Saturday 30 January 2021

Oxon Dragonflies & Damselflies in 2020 - a review


Highlights
While 2020 was a difficult year for recorders, it was an exceptional one for Odonata in the County. It was probably the best year ever, and was certainly the best in the last ten years.

Key highlights were:
  • Southern Migrant Hawker - first records for the County.
  • Willow Emerald Damselfly - after one isolated record in 2019, in 2020 there were sightings from three sites, with breeding confirmed at one. Also the first photos ever.
  • Scarce Blue-tailed Damselfly - first records for about 20 years.
  • Clubtail - unprecedented numbers of both emergents and adults recorded.
  • Small Red-eyed Damselfly - explosion in distribution across the County.
  • Lesser Emperor - first record since 2011, and the first female ever recorded in the County.
  • Red-veined Darter - first record since 2012.
  • Keeled Skimmer - the first report away from its Cothill reserves stronghold in about 20 years
  • A total of 30 species seen - at least five more than normal.
Season narrative
With the favourable spring weather, the season got off to a good start with four species seen in April, including the first of an unprecedented number of Clubtails along both banks of the River Thames, generally downstream from Abingdon. These included records of multiple emergences from the traditional site of Goring Railway Bridge as well as sightings of adults in at least one garden.  Alan Dawson did particularly well and found at least eight adults in the Cholsey area alone! 

Mature male Clubtail ©  David Hastings

In mid June, Brian Stone, an out of county recorder, found a small breeding colony of Scarce Blue-tailed Damselflies at a surprising new site - a storm water pool at Longford Park, Banbury.  This was the first record of this species for about twenty years. It took a few weeks for the news of this amazing find to get out but fortunately their flight season is reasonably long. Many of the county's keenest Odonata recorders made the trek north to Banbury and were rewarded with good views (although there was some confusion with the more numerous Blue-tailed Damselflies also present!).

 Scarce Blue-tailed Damselfly - aurantiaca form of the female © Stephen Burch

Also from this site, Toby Holmes found of a Keeled Skimmer - the first seen away from its Cothill stronghold in about 10 years! Apparently this species does tend to wander, especially in hot summers, although where it came from is unclear - there are no nearby sites in the other counties bordering Oxfordshire. 

Keeled Skimmer (c) Toby Holmes

Another major discovery in mid June was by Geoff Wyatt who found an immature male Southern Migrant Hawker on the west side of RPSB Otmoor.  This was a county first! A mini twitch then followed and most but not all obtained good views and photos of this new and charismatic addition to the county dragonfly scene. Several immatures were then seen at the same location, so it is likely that this species had bred there undetected for the first time in 2019. 

Immature male Southern Migrant Hawker ©  Geoff Wyatt. First Oxon photo!

Subsequently small numbers of adults were seen at various locations across this reserve, although they remained elusive throughout. It is hoped that this charismatic species will be easier to find in 2021.

Mature male Southern Migrant Hawker ©  Geoff Wyatt

Adrian Parr has kindly provided this distribution map shows the locations of all records of Southern Migrant Hawker, updated to include 2020 sightings. Otmoor is shown in red - one of most "inland" of all current records! 


Southern Migrant Hawker distribution map showing the location of the Otmoor records in red (courtesy Adrian Parr) 

In mid season, the reserves around Cothill again produced good numbers of sightings and photos of the three special species that are found there:

Male Small Red Damselfly © David Hastings

Keeled Skimmer © Stephen Burch [focus stacked]

Southern Damselfly © David Hastings

After being confined to a handful of locations in the County previously, another mid-season highlight was the explosion of Small Red-eyed Damselflies into new sites all across the county. The traditional site of Faringdon Folly Park Pond probably had the highest numbers. But a pond on the west side of Otmoor also had numbers into double figures, found by observers searching, often in vain, for Southern Migrant Hawkers. Additionally, there were reports from many other sites widely distributed across the County, including, for the first time, along the River Thames. 

The main highlight in August was the establishment of Willow Emerald Damselfly as a breeding species in the County, after a single unconfirmed and isolated record from Wytham Woods in 2019. 

The first confirmed record and photo was by our esteemed County Bird Recorder, Ian Lewington, from Radley Lakes on 11 August:

Willow Emerald Damselfly (c) Ian Lewington [first Oxon photo of this species]

Shortly afterwards, further records came from Otmoor where small numbers of both males and females were subsequently found.

Willow Emerald [focus stacked] © Stephen Burch

Nicola Devine then found larger numbers into double figures and was able to confirm breeding at the Trap Grounds Nature Reserve, Oxford. The regularity of sightings from this site attracted interest from both within and outside the County. 

Willow Emeralds ovipositing © Nicola Devine

There were then even more highlights towards the end of the season, although both were single observer records only.  The first sighting of a female Lesser Emperor in the County was by Brian Walker from a lake between Drayton and Sutton Courtenay. However this came to light only belatedly from his excellent photo:  

Female Lesser Emperor eating a wasp (c) Brian Walker

Then, in September, Wayne Bull found a Red-veined Darter at Radley Lakes, at a very similar location to the last one he found there in 2012! There was unfortunately no sign of it subsequently in what was a relatively poor year from this species nationally. 

Red-veined Darter (c) Wayne Bull


The last record of this amazing season was of a Common Darter at Otmoor on 22 November by Pete Roby (see below).