Highlights of the 2021 season

With the days lengthening and spring just around the corner, it seems timely to look back at last year's season:

Highlights

• The poor spring and early summer weather made for a late start to the season and numbers throughout the season appeared to be down compared with the exceptional 2020.
• Following the first records in 2020, Southern Migrant Hawkers were again found on Otmoor but numbers were lower than last year and it was even more elusive.
• Following the first confirmed records from three sites in 2020, Willow Emerald Damselfly was reported from the same sites in 2021. Three new sites close to the River Thames in the south-east of the county were also found.
• The Small Red Damselfly population at the Cothill reserves is apparently low but stable. However for the first time ever in the county, singles were seen well away from these reserves, at Radley Lakes and near Cholsey (about 20km away).
• Scarce Blue-tailed Damselflies were again seen at Longford Park, Banbury and a new site was discovered at a stormwater pond in Didcot.
• Keeled Skimmers were reported from two new sites away from its Cothill stronghold, at Sydlings Copse BBOWT and the Lye Valley, Oxford where breeding was suspected. 
• Only a small number of records of Variable Damselfly were received, all from the Barton Fields/Radley Lakes area.
• Club-tail had a more typical year than its exceptional 2020 showing, but there were still several records from its Goring stronghold as well as an unusual downstream sighting at Wargrave. There are normally very few reports from upstream of Oxford but this year there was a remarkable four from the Appleton area and one at Newbridge.

Summary of season

With the unfavourable spring weather, the season got off to a slow start with very few records in April. Overall, emergences seemed to be later and numbers appeared to be down compared with the exceptional 2020. This trend was reflected in the daily counts of Southern Hawker exuviae, made by Deborah Dunn, at a small, shady garden pond in Steeple Aston. This year the total emergences recorded was almost 30% down on the 2020 figure and the mean emergence date was 14 days later, even for this mid-season species. 

Following their exceptional showing last year, records of Common Club-tail returned to more typical numbers, although there were still several records from its Goring stronghold as well as an unusual downstream sighting of one that landed on a paddle board at Wargrave! There are normally very few reports from upstream of Oxford but this year there was a remarkable four from the Appleton area and one at Newbridge. 

Only a small number of records of Variable Damselfly were received, all from the Barton Fields/Radley Lakes area, with a maximum count of 10+. 

Following their discovery last year, Scarce Blue-tailed Damselflies, Wayne Bull again found them at the stormwater pond on Longford Park, Banbury. An entirely new site was discovered by Ian Lewington well away from here in Didcot, at another stormwater pond. Following the first records last year, Southern Migrant Hawker were again located on Otmoor by Geoff Wyatt and others as both immatures and adults, but numbers appeared to be down with sightings few and far between. 

Results from the BBOWT transect surveys showed that Keeled Skimmer is doing well at its Cothill reserves stronghold. It was also seen at the new sites of Sydlings Copse BBOWT and the Lye Valley, Oxford where breeding was suspected. Southern Damselfly was also found in good numbers at the Cothill reserves, especially at Parsonage Moor, where a remarkable 164 were counted (the highest total ever recorded at this site) during a single transect survey visit.  

Also at Parsonage Moor, the maximum sightings per visit of the scarcer Small Red Damselfly increased compared with last year to a value comparable with the numbers found between 2013 and 2017 (average of 9). For the first time ever in the county, singles were seen well away from these reserves, at Radley Lakes (about 6km from Cothill) and at a stormwater pond near Cholsey (about 20km away).

The more abundant Small Red-eyed Damselfly continued its spread into new sites, with the best this year being a stormwater pond at Grove, where the peak count was over 100. Fewer were found at Faringdon Folly Park Pond, which has previously been the best site in the county, probably due to the removal of many of the algal mats this species favours.

Following their arrival last year, Willow Emerald Damselfly were relocated at the same three sites, and were also noted at three new sites close to the River Thames in the south east of the county. The last record was of a Common Darter at Otmoor on 22 November. Over the year, 29 species were seen in Oxfordshire.  

Clubtail at Goring © Stephen Burch

Common Darter at Grove Meadows  © Stephen Burch

Migrant Hawker at Grove Meadows © Stephen Burch

Southern Hawker at Shillingford © Stephen Burch

Small Red-eyed Damselfly at Grove Meadows  © Stephen Burch

Willow Emerald Damselfly at Shillingford © Stephen Burch