Saturday, 1 August 2020

Hull Dragons 2020: July summary

The first three weeks of July had very changeable weather, with plenty of overcast, muggy weather and some showers. Sunny spells were few, short and far between until the last week, where we enjoyed a few days of warmer, consistent sunny weather. 

Odonata highlights
Records were initially slow coming in July, but overall the month had a total of 113 records from 13 species have been submitted by 7 recorders from 20 km2, a few more than in June. As expected, the Blue-tailed Damselfly tops the list in terms of numbers of records, followed by the Emperor Dragonfly, and the Common Darter, with the same number of records. The surprise is that the Brown Hawker is tied 4th with the Azure Damselfly, with 11 records, more than were recorded during the whole of last year. The year total so far stands at 18 species.

First records of the year
  • Ruddy Darter, 11th July
  • Common Darter 11th July
  • Emerald 19th July
  • Brown Hawker 19th July.
  • Migrant Hawker, 24th July
  • Small Red Eyed Damselfly, 25th July
Emperor behaviour
Emperors seem to be having a good year at the recording area. I've had a great time watching the behavioural differences between males and females. Males are a very showy dragonfly, 'presiding' over their territory, a pond, lake or a stretch of ditch, flying powerfully, over the open water, occasionally hovering on a spot, rising to catch an insect or flying over the banks, even checking birds flying past (I watched a brief Swallow-Emperor face off, both flying away!). They are always pulled back to the water, unlike other hawkers. At some point, they stop their hunting and patrolling to bask or finish a meal, usually on marginal vegetation facing the sun, but also rarely on the ground.
An emperor resting on the ground is an unusual sight. It is likely that it was sheltering from the wind.
Female's behaviour is completely different. They approach the water stealthily, flying low and near the shore, searching for oviposition locations (sticks or floating vegetation). They can be as colourful as males, as the following photo shows. If a male discovers a female, she will try and fly higher than him, curling her abdomen down in a signal of rejection. I've never witnessed a copulation in this species.
Ovipositing Emperor at Foredyke Green Pond. 
Male Emperor at Pickering Park. 
Pickering Park lake is large enough for several Emperors, but the northern side of the pond seems to be the most attractive and it is a place that year after year allows me to see males chasing and clashing for territory. In this case, one of the males landed in the vegetation to rest, while the other one carried on the patrolling. Ovipositing was also observed in the same area of the park. Ovipositing in July was also observed at Noddle Hill Lake, and Foredyke Green Pond.

Watching Brown Hawkers
Brown Hawkers are also having a good year . Four were seen hunting along rides and paths at Noddle Hill nature reserve. At the Beverley and Barmston drain near Beresford Avenue, I watched one for 20 minutes as it hunted repeatedly flying up and down the drain. It took advantage of the light breeze to glide back, then flew powerfully upwind, checking every passing insect, releasing some that were not of his taste. I was slightly amused as the hawker checked every passing creeping thistle seed (just like me!), and there were plenty floating in the breeze. I was hoping the Brown Hawker will have a rest at some point, but it didn't. Its territory-  and it was a male - was 20-30 meters along drain, with plenty of emergent and floating vegetation and a hedgerow on one side by the allotments. It flew high over the water, maybe over 1 m high, and then occasionally charged against the marginal vegetation, possibly to dislodge resting insects. Although I've got no photo opportunities so far, I enjoyed watching the species behaviour from a great vantage point.

Species gallery
Four-spotted chaser at Foredyke Green Pond.
Teneral Southern Hawker at Setting Dyke.
An Azure Damselfly rejects another's advance.
Blue-tailed Damselfly.
Teneral Common Darter at Pickering Park.
Common Darter at Midmeredale Pond.
Mating Blue-tailed damselflies at Pickering Park (note that the female is the same colour as the male, they are known as androchrome females).
Emerald, one of two males at Noddle Hill NR.
Small Red-eyed Damselfly at Paull Holme Strays. A mating pair was observed at Pickering Park.
A record shot of my first Migrant Hawker this year.

No comments: