There
is cons
iderable
interest
in the potent
ial of bat guano as an alternat
ive record of palaeocl
imate
in reg
ions that are devo
id of more commonly ut
il
ised arch
ives. In th
is study, des
igned or
ig
inally to evaluate the potent
ial of cave hosted bat guano to preserve temporal var
iat
ions
in the flux of cosmogen
ic
36Cl,
it was found that the guano depos
it
ional h
istory
is strongly l
inked to cl
imat
ic cond
it
ions. Rad
iocarbon measurements on a 2.7 metre long core of bat guano from Măgur
ic
i Cave, N.W. Roman
ia
ind
icate a max
imum depos
it
ional age of 1195 AD for the base of the core. Depos
it
ion of the lowermost port
ion of the accumulat
ion occurred dur
ing the Med
ieval Cl
imate Anomaly. The cave roost was subsequently devo
id of bats dur
ing a reg
ional cold phase l
inked to the L
ittle Ice Age, w
ith bats return
ing when local temperatures
increased. The rate of guano accumulat
ion then appears to
increase
in t
andem w
ith anthropogen
ic warm
ing. Th
is
ind
icates that bat occupat
ion at th
is roost s
ite
in Măgur
ic
i Cave
is strongly l
inked to reg
ional cl
imate var
iab
il
ity, w
ith hab
itat
ion dur
ing warm per
iods, poss
ibly assoc
iated w
ith the abundance of
insects upon wh
ich the bats feed.
Comparison of large peaks in anthropogenic 14C and 36Cl production associated with nuclear weapons testing indicates downward migration of 36Cl, probably reflecting post-depositional migration within the guano deposit. Elevated 36Cl/Cl at the top of the core in comparison with modern atmospheric values may indicate recycling of bomb 36Cl in vegetation. Therefore, we show that while bat guano contains abundant atmospherically-derived chloride it has severe limitations as a potential archive of atmospherically-derived 36Cl (a solar proxy), because of post-depositional mobility. However, separation of organically bound chloride, or the use of an alternative cosmogenic isotope 10Be, in bat guano, may offer an unexploited solar proxy that contains contemporaneous environmental signals, such as stable isotopes (e.g. δ13C) and pollen, in association with radiocarbon dating.