Nature Notes

Wharfedale Naturalists Society

In the first week of June, while doing a bird survey below Harewood on a sunny morning, hundreds of Banded Demoiselles, our largest damselfly, crowded the riverside grass along the Wharfe.

However, after that several weeks of wet and gloomy weather set in and around our garden ponds not a damselfly was to be seen until a few days of sunshine in the final week at last produced numbers of both Large Red and Azure Damselflies (pictured is a brilliant blue male Azure), much later than I had expected.

Damselfly larvae usually emerge from the water in the early morning and need warm dry conditions for their bodies to harden and take on colour and their wings to expand.

Their vulnerability to predation was emphasised by a morning when, despite overnight rain, several larvae had climbed up the spiky leaves of water soldiers and emerged from their skins. I watched a hunting wasp settle on one helpless individual, bite off the wings and efficiently roll up the long, almost colourless body into a ball before flying off with it.

At the end of June, our ponds usually produce much larger Southern Hawker Dragonflies but, at the time of writing in the first week of July, I am still waiting for the first of these. Like their damselfly relatives they need warm, dry mornings to emerge and then to survive.

I fear that the difficulties faced by damsel and dragonflies as a result of our increasingly unpredictable weather are symptomatic of similar problems confronted by other insect species in addition to those of habitat loss and pesticide pollution. Butterfly and moth numbers certainly seem to be down.

There is inevitably a knock-on effect on creatures which rely on a summer glut of insects to feed themselves and their offspring. Concern has been expressed nationally over the fate of our swifts, present for only three months in which to raise their young.

The cause of the torrential rain experienced in mid-June over several weeks was apparently a meander in the jet stream that became stuck over eastern England. It usually blows strongly from west to east carrying our weather with it, driven by the big temperature difference between the Arctic and Atlantic Oceans. With the exceptional warming taking place in the Arctic happening twice as fast as predicted by climate experts, this temperature difference is being eroded and the jet stream is becoming weaker and more likely to wander.

Polar bears are not the only victims of the rapidly melting arctic ice. Our weather and our wildlife are being hit too.

wharfedale-nats.org.uk