles, noctuid moths,
craneflies and caddis flies which they take from the ground
or from the air when flying low along hedgerows, woodland edges and
over water.
Geoffroy's
bats preferred
prey are either flightless, such as spiders or flies of all types
that don't fly at night and can be taken from their resting places in
scrubland, grazing pastures and inside animal sheds and shelters.
In
both cases, as it is with all bats in France, large quantities of
insects will be consumed in one night, well in excess of 1,000 when
it comes to smaller insects.
Both
species hibernate underground in disused cellars, caves, old
underground mines and excavations.
If
you think you have a nursery or would like to take part in winter bat
surveys you can contact your local authorised bat group or contact me via my Facebook page if you need any help with this.
Chris Luck.