Monday, 1 June 2009

The return of the Red-veined Darters

Heysham Obs
A bit too windy yesterday on the model boat pond and we needed to be alerted by findings yesterday at Fleetwood Marsh nature reserve to check in this morning's calmer conditions

Middleton IE model boat pond
Red-veined Darter - The first was located at 1030hrs and by 1130 there were definitely 3 males and probably four in view, scattered all over the model boat pond. 3 were seen in the afternoon with instructive comparison with Common, including a perched individual showing pale centred pterostigma (dark in Common, visible through 'scope at 50 metres!)
Common Darter - Up to 5 in the afternoon, including two very red males. Be careful before you jump to conclusions re-Red-veined. I think these are the earliest ever mature Common Darter for here and are surely migrants (which need checking for Vagrant???)

One of the easiest ways to start the process of separating Common from Red-veined (hundreds of hours put in observing the latter over water) is that Red-veined
1) dont gain height whilst hovering and usually stay close to the water surface in flight
2) change direction very suddenly and acutely, again without gaining height
3) usually spend longer over the water than Common

The red venations are often only clearly visible when the insect is hovering and facing the observer with the sun behind the observer = fortunately most of the day in the model boat pond lower car park

The vexing question is the origin of these insects. The smart money was on no further sightings of locally-born individuals after last year's single observation...but there was hardly any suitable flying weather last year! Therefore we need to wait and both Fleetwood and Middleton IE have breeding history and if there are none reported anywhere else in the north............ The Painted Lady influx obviously does suggest suitable arrival conditions from southern Europe and the following was 'lifted' from the BDS site:

"There has been a significant influx of Red-veined Darter into southern England during the last week of May, with records currently from at least seven sites (no doubt they have been accompanying the Painted Lady butterflies!). Observers are encouraged to be on the lookout for the species".

Surprisingly, no sign of any Black-tailed Skimmer yet

Remainder of Middleton IE ponds
A quick search in the afternoon again revealed no Emperor or Black-tailed Skimmer
Clouded Yellow - one sauntering around 'off passage' between the model boat and no swimming ponds
4-spotted Chaser - c80

North wall
Black Guillemot reported in the harbourmouth

Heysham NR
First Emperor dragonfly of the year by the gate

As there were Red-veined Darters on the Fleetwood marsh nature reserve pond yesterday (including an ovipositing female), worth checking any shallow pools with bare edges e.g. Freeman's Pool (but beware early mature Common).