Blue-eyed Hawker (Southern Migrant Hawker) Aeshna affinis

The first Lincolnshire records Alkborough Flats August 2019

Neil Drinkall, Graham Catley and David Hursthouse

Formed from September 2006 when the Humber sea wall was breached for the first time, the 440 hectares of Alkborough Flats Managed Realignment site has developed rapidly over the ensuing 13 years. Initially arable farmland the eastern part of the site was subjected to regular tidal inundation and siltation quickly built up the level of the site and saltmarsh and latterly phragmites spread quickly over the shallow lagoons and mudflats covering almost 90% of the former mudflats by late 2018. At the base of the Trent embankment a drainage ditch expanded from 2010 onwards as water levels rose in the adjacent field and the ditch quickly became overrun with rush and then phragmites the latter species becoming dominant from 2016 onwards. The images below show the Trent Flash, ditch complex, in 2008, 2013 and 2019 respectively.

Regular wildlife surveys of the site took place from 2007 onwards and during this period a total of 20 species of odonata were recorded including Lesser Emperor Anax perthenope, Small Red-eyed Damselfly Erythromma viridulum, Common Hawker Aeshna juncea and Black Darter Sympetrum danae.

On the afternoon of August 3rd Neil Drinkall was walking the Trent bank searching for dragonflies when at approximately 13:55 he came across a small aeshna, in size similar to a Migrant Hawker, patrolling low along the edge of the Trent Flash in a small area of open water on the edge of the reedbed where some soft rush was dominant. He was struck by the bright blue eyes and the brightness of the blue markings on the thorax and abdomen that immediately suggested male Southern Migrant Hawker Aeshna affinis a species he had not seen before but as there had been two males at Spurn in recent days there were good images on the internet which appeared identical with the individual he was watching. With a fresh wind blowing the dragonfly was keeping low but it proved impossible to photograph in flight. Fortunately, it landed in the reeds at the back of the small opening and ND was able to obtain some confirmatory images of this new species for the Lincolnshire odonata. ND watched the Blue-eyed (Southern Migrant) Hawker on and off until about 15:30 but by the time GPC and DH arrived at c 17:00hrs it had been lost and with thick cloud covering the sun it did not reappear that evening but fortuitously a male Banded Demoiselle Calopteryx splendens, landed in the same location and was a second new species for the site odonata list in one afternoon.

The following day ND, GPC and DH were again on site and with extended sunny periods and warm temperatures the day was looking good for dragonflies with several Brown Hawkers, Emperors and Common and Ruddy darters being seen en route to the Trent Flash. It was quite breezy with the wind blowing from the south along the Trent Flash. A search of the original location revealed that a male Brown Hawker had taken up residence and there was no sign of the Southern Migrant Hawker. GPC and DH then set off to walk north along the Trent embankment searching for other suitable habitat and 350m north of the original location GPC saw the male Southern Migrant Hawker patrolling on the western side of the Trent Flash in a very similar site to the original area albeit with no actual open water. This location was again dominated by soft rush with some Greater Reedmace on the western side of the phragmites beds in the old Trent Flash and adjacent ditch. The male Southern Migrant Hawker was watched from 10:15 to 11:37 constantly hawking over the same restricted area on the edge of the reedbed never going more than 4m up and usually hunting within 1m of the top of the rush and level with the tops of the reeds. It was never seen to land but occasionally chased off Ruddy Darters. At 11:35 the male suddenly shot off upwards and seemed to attack something in the air above the reedbed falling into the grass on the adjacent embankment. A quick look with binoculars revealed that what had actually happened was the male had grabbed a female in the air and they were now in tandem on the ground. Before any photos could be taken, they flew up and landed in the middle of the reedbed but fortunately they them flew back into the short rush area and a few images were obtained before they again flew off over the reeds and were not seen again. It seemed utterly amazing that this vagrant first for the county had somehow found a female flying over the same reedbed but clearly that is what had happened and this was now the first female for the county as well as the first male. Less suitable weather dominated the ensuing week but the areas of the original sightings were checked a few times with no further sightings of either individual.

A series of flight images were taken of the male a selection of which are presented below along with shots of the pair in tandem. All images at © Graham Catley