caves of North Yorkshire make an unlikely
clubland, but every night throughout the autumn,
clients arrive together from up to 60 kilometres
away and circulate the subterranean establishments
in their thousands. This is where bats come
to hang out at Halloween and search
for a mate. Conservationists are calling for
their seedy underworld to be protected, so
that both bats and humans can
continue to enjoy the caves.
animal the brown long-eared bat,
widespread in Yorkshire though in decline
University of Leeds biologist Professor John
Altringham explains: Bats spend the
summer dispersed in small colonies across
the region, and opportunities to meet fresh
faces are few and far between. Bats risk problems
of inbreeding if they only find mates within
their summer colonies, and the autumn cave-visiting
behaviour seems to be an evolved strategy
to avoid mating too close to home.
New DNA evidence backs up the inbreeding avoidance
picture, and it seems that clubbing is vital
for bat populations to thrive. If the researchers
are right, this puts the caves at the heart
of bat conservation efforts, and threats to
the caves would leave the party animal bats
all dressed up with nowhere to go.
Fears for public safety mean many caves and
mineshafts are now blocked to prevent accidents.
Altringham said: My nightmare scenario
is a safety conscious individual or organisation
blocking the entrances to an important underground
site theres a group of caves
in the North York Moors thats used by
an estimated ten percent of the national population
of Natterers bat. While that one is
safe, others may be under threat, and closing
a cave in winter could entomb thousands of
bats in one fell swoop. Where cave entrances
need to be shut, bat-friendly grilles should
be used rather than concrete or trapdoors.
Altringham and PhD student Anita Glover have
shown that the ability of the bats to penetrate
the caves themselves is astonishing
they fly kilometres underground, sometimes
through passages just a foot across, spiralling
into the ground down narrow potholes, and
exploring the entire cave network.
Ease Gill in the Dales contains a network
of 70 kilometres of tunnels in a recent
trip, Altringham and Glover spent 10 hours
underground, moving from one cave entrance
to another, and found traces of bats throughout.