WE GOT SERIOUSLY INVOLVED IN THE COLLECTIVE
KNOWLEDGE PROJECT IN 1990,WHEN THE WELSTEADS PROVIDED US WITH LISTS
OF SITES THAT NEEDED CHECKING.
Consequently we acquired a lot of site and species data. To circulate this information in 1996 we compiled a summary of our findings at the Species level and extracts are given below.It is possible that in 2001 we will compile another summary with comparisons.
Calopteryx virgo. Cleanliness of water seems to be a prerequisite for this species and it can vanish as quickly as it appears.There are also only a few local sites where these conditions occur.If not visited during the season there are no fresh records.
Most of the records were for singles and does lead to the suspicion that they were dispersed individuals and the main population was elsewhere.At Fleet Pond the Brookley stream has shallowed and the treecover is now considerable and the species seems to have gone.
Calopteryx Splendens. This species seems to prefer a mud-lined waterbody with not necessarily the best quality water.This enables reasonable quantities to appear on the Basingstoke Canal.Larger numbers are recorded at Thatchers Ford,at the confluence of the Rivers Blackwater and Whitewater,also at Artington on the River Wey.Locally this species appears with Brachytron pratense,at the Ash Embankment thus getting the new season under way.
Exuvia are found on vegetation over water,suggesting a straight climb up some convenient stalk in the water.Females remain some distance from water usually in hedgerows.This is dangerous territory for flamboyant males,as male Chaffinches collect them,strip the wings and take the remainder to their nest.Normally the male is found in quantity either flying low over water or on a selected territory by the waters edge.
Lestes sponsa. This species does not take kindly to their grassy areas becoming overgrown with bramble and birch scrub.A number of local populations have vanished due to this problem.There also seems to be some seasonal effect as a result of changing water levels in heathland ponds.
Some of the variation in seasonal counts are due to the actual number of visits to Thursley and Boldermere.the latter has had its water level raised to permit watersports and the results are not yet known.
Although found in longish grass,the adults also enjoy reed beds,close to the bank,as roosting and territorial sites.Once paired they seem in no hurry to complete,unlike some other species.
Platycnemis pennipes. The main records for this species are from river sites although we have found wanderers up to a mile from their likely source.Thundry Meadows and Artington are on the River Wey,Goring on the River Thames and Thatchers Ford at the confluence of the Blackwater and Whitewater.Some were found at Norris Bridge and presumably came from a section of the Gelvert stream.The old Basingstoke Canal site is now under the Relief Road but is possible that a population has survived.The Boldermere and Wisley populations are probably related but have not been sourced.In Wellington Country Park there is a discreet population at the western end of the Lake.
In each case pennipes has been found in areas of high grass usually with bramble and nettle.The bankside vegetation was cut at Bentley and we have not found them since.
Pyrrhosoma nymphula. This species starts the local odonata season,but emergence continues into the summer.We have found them besides rivers and streams,at the canal bank and in ponds and ditches.The cleanliness of the water does not seem to be a major factor.In some small streams they appear to be the only odonata present.
One of the largest populations was found at Brookwood Lye on the Basingstoke Canal where there was ample bankside vegetation for territorial behaviour and a shortage of other species.At Fleet Pond after the bankside vegetation was cleared there appeared to be a considerable drop in the recorded population.Tidying up by conservation groups or wardens may do more harm than good.
Ischnura elegans. There are a considerable number of sites where this species can be seen in small numbers.We are fortunate to have the Ash Embankment on the Basingstoke Canal where high counts are possible together with the female colour variants.
Counting of ovipositing is not easy with this species as it disappears into vegetation with other blue damselflies.Preferred roosting positions seem to be cut-outs in reedbeds where up to 20 males at a time can be found.
Enallagma cythigerum. There seems to be a division between large and small numbers observed,some of this may be due to preferred sites.The larger counts were at extensive lengths of water with plenty of vegetation.These included Eversley Gravel Pits,Boldermere,Thursley NNR,and sections of the Basingstoke Canal.
Emergent and immature E.cythigerum seems prepared to move away from water into meadows,as at Lakeside,also onto heathland.
When counting on the Basingstoke Canal,we only use one bank which gives minimum numbers for that record.on most of the pond sites we can make a circuit to see what is in the waterside vegetation.For this species we also look in the grass and vegetation of the surrounding area.
Coenagrion pulchellum. Sightings of this species are divided between going to a good site for practice in recognition and photography and a few local sites where the species has been previously recorded.
Langhams Pond at Runnymede was visited in 1991 and 1992 to rediscover the species.Only a few were found in dispersed areas.One lot in reeds at the east end of the pond and the second lot in a marshy area further towards the roundabout.
John Pontin has recorded C.pulchellum on the Ash Embankment previously and we have looked for the source of the population.In 1994 and 1995 we have seen single males on vegetation in Lakeside but have not yet found their breeding site in the many ditches around Lakeside or the fishing ponds.
Coenagrion puella. Large sightings of this species seem to depend on several hours of hazy sunshine in the middle of the day.This seems to bring them out of hiding.
It has been noticed in large counts of C.puella on the Ash Embankment that a number of blue females can be found.None were convertible to C.pulchellum.
Ovipositing occurs into water borne plant debris in flashes and cut-outs in the Canal.
Erythroma najas. Any reduction in water plants including waterlilies seems to cut down the visible number of this species.Refurbishment of ponds and increased boat traffic on the Canal has reduced the available vegetation during the observation period.
It would seem that emergent and immature E.najas do not move far from water as we have not found them in the meadows some distance from water unlike C.puella and E.cythigerum.
We do have a local problem from over-management of water-bodies for recreational use resulting in dramatic clearance of bankside vegetation which does no good to either odonata or lepidoptra.
Ceriagrion tenellum. There are few local populations of this species and they tend to be fragile.Conservation effort of the wrong sort can remove this species from a site and they are not known as ready repopulators of sites.There is a local dispute on the distance the wanderers of this species will travel,some put it down at a hundred metres others at a kilometre.But providing that there is a sphagnum lawn available a small residual population seems to survive although seldom seen.
All our sites were shallow ponds and ditches in heathland,with quantities of sphagnum.Singles were seen by the waters edge on vegetation.
Males take up position on gorse,away from water to meet the females who are roosting nearby.Pairs move round the gorse in sunlight before returning to the waterbody.But few are seen ovipositing.
Gomphus vulgatissimus. Worthwhile sightings in our area are dependant on a visit to Goring at a suitable date.
Being at Goring on an emergence day is an unusual experience with a mass emergence up the bank of the Thames.The nymphs climb onto the grass,other vegetation and the brick wall of the railway viaduct.As we found in 1991,on a visit the following day the dispersal is swift.We have been told that the emergents travel up to a mile to the local woods away from water for safety.Certainly the exuvia seem to vanish as quickly,whether by decay,trampling by consumption by insects or local small mammals,we are not sure.
It seems that wanderers come down the Thames into its tributaries and occasional adults are seen.Also occasional small emergences take place as in the one at Thatchers Ford in 1994.But we don't think it was repeated although it is not an easy site to check,with high banks which means finding a team to wade along the river to check the vegetation for exuvia.
Brachytron pratense. Our main source for this species is a fairly short but prolific section of the Basingstoke Canal starting at Claycart and ending at Curzon Bridge.This is the section on which we would expect to find exuvia although the males of the species can be found wandering on other sections.They have also appeared on larger water bodies as wanderers.
We have two records of emergence at ponds,one at Normandy Pond where we saw the emergent with its exuvia and the other reported to us at Willand Lake where only the exuvia was found.
Emergence seems to be mainly an overnight event with the nymph climbing vegetation over water to a height that seems to vary with the amount of wind blowing across the site at that time.On still days we have the exuvia at up to 18 inches above water,after some wind about 6 inches with the emergent some 6 inches above the exuvia.But this year we have had the exuvia at only 2 inches above water and the emergent some 6 inches above it.One exuvia was found on overhanging grass where we normally find Metallica exuvia at the appropriate time.It would seem that the nymphs can plot their own emergence strategy.
Aeshna juncea. Sightings of this species seem divided between singles and notable gatherings.A curiosity of the 1995 season were unattended females cruising along sections of the Basingstoke Canal,where there was considerable woodland.
The early finish in 1994 was not understood but it was the same for A.grandis.grandis
Notable gatherings were at Thursley NNR.This reserve provides sufficient numbers of the species for observation of pairs and subsequent solo ovipositing,in sphagnum filled wet areas.Aeshna juncea seem to prefer tree-lined rides and seldom approach people unlike A.cyanea and A.mixta.
Aeshna grandis. Sightings of this species seem to be divided between patrolling males at about 100metres of Canal per territory and ovipositing females looking for a piece of wood at the waters-edge from which to oviposit.We have seen up to three females lined-up on one piece of wood.
This species also had an early finish in 1994.
Large exuvia counts are obtained on the Basingstoke Canal where it runs North from Ash Common to Frimley Lodge.The exuvia were on the west bank with their backs to the morning sun.they appear to be non-specific about what vegetation to emerge on.Choices ranged from bramble,nettle,marestail,long grass and a few reeds.Height above water-level from 20 to 60 cms.
The low recording of pairs does suggest that on our sites they do not meet over water-bodies for the purpose of mating.Perhaps like A.juncea they meet in forest rides and in treecover and then separate,the male to resume territory and the female to seek suitable sites to oviposit.We have not seen a Male interfere with an ovipositing Female.
Resting sites for A.grandis seem to be bramble bushes,in the sun and less than 30cms from the ground
Aeshna cyanea. This species which is inquisitive about people patrols both above water and in woodland.The female oviposits into mud either on banks or beneath vegetation,with a clattering of wings.
This is another species where the exuvia are not easy to find in the vegetation of ponds where they emerge.A newly refurbished pond with little vegetation gives the best chance of finding exuvia.
Further research is required to establish whether or not this species is totally dependant on smaller ponds including garden ponds for its breeding habitat.(known to like static water tanks).We have had only two exuvia from the Basingstoke Canal,both from Great Bottom Flash(which could be considered to be a large pond).
Aeshna mixta. This species seems to have an affinity with water-bodies lined with deciduous trees.It also as with A.cyanea a habit of approaching people,although not quite as confiding.
Females ovipositing are more discreet than than A.imperator or A.cyanea.Certainly they do not seem to indulge in wingbeating in waterside foliage whilst ovipositing.Out of 66 records of ovipositing ,at that date, we had observed 7 occasions where the pair oviposited --in tandem--into water using the same technique as S.striolatum.We have one record of a female ovipositing with a male in attendance,resting on vegetation about a metre away.
The exuvia are found over water,with the nymph presumably climbing direct up a reed or rush to about a metre above the water level.
Aeshna mixta in small numbers exhibit some signs of territoriality but when in large numbers over a reasonably sized lake their preoccupation is with obtaining a female and retiring to a sunlit tree of her choice,for an hour or more.The mating is not the 10 second rush of L.quadrimaculata.
Anax imperator. Sightings are divided between patrolling males and ovipositing females.Unlike A.grandis this species is highly competitive over territory and clashes are frequent.
This species can also be found in the west of the area on ponds and streams fed off the chalk springs which seems to indicate some sort of tolerance to various types of water.
Despite the size of the exuvia and the number of the species seen, its not too easy to find the exuvia,although it seems to prefer the wide leaves of yellow iris.The female is seldom seen feeding but is found busy ovipositing solo.But with one or two males waiting nearby.Blue females of considerable age are still found late in the season.
Cordulegaster boltonii. We saw more C.boltonii in one day in the mountains of West Wales than we have in any one year in the South East.In this area it is not an easily seen species with its liking for ditches as both a patrolling and ovipositing area.
Occasionally C.boltonii can be found on the Basingstoke Canal.in 1992 a female grabbed the C.aenea we were recording and departed back into the woods at Curzon Bridge.
In 1994 DRAE opened Eelmoor Marsh for an afternoons viewing,and three nymphs were found walking in shallow water,in a ditch.
Ovipositing where seen,has been into mud above the water-line,although on one occasion the mud was on the treeroots at the edge of the Canal(in one of the drained sections).
Cordulia aenea. This species seems happy to breed in both ponds and in the Basingstoke Canal.Proof of breeding being established both by emergents and exuvia.The sighting of pairs and ovipositing females is rather more difficult.Of those ovipositing--one was in tandem,three ovipositing into mud and one throwing into the water.
Emergence is into bankside vegetation,often tucked under leaves if it has been raining.
Flight tends to be low across water and particularly when they are cruising ,close into the bank,on the Basingstoke Canal.
Somatachlora metallica. Finding of pairs or ovipositing females continues to prove difficult for this species.Their habit of disappearing under shady banks or up screened inlets to water-bodies reduces the opportunity for observation.
Over open water they seem to fly both above the water and up level with the top of the trees.On the Basingstoke Canal most of the time they are level with the top of the reeds.
Exuvia have been found along the Canal,usually on bankside grass, between 6 and 12 inches long and also on short bramble shoots.
This is another wanderer and sightings have occurred well away from their known sites.
Libellula depressa. Although L.depressa can be found along the Basingstoke Canal probably emerging from the flashes,to all intents and purposes it is a creature of small pools.
The drying out of ponds has had an influence on what we have been able to record.Re-colonisation of these ponds seems to take longer than the use of new ponds.
They seem to frequent heath ponds and emerge before O.coerulescens,which use similar ponds and ditches.Their habit of sunning themselves on twigs is an aid to counting.Discovery of exuvia seems to vary from year to year,with them not always being in convenient places.
Libellula quadrimaculata. This species has small colonies along the Basingstoke Canal,although the major gatherings are in ponds and lakes.
The sub-species 'praenubila' can be found at Thursley NNR with occasionals seen at other sites.Henleypark Lake with a high count of this species has not so far yielded a 'praenubila'.
The species emerges on bankside vegetation between six inches and three feet off the ground.The exuvia are very visible,we have even watched the species emerging in the rain,without taking shelter under a leaf as does C.aenea.
The pairing can be counted in seconds,consisting of a swift grab and the female being despatched to oviposit solo.On completion she is again grabbed either by the same male or another.
Orthetrum coerulescens. The sites for this species are seepages and minor streams of which there is only one local major site at Thursley NNR.There are some minor sites in marshes and boggy areas in the local heathland.old records exist for some sites which are now barren,having been drained for farming or building.
As a result of more people being interested a few more minor sites have been found,it may be possible to discover if some of them were previously known to have the species.
Exuvia are not easy to find as they are small and usually covered with mud residue,the emergence points seem to be heather on the side of a ditch or runnel.
Orthetrum cancellatum. This species can be found at gravel pits,ponds,rivers and on the Basingstoke Canal,but quantities vary considerably.There also seem to be seasonal variations in counts.
The preference of males for sandy patches seems to be constant for all sites.Pairs make for vegetation about three feet high and move around at this level until the females are ready to oviposit,which is a solo performance.
Conservation effort in terms of clearing coarse scrub to yield areas pleasing to botanists and the more tidy-minded can have the unfortunate effect of depriving odonata of roosting sites and at worst driving them from the territory.We have found that the development of some areas and towpaths as recreational routes and the subsequent mowing of vegetation to make wider tidier paths has reduced the apparent populations of both Dragonflies and Butterflies.
Sympetrum striolatum. This species can be found on most of our sites but quantities vary.Outstanding gatherings have occurred at Eversley Gravel Pits(before it was fenced),Thursley NNR,Bramshill,Wellington Country Park and Frensham.Some sections of the Basingstoke Canal had large gatherings but we have not recorded a major gathering since boat-traffic commenced.
The late season habit of quantities of females to lurk in glades,in the woods,a considerable way from water has been noted.As has the relaxed end of season for the males perched in the sun around small ponds.
Lakeside has begun to produce large emergences,since the new ponds have come into operation,but it seems there is a large dispersal from this site as many fewer adults are seen.
Sympetrum Sanguineum. The population at any one site of this species seems to be very variable.On the Basingstoke Canal they seem to move from cluster of reeds to another cluster on an irregular basis,sometimes within the same 1 kilometre square and sometimes not.Confuses the recording.
This was another species that had an early finish to the local season in 1994.
The preferred habitat seems to be compact reed-beds and any form of management seems to accelerate the departure of this species.
The willingness of the male to attack any passing odonata species crossing its territory is a useful way of locating their changing sites.
The larger gatherings were at Langhams(Runnymede),Boldermere,Epsom Stew Ponds,Henleypark,Englemere and Brook Pond
Sympetrum danae. The preference of this species for heathland means that any reduction in visits to Thursley NNR will considerably reduce the number of this species seen in a season.
Our experience with Kiln Pond ,on Chobham Common,which has a very variable water level shows that a large gathering can occur in one year but the next will be an apparent disaster.
This species suffers from predation by ducks as their habit of lining up as pairs on low vegetation at the waters-edge means they are an easily seized mouthful for the ducks.
Emergence seems to be on grass and other low vegetation in shallow water making location of exuvia difficult.Emergents are counted by flushing them from suitable sites.
Leucorrhinia dubia. Thursley NNR is the last remaining southern site for this species,now Wisley has failed.The population at Thursley has been weakening for some time and it is possible to miss seeing the species during the season.There is some dispute as to where any residual population may be located,as the normal place was one specific pond but they have been observed emerging out of the centre ditch and earlier observers found them in different ponds.
Two new ponds have been provided,it remains to be seen if the population can be saved,unless the increase in average summer temperature becomes too much for this more northerly species.