Monday, 2 March 2009

Dragonfly Report for 2008

At the end of last years report I hoped for a better recording season in 2008. Well, it was not to be unfortunately, with cool and often rainy conditions dominating the summer; not the most auspicious of starts for the Atlas Project [both county and national]. Despite this however there were a few interesting observations and happenings of note.
The first recorded odonata of the year, on 2nd May, was of a female Large Red Damselfly Pyrrhosoma nymphula f. fulvipes by the River Ray in Swindon.
The 4th May saw the launch of the Cotswold Water Park [CWP] Dragonfly Atlas Project at Lower Moor Farm [Wilts Wildlife Trust Reserve]. This project is to run in parallel with the county and national atlas projects. Kat Parkes [Conservation Officer of the British Dragonfly Society] came along to lend her support and present an overview of the national atlas project. Gareth Harris [CWP Society's Biodiversity Officer] and Ingrid Twissell [Gloucestershire Recorder] also gave presentations. We also gained several new recorders who pledged to adopt tetrads in CWP!
After lunch we had a walk around Mallard Lake during which we saw several Large Reds but also some early Common Blue Damselflies Enallagma cyathigerum including a pre-flight emergent and exuviae.
Over the next few days several more damselfly species began to appear. Also the first dragonfly, a teneral Broad-bodied Chaser Libellula depressa, was found by Damian Pinguey at Somerford Common on the 9th. On the same day I found an exuvia of a Downy Emerald Cordulia aenea dragonfly at Lower Moor Farm; first proof of breeding for the site!
Downy Emerald (Cordulia aenea) exuvia.
This is a target species within the revised Wiltshire Biodiversity Action Plan [WBAP] and is part of the Habitat Action Plan [HAP] for Standing Open Water [SOW] - sorry about all the headings and acronyms, a necessary evil these days...It is intended to revisit all existing and historical sites for Downy Emerald by the end of the 2009 season to establish current presence or absence and [if possible] proof of breeding. So 2008 went a good way to fulfilling these targets with proof of breeding confirmed at Swillbrook Lakes in CWP as well as Lower Moor. The strongest colony is at the National Trusts property of Stourhead in SW Wilts and during a visit there on 9th June I counted at least 26 individuals, including mating and ovipositing. In addition I collected 8 exuviae off Hosta leaves at one of the pond margins with yet more present out of reach. Mixed in with these were several
Four-spotted Chaser Libellula quadrimaculata exuviae. Although C. aenea was absent at two other sites visited it may have been as a result of visiting in the 'off' year [ sites where only one colonisation event ever took place can result in adults only being present every other year because of the 2 year life cycle of this species]. They were also reported from Bentley Woods ponds, east of Salisbury, by several observers.
Scarce Chaser Libellula fulva continued to expand its range, being discovered by a Hampshire enthusiast visiting the county [Julie Thomas] on the turning ponds of the Caen Hill locks of the Kennet and Avon Canal at Devizes. There were at least 20 - all very fresh teneral individuals and, given that the main breeding site, the River Bristol Avon, is some distance away, is highly suggestive of local breeding. No exuviae were found but it's not the easiest of sites to work! Hopefully proof will be found over the next few years. This news reached both local and national press and the latter managed to get the wrong end of the stick stating that this discovery was new for Britain!! Oh well, at least dragonflies reached the Times;o)
On the downside L. fulva wasn't seen at the Semington bypass ponds after my surprise discovery of them there in 2007. Perhaps it was just a one off because of the exceptional weather of 2006 - only time will tell.
Beautiful Demoiselle Calopteryx virgo was re-recorded at its new locations as well as the more traditional sites, giving the impression that it is consolidating its expansion within the county. Rob Turner [Wilts Bird Recorder] reported it again from woodland rides on the edge of Salisbury Plain. He also saw several other species on the Plain - mostly associated with flooded tank tracks, perhaps one of the few positive by-products of the wet summer!
Beautiful Demoiselle (Calopteryx virgo).
After the excitement of breeding records in 2007 it was a disappointment not to have any records, breeding or otherwise, of Lesser Emperor Anax parthenope. Another species we will have to keep our fingers crossed for in this fluctuating 'climate change' weather. There were also no records of Keeled Skimmer Orthetrum coerulescens from its site near Shearwater Lake, Longleat Estate. Its presence there is tenuous anyway but it is hoped this is just a temporary set back. Better news is that Small Red-eyed Damselfly Erythromma viridulum is still going strong[ish] at the Great Western Hospital pond in Swindon, with both mating and ovipositing being observed.
Forest Enterprise has carried out conservation work in Savernake Forest, near Marlborough with the intention of increasing its biodiversity. The work has included clearance/dredging of at least 10 ponds which were previously silted up or filled in, and the clear felling of trees around them to let the sunlight in. Ian McColl has taken on board the task of monitoring these ponds to see how the odonata respond to this work. Already the expected pioneering species such as Broad-bodied Chaser and Azure Damselfly Coenagrion puella have moved in quickly and in numbers!
Broad-bodied Chaser (Libellula depressa)
Less expected was a surprise visit by one or maybe two
Black Darter Sympetrum danae dragonflies on 22nd-24th August. With the nearest known breeding sites beeing the New Forest this is probably a wanderer. This species is well known for it's migratory movements both within and from outside the UK.
The last species to be recorded were on the 12th October when I noted Brown Hawker Aeshna grandis, Southern Hawker Aeshna cyanea, Migrant Hawker Aeshna mixta and Common Darter Sympetrum sanguineum dragonflies at Lower Moor Farm. Some of the latter were mating and ovipositing. Most amazing though were the presence, still, of at least 6 Common Blue Damselflies which meant they had been present at this site for 6 months and 8 days!!
A series of hard frosts then put paid to any more sightings [unless you know different of course!]
Many thanks for all the hard work put in by our band of observers in what were difficult conditions this year. Also, if anyone is reading this who doesn't currently record but might like to then please let me know.