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Biodiversity
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Mass exodus of bats and dragonflies: the measurement
and conservation of biodiversity
Christoph Zöckler a
a United Nations Environment Programme, World Conservation Monitoring Centre,
Cambridge, UK
Available online: 17 Aug 2011
To cite this article: Christoph Zöckler (2011): Mass exodus of bats and dragonflies: the measurement and conservation of
biodiversity, Biodiversity, 12:2, 116-118
To link to this article: http://dx.doi.org/10.1080/14888386.2011.599053
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BIODIVERSITY
Vol. 12, No. 2, June 2011, 116–118
ON THE GROUND
Reports from all over the world by conservationists and naturalists working on the ground
Mass exodus of bats and dragonflies: the measurement and conservation of biodiversity
Christoph Zo
¨ckler*
United Nations Environment Programme, World Conservation Monitoring Centre, Cambridge, UK
(Received 23 March 2011; final version received 14 June 2011)
The Shwedagon Pagoda near the Centre of Yangon,
the capital of Myanmar, stands on a hill, ringed by
smaller pagodas, a shining golden pinnacle of light
visible from far away both night and day. Its
magnificence rightly makes the building one of the
most popular tourist attractions of the city.
But then every evening, after most of the tourists
have gone, a major natural spectacle occurs. Unknown
to most and unmentioned in any of the travel guides, a
massive exodus of bats recurs each evening around
6 o’clock. The sun has just set: crows and kites, falcons
and the Shikra, an Asian goshawk, are circling over the
West gate in anticipation, like the informed visitor.
Then bats begin to leave the roof tiles of the pagodas.
A few hundred literally pop out, thrown into the
hostile daylight, like popping champagne corks. But
then after a few seconds’ delay, a constant stream of
bats emerges from the tiles like the smoke from a
building on fire. It gets denser and denser, for some
minutes splits into two streams, the bats swarming
together again before dispersing like a mist over the
vast landscape and disappearing into the red sky of the
setting sun.
This awe-inspiring natural phenomenon continues
for about 25 to 30 minutes. The density varies, but the
stream of bats continues well into complete darkness
and can only be seen against the golden background of
the lighted stupa. There might be only one species
involved, for at least 98% are short-tailed bats, though
a few individuals of other species may take advantage
of roosting in the shelter of the mass. A video clip
estimate reveals a total of 500–700 animals per half
second. This means 1.8 to 2.5 million bats fly out from
the pagoda over half an hour. This staggering number
must equal the famous bat roosts in Texas, Mexico or
Borneo. It might even surpass them. No gathering of
any other mammal occurs of that order of magnitude.
It is not clear where these animals are flying, as they
continue until they are lost on the horizon, but we may
assume they disperse across the vast delta around
Yangon where rice growing and small farms predomi-
nate. This rural landscape is still largely without
machines, and no pesticides or artificial fertilisers are
used. Oxen and water buffalo plough the fields so the
rich delta soils do not need additional fertiliser. A huge
number of insects flourish in this animal-based
countryside providing a food store for the bats,
amongst many other creatures. If each bat eats about
500 insects per night, and it is likely to be more, they
may consume altogether more than a billion insects
per night.
Another reason for the immense roost is the
consistency of the Pagoda itself as a reliable and
truly sacred protected site. It has existed for at least
2000 years, allowing a large roost to be established and
gradually develop on this massive scale. No distur-
bance or changes affect the roost by day and the food
source is undiminished. The bats’ droppings are
carefully harvested by the monks and sold to farmers
and gardeners as valuable fertiliser – and the cycle of
nutrients is closed. The mass exodus is one of the
world’s natural wonders, an astonishing spectacle that
also tells of the lavish abundance of biodiversity.
This abundance is something we no longer
encounter elsewhere and we seem to have lost it in
most natural and rural ecosystems of the developed
world. In Myanmar we know of at least one other such
roost in the south of the country. There was a similar
one in Phnom Penh, also hosting over a million bats,
but this was destroyed as the roost created too much
‘dirt’. Bats have not always had the finest of
reputations and are persecuted all over the world.
These bats in Yangon appear to have been protected
by the monks.
*Email: christoph.zo
¨ckler@consultants.unep-wcmc.org
ISSN 1488–8386 print/ISSN 2160–0651 online
ß2011 Tropical Conservancy
DOI: 10.1080/14888386.2011.599053
http://www.informaworld.com
Downloaded by [Mr Stephen Aitken] at 11:01 15 February 2012
Another sighting from this unusual country is worth
mentioning. The wildlife-interested visitor to the
Pagoda and to other parts of Yangon may notice the
constant presence of dragonflies. Scanning the stupa
and golden roofs he can see dragonflies everywhere.
In fact there is little space in the air not occupied with at
least one or two, usually many more. The whole sky
over Yangon seems virtually saturated with dragonflies.
Figure 1. Short-tailed bats emerging from the Shwedagon Pagoda in Yangon, Myanmar.
Figure 2. Dragonflies fill the evening sky in Yangon.
BIODIVERSITY 117
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Unlike the Shwedagon, few tourists travel deep into
the Ayeyarwaddy (Irrawaddy) delta. This fertile
countryside is among the most populated in
Myanmar. Most people here live off the countryside
or by fishing in the rich delta waters. There are no
tourist facilities and little reason for foreigners to visit.
The few who do come, notice that in village after
village, field after field, with the first sunlight come
masses of dragonflies. As their density varies, counting
them is difficult, but at times several thousand hover
over a single paddy, and an estimated 50,000 dragon-
flies may be found over the channels and alongside
wet rice fields after half an hour drive. Calculating
this for all the rice fields and channels of the delta
the total could easily be several million dragonflies.
Again, these are mostly unnoticed. Perhaps an FAO
representative of the World Food Programme visiting
the troubled delta region after cyclone Nargis struck
it three years ago, might at first glance mistake them
for locusts, but on a closer look saw they were only
dragonflies and nothing to worry about. Like bats,
dragonflies also feed on insects, but during the day.
Dragonflies spend most of their life-time as larvae
under water. It is possible that they all emerged from
the rice paddies, but more likely they migrated into the
region from further south. We do not know for sure,
but it is less important than the fact that such
biodiversity richness is hardly observed anywhere else
on the planet.
Will the bats and dragonflies remain if Myanmar
finally develops and adopts a modern style of farming
with fertilisers, tractors and pesticides? There may be
less of both, but at the moment, both bats and
dragonflies reflect an abundance of life and biodiver-
sity that we seem to have lost long ago in a world
where petrochemicals and pesticides have killed off so
much life and diminished biodiversity, far beyond rural
Myanmar.
Figure 3. A macro-view of Pantala flavescens. (Photo by Keith D.P. Wilson.)
118 C. ZO
¨CKLER
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