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DRAGONFLIES AND NATURE CONSERVATION
Dragonflies have existed on the earth for over 300
million years. They belong to a much older group
than most of their prey today: their larval and adult
diet must have changed a great deal over the years.
Their ability to eat almost anything that moves and
is not too large has stood them in good stead.
During the last glaciation, some tundra dragonflies
may have been able to survive in those parts of
southern England and Ireland which were not
glaciated, but the dragonfly fauna must have been
exterminated over the rest of the country. The
early separation of Ireland from Britain (perhaps
before the end of the glacial), and the later
separation of Britain from the continent made
recolonisation more difficult when the climate
improved. It is not surprising that Britain and
Ireland have an impoverished dragonfly fauna
when compared with the adjacent continent (see
Table 1 in the Introduction). Today it is difficult to
decide which continental species are absent from
Britain and Ireland because the habitat or climate is
not suitable and which because they have failed to
cross the sea.
Since the last glaciation, there have been three
main ecological situations to which dragonflies
have had to adapt. First, there was the natural
scene when man was a rare hunter/gatherer and
had little effect on his environment. At that time,
most of Britain and Ireland was covered by forest,
but there were many tree-fringed lakes in the
north, and large areas of swampy woodland and
marsh in the valleys of lowland river systems.
Apart from tarns, lochans and meres, small bodies
of water were provided by ox-bow lakes and
temporary pools made by fallen trees blocking
streams, and by beaver (Castor fiber) dams. It is
tempting to speculate on the dragonfly fauna of that
time, but we have no direct evidence of it:
dragonfly fossils are extremely rare in the
Quaternary (Buckland & Coope 1991).
The second period was that of traditional
agriculture based on manpower and horsepower.
The forests were felled with flint and then metal
axes, with a peak of activity in the Iron Age/Roman
period; by the end of the first millennium AD, a
large part of lowland Britain and Ireland consisted
of agricultural land, though extensive wetlands
survived in such areas as the Fens, the Somerset
and the Humberhead Levels, and the Bog of Allen
in the central Irish plain. During the period of
traditional agriculture, and particularly from the
17th century onwards, swamps and meres were
systematically drained, but, at the same time,
thousands of ditches and farm ponds were dug.
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Locks on rivers produced stretches of still water, as
did dams supporting water mills and early iron
works. The network of canals built in the 18th and
early 19th centuries provided very large areas of
dragonfly habitat. Nearly every large country
house had a lake constructed in its park. Large
areas of lowland heathland containing raised and
valley bogs remained. For many species, outside
of upland areas, there were probably more
dragonfly habitats in the period of traditional
agriculture than in the preceding period when
forest predominated.
The third period started in the lifetime of some
contributors to the Odonata Recording Scheme. It
is the period of industrial agriculture, when
machines have replaced horses, and herbicides
the hoe, when deep drainage has been possible,
and the vast majority of crops are treated with
insecticides and fungicides. This period had its
origin before the Second World War, but did not
really become established until the 1950s. The
shift from traditional to industrial agriculture has
been largely detrimental to dragonfly habitats and
hence to dragonflies. Yet, at the same time,
developments in other industries have produced
new habitats which are beneficial to dragonflies.
The changing distribution and status of dragonflies
recorded in this Atlas reflect the extent to which
species, which had become adapted to the
habitats produced by traditional agriculture over
several thousand years, have responded to the new
landscape which has arisen in less than half a
century. In the following appraisal the probable
effects of the changes on different species are
described so that we can identify the conservation
action which is now necessary in each type of
landscape.
Farming is the most common land use in England,
Wales and lowland Scotland, and much of Ireland.
In lowland areas, the change from mixed farming
to cereal and other arable production has had a
considerable effect on dragonfly populations.
Farm ponds, formerly used as drinking places for
livestock, have been seriously neglected: often
shaded by trees, overgrown with vegetation, or
filled with rubbish. As a result, even common
species such as Coenagnbn puella and Sympetrum
striolatum are now absent from large areas of
farmland. However, such losses can be made
good. Many ponds still exist, and if excessive tree
growth and vegetation is cut back, and if they can
be kept free of water polluted by slurry or
fertilizer, they can be restored effectively
However, overgrown ponds may harbour rare
invertebrates and plants that are adapted to such