Bite of the Vampire:
Bat Breath Gives Clue to
Shifting Latin American
Environment
Research published in
the Journal of
Comparative Physiology
has shown that Latin
American vampire bat
populations have
switched blood meals
from rainforest mammals
to cattle, which
indicates the changing
of rainforest ecosystems
into pasture land. The
move has resulted in the
expansion of vampire bat
numbers.
The results, published
by ecological
physiologists, were
found by analyzing the
stable carbon isotope
ratio of exhaled CO2
from captive bats. These
were fed with blood that
was labelled with the
stable (non-radioactive)
isotope carbon-13 and
then monitored for the
time period between the
blood meal and the
appearance of labelled
carbon atoms in the
exhaled breath.
According to team member
Dr. Christian Voigt:
“Vampire bats used the
freshly ingested blood
very fast to fuel their
metabolism; after less
than an hour the stable
carbon isotope signature
of the vampires’ exhaled
breath was similar to
that of their latest
diet.”
Researchers then
compared this
information with the
breath from free-ranging
bats.
Disappearing rainforest
“The potential victims
of vampires in Costa
Rica are either cattle
or rainforest mammals
such as tapirs and
peccaries. These two
groups of animals feed
on isotopically distinct
plants which are grasses
in the case of cattle
and herbs or shrubs in
the case of rainforest
mammals. Therefore, we
expected that the stable
carbon isotope signature
in bat breath would
change according to
their diet,” continued
Dr. Voigt.
Samples clearly
indicated that the last
blood meal was almost
exclusively from cattle.
According to the
researchers, this is not
an indication that the
bats prefer cattle
blood, but that it is
easier to find than
their traditional prey.
It also demonstrates -
they suggest - the large
impact of converting
rainforest into pasture. |
