Butterfly monitoring is being carried out by Andrew Steele and volunteers from Herts and Middlesex branch of Butterfly Conservation.

As Heartwood is developed, the changing habitat from highly managed arable crops to open grassland and trees will have a big impact on the populations of butterflies.

To establish a baseline, two initial visits by volunteers from Butterfly Conservation in 2009 concentrated on the existing woodlands and surrounding fields (Woodland Trust, 2009). They found the woods generally too dark for much butterfly activity. The small clearing and associated east-west ride in Well Wood contained a few butterflies. Areas of old coppice in Round Wood and Langley Wood, cut about 10-15 years ago, had re-grown and were dark. The pit area at the south end of Round Wood potentially had some interest. They reported that the site contained a good deal of high quality woodland edge habitat where grassy field margins had been unploughed around the edge of the small woods.

True woodland specialists such as Silver-washed Fritillary and White Admiral were not found although both were observed in good numbers in nearby Symondshyde Great Wood on the day of the second visit. Purple Hairstreak was not recorded, but was present in good numbers on the adjoining Nomansland Common. White-letter Hairstreak was not found despite 2 hours searching suitable Elm. The absence of these species was attributed to the lack of woodland management.

The woodland edge of all four woods was attractive habitat for butterflies and Peacocks, Commas and Large Skippers were all present in very good numbers. There appeared to be a small colony of Marbled White on the NW corner of Pismire Spring – this was the least common butterfly recorded on site. Two of the long grass species, Meadow Brown and Ringlet, were both in good numbers. Small Skipper had only just started to emerge and it is likely that it along with Gatekeeper and Essex Skipper will be there in good numbers. Species such as Common Blue, Small Copper, Small Heath and Brown Argus which prefer shorter grass were not found although they are all well distributed in the district.

Since August 2010 Andrew Steele has carried out surveys on standard transect walks as shown on by the purple dotted line on the map (Wood, 2010 and 2011).

Transects are the main method of measuring how butterfly populations change with time. The technique is simple, involving walking the same set route every week in good weather throughout the summer months (from 1 April to 29 September), and noting down the numbers of each species of butterfly seen within about 5 metres. The Heartwood transect takes 88 minutes and was walked 15 times in 2010 and every week (26 times) in 2011 by Andrew Steele. In both years 22 species were seen. (Wood, 2012).

In 2011 there were increases over 2010 for Marbled White, Essex Skipper, Small Skipper, Red Admiral, Common Blue and Purple Hairstreak but loss of Small Copper and big dips in the number of Peacock and Comma see the Table below.

The results for 2012 will be added as soon as they are available.

Butterfly monitoring results for 2011
Butterfly Total seen Max Date First date Last date
Small Skipper 27 14 2 July 13 June 15 August
Essex Skipper 2 2 2 July    
Large Skipper 90 37 13 June 30 May 11 July
Brimstone 12 6 9 May 12 April 13 June 
Large White 296 64 11 July 12 April 26 September
Small White 73 12 23 April 12 April 19 September
Green-veined White 61 9 9 May 12 April 12 September
Orange Tip 110 31 23 April 12 April 23 May
Purple Hairstreak 2 1 25 July 25 July 31 July
Brown Argus 2 1 23 May 23 May 13 June
Common Blue 22 9 15 August 9 May 22 August
Holly Blue 13 7 12 April 12 April 31 July
Red Admiral 16 6 25 July 11 July 22 August
Painted Lady 2 1 19 September 19 September 26 September
Small Tortoiseshell 26 8 11 July 12 April 1 July
Peacock 28 6 25 July 12 April 12 September
Comma 9 3 2 July 27 June 15 August
Speckled Wood 54 13 31 July 12 April 26 September
Marbled White 22 8 2 July 27 June 25 July
Gatekeeper 104 39 25 July 27 June 15 August
Meadow Brown 314 81 2 July 18 April 22 August
Ringlet 81 40 2 July 20 June 25 July

 

Andrew Steel, July 2012