Wednesday, 20 September 2017
Thursday, 14 September 2017
Sunday, 10 September 2017
Oxon Clubtail Count 2017: An initial summary
First of all many thanks to all those of you that participated in the BDS organised 2017 Common Clubtail count in Oxon and were kind enough to share your records with me.
The BDS is apparently analysing all the results sent to them, but it isn't clear when the results will be available, so this initial summary of Oxon records received and published on my Clubtail Count webpage may be of interest to those who participated, and others.
If anyone has any further records from Oxon, that they reported to the BDS, but do not appear on my webpage, please let me know.
Overall, it is pretty clear that the survey confirmed how elusive this species is in the county. Of those dragonflies that regularly breed in Oxon, Clubtails must be by far the most difficult to see, especially in adult form.
After some success on my first weekend, I for one found the count hard going (for further info, see my personal account at the end of this report), and I suspect many others had negative visits to their allotted squares, about which I have little information.
For the count, I received only 11 separate reports. The first of these was of a newly emerged adult at Abindon Lock on the early date of 29 April (Bob Eeles), while the last, of an exuvia on the Oxford side of the Thames at Sonning (Nick Percival) was only just over a month later on 1 June.
In all, there were reports of only 9 adults (by which I mean any flying insect, including those emerging and immatures recently emerged). As several of these were from the well known Goring Railway bridge site, adults were found in only 5 different 1km squares on the Oxon side of the river - a very disappointing total. Moreover, of these 5 squares, only 1 was upstream of Oxford (at Tadpole Bridge - found by my wife on 14 May!). Formerly, going back several years, Clubtails were regularly reported from the upper Thames. No longer, it seems.
Exuviae were generally slightly easier to find, with the total reported being 26, but again, with the great majority of these coming from Goring Railway Bridge, these came from only 5 different 1km squares. All were found on the lowest stretch of the Thames in the county - from Goring to Sonning.
It is interesting that all exuviae were reported to be on man-made structures such as wooden posts, and the river wall under the railway bridge south of Goring. This may be due to the fact that exuviae are much easier to see on these structures rather than on normal riverside vegetation, but could it be that the larvae actually prefer them?
Finally, I thought my own account of the survey might be of interest to other counters, so here goes (keeping it reasonably brief).
My count started remarkably well on the weekend of 13/14 May. On the Saturday, a walk downstream from Goring village produced my first exuviae record (2 on a wooden post) within about 100m of reaching the river bank. Thereafter I found 3 more in the next 1km square, and on reaching the famous railway bridge, I met another observer (Stephen Darlington) who had found 6 on the river wall, of which I saw 4. No adults though.
The next day, my wife and I mounted a two car "expedition" to cover the 5 mile stretch of river between Tadpole Bridge and Radcot. Within 100-200m of the start, my wife spotted a dragonfly which, given the date and location could only have been one thing! Sure enough it was a newly emerged Clubtail in vegetation just beside the path. However it was windy, and it didn't hang around - quickly disappearing over some shrubs towards the river. Thereafter we carefully scanned every man made object in the river (posts, walls etc) all the way to Radcot, without finding any exuviae or further adults.
Over the next few weeks, I made several further visits to that stretch of the Thames, from both the Radcot and Tadpole Bridge directions, but saw no further sign of adults or exuviae. We also tried, on a blustery Sunday morning, the river north Days Lock without success.
My final attempt was is mid June when I revisited the river south from Goring to the railway bridge in an attempt to find mature adults returned to the river to breed. Despite the apparently ideal conditions (on a stunningly hot day), there was no sign of anything Clubtail like!
During these mostly unsuccessful surveys, I did however find various other Odonata species. Banded Demoiselle were of course almost omnipresent in every 1km square, and I was surprised how common Red-eyed Damsels were on the river margins. There were also good numbers of Emperors to be found patrolling up & down their territories. From Goring south to the railway bridge also produced a small number of the much more localised White-legged Damselfly, on my second, mid June visit.
The BDS is apparently analysing all the results sent to them, but it isn't clear when the results will be available, so this initial summary of Oxon records received and published on my Clubtail Count webpage may be of interest to those who participated, and others.
If anyone has any further records from Oxon, that they reported to the BDS, but do not appear on my webpage, please let me know.
Overall, it is pretty clear that the survey confirmed how elusive this species is in the county. Of those dragonflies that regularly breed in Oxon, Clubtails must be by far the most difficult to see, especially in adult form.
After some success on my first weekend, I for one found the count hard going (for further info, see my personal account at the end of this report), and I suspect many others had negative visits to their allotted squares, about which I have little information.
For the count, I received only 11 separate reports. The first of these was of a newly emerged adult at Abindon Lock on the early date of 29 April (Bob Eeles), while the last, of an exuvia on the Oxford side of the Thames at Sonning (Nick Percival) was only just over a month later on 1 June.
In all, there were reports of only 9 adults (by which I mean any flying insect, including those emerging and immatures recently emerged). As several of these were from the well known Goring Railway bridge site, adults were found in only 5 different 1km squares on the Oxon side of the river - a very disappointing total. Moreover, of these 5 squares, only 1 was upstream of Oxford (at Tadpole Bridge - found by my wife on 14 May!). Formerly, going back several years, Clubtails were regularly reported from the upper Thames. No longer, it seems.
Newly emerged adult at Tadpole Bridge on 14 May (c) Stephen Burch
Exuviae were generally slightly easier to find, with the total reported being 26, but again, with the great majority of these coming from Goring Railway Bridge, these came from only 5 different 1km squares. All were found on the lowest stretch of the Thames in the county - from Goring to Sonning.
It is interesting that all exuviae were reported to be on man-made structures such as wooden posts, and the river wall under the railway bridge south of Goring. This may be due to the fact that exuviae are much easier to see on these structures rather than on normal riverside vegetation, but could it be that the larvae actually prefer them?
Clubtail exuvia at Goring (not the railway bridge) on 13 May (c) Stephen Burch
Finally, I thought my own account of the survey might be of interest to other counters, so here goes (keeping it reasonably brief).
My count started remarkably well on the weekend of 13/14 May. On the Saturday, a walk downstream from Goring village produced my first exuviae record (2 on a wooden post) within about 100m of reaching the river bank. Thereafter I found 3 more in the next 1km square, and on reaching the famous railway bridge, I met another observer (Stephen Darlington) who had found 6 on the river wall, of which I saw 4. No adults though.
The next day, my wife and I mounted a two car "expedition" to cover the 5 mile stretch of river between Tadpole Bridge and Radcot. Within 100-200m of the start, my wife spotted a dragonfly which, given the date and location could only have been one thing! Sure enough it was a newly emerged Clubtail in vegetation just beside the path. However it was windy, and it didn't hang around - quickly disappearing over some shrubs towards the river. Thereafter we carefully scanned every man made object in the river (posts, walls etc) all the way to Radcot, without finding any exuviae or further adults.
Over the next few weeks, I made several further visits to that stretch of the Thames, from both the Radcot and Tadpole Bridge directions, but saw no further sign of adults or exuviae. We also tried, on a blustery Sunday morning, the river north Days Lock without success.
My final attempt was is mid June when I revisited the river south from Goring to the railway bridge in an attempt to find mature adults returned to the river to breed. Despite the apparently ideal conditions (on a stunningly hot day), there was no sign of anything Clubtail like!
During these mostly unsuccessful surveys, I did however find various other Odonata species. Banded Demoiselle were of course almost omnipresent in every 1km square, and I was surprised how common Red-eyed Damsels were on the river margins. There were also good numbers of Emperors to be found patrolling up & down their territories. From Goring south to the railway bridge also produced a small number of the much more localised White-legged Damselfly, on my second, mid June visit.
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