Building a butterfly baseline

We have been monitoring butterflies in the woods since 2015 to find out more about what’s there, and see what effect the conservation work is having. Butterflies vary a lot from year to year; change can only be detected by recording consistently over a number of years.  So we have established a standard recording route, running from the Sawmill to Wooston Castle, down the valley to the east of the Castle, back along the river past the weir, then up the valley just east of the weir back to the contouring track and back to the Sawmill – a little over 2 miles.  Using the Butterfly Conservation Trust’s standard recording methods, we walk this route once a week from April to September, as long as the week includes a day with reasonably butterfly-friendly weather (over 15C, reasonably sunny, and not too windy).So far, we have recorded  thirteen species.  Speckled Wood are fairly common in spring, summer and early autumn;  Brimstone, Orange Tip and Green-veined White are frequent in spring and early summer; Meadow Brown, Ringlet, Gatekeeper and Silver-washed Fritillary are common in later summer.  Peacock, Red Admiral, Large White and Small Tortoiseshell have been seen occasionally, and we have seen one Dingy Skipper.  Not a large number of species, no particularly scarce species, and numbers are not large – the largest number seen on one day on the recording route is just over 50, and the average daily total is only about 10 – about one butterfly for each 400 yards walked!

There are a number of likely reasons for this – including dominant conifers; mainly north-facing slopes, which warm up slowly in summer;  shortage of nectar-producing plants because of the shortage of open ground and the dominance of bracken; and recent disturbance especially of track verges.Particular species have varied from year to year – Brimstone and Meadow Brown were up in 2015; Green-veined White, Silver-Washed Fritillary and Speckled Wood were up in 2016; Ringlet and Speckled Wood were up in 2017;  but as yet there is no evidence of significant long-term change.Hopefully, numbers and diversity will increase as conifers give way to broad-leaved native trees, and as ground flora and open ground increase, especially if we can successfully reduce the dominance of bracken.  It would be nice to see other scarcer fritillary species, especially High Brown and the Pearl-bordered Fritillaries; however our predominantly north-facing aspect doesn’t help.If anyone is interested in learning to record butterflies and helping with the recording, we’d love to hear from you.By Bas PayneWith thanks to the Butterfly Team: Bas Payne, Wendy Fisher, Joyce Halliday and Gavin Wakely.