36
The Essex Naturalist
Dragonfly (Odonata) Report for 1997
Ted Benton
13 Priory Street, Colchester, Essex CO1 2PY.
The most notable change in the dragonfly fauna of Essex in recent years has
been the recovery of Brachytron pratense, the Hairy Dragonfly. By the end of the
1980s it was known only from Langenhoe Ranges and a site on the Dengie
peninsula. The impression I had was that the species was endangered in the
county, with only small and isolated populations. However, by the mid 1990s
there were new reports of sightings of the species in the Lee Valley Country
Park, in the west of the county, from the Southend area, and from several new
sites in north-east Essex. These included both the RSPB's Old Hall Marsh, and
the EWT's Tollesbury Wick, as well as new reports from Curry Farm and
elsewhere on the Dengie (TQ9797, TQ9905). Recording in 1997 indicated
consolidation of these populations of pratense. Graham Smith reported a
maximum of nine individuals on 23rd May at Curry Farm Nature Reserve, with
oviposition being observed in one of the new ponds on 31st May. He mentions
that the species now occurs along the Bradwell Brook from Curry Farm to
Sandbeach Farm on the coast, and also along the Asheldham Brook further
south. At Old Hall, Paul Charlton reported sightings of pratense on three days
between 3rd and 27th May (indicating very early emergence). More remarkably,
Iris Cotgrove reported seeing one or two males of B. pratense on the River
Chelmer on the 6th of June. She returned on 8th to see six males. Two appeared
to be disputing territory. The species was recorded from the Chelmer by D.A.
Ashwell between 1940 and 1960. Iris Cotgrove's observations are the first
records from mid-Essex since those dates. To anticipate next year's report, I have
recently received a report from Geoff Pyman that pratense was seen in the
Waterhall Meadows Nature Reserve on 20th May 1998. The spread of pratense
in Essex coincides with an apparent recovery of its range in the UK as a whole,
with new records from Hertfordshire, North Warwickshire and Nottinghamshire
being reported up to 1996 (British Dragonfly Society Newsletter, No. 29, Spring
1996).
The White-legged Damselfly, Platycnemis pennipes, was also the subject of
concern about its future in the late 1980s. At that time it was believed to be
present only on certain teaches of three river-systems in Essex (the
Chelmer/Blackwater, the Lee/Cornmill Stream, and the Roding). In my
Dragonflies of Essex (Essex Naturalist: 1988), I (mistakenly, it turns out), stated
that it appeared to have been already lost from the Stour. Fortunately, through
the late 1980s and 1990s there has been a steady stream of reports of the species
from the Stour and other rivers and streams in the county which extend its
previously known range. It is unclear to what extent this is a result of more
thorough recording, and to what extent it represents a genuine spread of the
species. Either way, the pessimistic comments made in the late 1980s clearly no