Insect Surveying – by Dick Alderson

Having updated his reports with last season’s surveying data, Dick Alderson, along with the rest of our team of insect surveyors, is ready to swing back into action next month.  Dick kindly agreed to write a blog post about the excellent work that he and the rest of our dedicated team do throughout the summer months at Loch Leven.  Dick’s full reports can be viewed online on the Publications page of our website, and updates will feature on the blog during the course of the season.

Surveyors in action

Surveyors in action

Surveyors in action at Mary's Knowe

Surveyors in action at Mary’s Knowe

Insect Surveying at Loch Leven NNR

After a winter of analysing data and producing charts of how populations have changed, it will soon be the time of year when active insect surveying gets started again. It all began back in 2008 when Craig Nisbet encouraged a group of enthusiastic amateurs to start monitoring the insects on selected areas of the Loch Leven NNR. He designated the transects to be walked and did some basic training in identification skills; and the transects, with a few changes and one addition, have been monitored ever since. Three groups of insects are counted, Bumblebees; Butterflies; and Damsel and Dragonflies. Counting the first two starts in April but the surveying for Damsel and Dragonflies is delayed until May when they start to emerge from their water bound nymphal stages.

As summer advances the ponds will change from this (Old Railway Pond in April)...

As summer advances the ponds will change from this (Old Railway Pond in April)…

...to this (same pond in July).  It is then that the darkly camouflaged dragonfly and damselfly nymphs emerge as brightly coloured adults.

…to this (same pond in July). It is then that the darkly camouflaged dragonfly and damselfly nymphs emerge as brightly coloured adults.

The Common Darter, an ambush predator of aquatic life...

The Common Darter, an ambush predator of aquatic life…

...changes to become this expert of aerial hunting.

…changes to become this expert of aerial hunting.

Counts are made on a designated day each week, unless the weather is too wet cold or windy, and continue to the end of September. This method produces a very good guide to how population numbers change as they emerge and then reach their maximum numbers. Looking at the maximum reached gives an indication of how each species is faring overall, and looking at how numbers change both before and after this maximum shows how they are affected by the change in weather from year to year and ultimately how the larger scale changes in climate are affecting them.

Common Blue Damselfly

Common Blue Damselfly

Large Red Damselfly

Large Red Damselfly

It is good to see from all this data that, while numbers may go up and down from year to year, all the species being assessed are holding their own. But we have even seen one species, Azure Damselfly, significantly increase its population over the past 7 years, a reflection of a broader change in UK distribution in response to a warming climate, and the warmer summers also appear to be helping to increase the population of Emerald, another of the Damselflies.

Emerald Damselflies

Emerald Damselflies

An additional activity over the past 2 years has been to assess which flowers are most visited by the different bumblebee species, and their abundance. This has helped to explain some of the differences in bumblebee distribution around the reserve and has also highlighted which flower species are particularly important, and these are not the same for all of the bumblebee species. It is hoped that this information will help to guide suppliers of wildflower seed mixes and planners of habitat restoration on how better to help this important group of insect pollinators which have shown such declines in recent years around the country.

Common Carder Bumblebee on White Dead-nettle

Common Carder Bumblebee on White Dead-nettle

Garden Bumblebee approaching Bush Vetch

Garden Bumblebee approaching Bush Vetch

Butterflies can also be abundant, especially the Ringlet.  They may look drab at first glance, but closer inspection reveals the exquisite detail of their patterning.

Butterflies can also be abundant, especially the Ringlet. They may look drab at first glance, but closer inspection reveals the exquisite detail of their patterning.

So, if you are out and about from April to September you may see groups of folk with clipboards, binoculars and sometimes insect nets walking slowly along one of their transects recording what they see. Stop and talk to them and I am sure they will be pleased to help you understand what it is all about; explain what some of these insects are doing; and show you how to see and appreciate some of the beautiful insects that share Loch Leven NNR with the birds.

Surveying the Old Railway ponds

Surveying the Old Railway ponds

About Craig.Nisbet

Reserve Officer Loch Leven National Nature Reserve Scottish Natural Heritage
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