Gobions Butterfly Report 2000
by Linda Jonas
This was the most disappointing year since we started the survey in 1990. The weather was poor with the wettest spring since 1983, followed by a hot May and then four weeks of cool cloudy weather through the last two weeks in June/first two weeks in July which is our main recording period. So Skippers, Gatekeepers & Meadow Browns were very badly hit. Small Tortoiseshells also had an appalling year and in fact only Peacocks seemed to retain their numbers. However even the clouds of 2000 had a silver lining as we recorded the Ringlet for the first time in Leach Fields, a species I felt sure we had and am very pleased to have been proved right.
Our original survey was sending its results to Butterfly Conservation's Millennium Atlas project up until 2000, and headline results of this major country-wide survey have just been released. Unfortunately it is not a healthy picture with virtually all species in decline, although some species faring worse than others. At the bottom is the High Brown Fritillary which has declined by 77% since the 1970's and Wood White, Pearl-bordered Fritillary, Marsh Fritillary, Large Heath, Silver-studded Blue, Duke of Burgundy and Dingy Skipper are all in a serious condition. Over the past 200 years 34 of our 59 species have undergone substantial decline, five have become extinct and 15 have been lost from over 50% of their range. Some species considered as common, three of which were regularly recorded when our survey began - Common Blue, Small Copper and Small Heath - are showing local serious decline. There is a little good news in that some 15 species have spread further north over the country as a whole including Holly Blue, Comma, Purple Hairstreak, Speckled Wood and Ringlet.
The main cause of butterfly decline is habitat destruction through intensification of agriculture, planting of conifer forests, & changing of habitat management (eg decline of coppicing & livestock farming) which fragments and isolates butterfly habitat leading to colony extinction and lower chances of re-colonisation. Climate change has added to these problems for habitat specialist butterflies (like the Wood White) but has enabled species expansion among what are known as Wider Countryside species - eg Speckled Wood, Holly Blue - have been able to take advantage of the periods of warm weather during the last decade particularly as their main habitat - hedges, roadside verges, nettle patches - are still relatively common.
Butterflies respond quickly to subtle changes in habitat and climate and are therefore good indicators of the quality of our countryside. It is very important that we try and rebuild the wildlife-rich landscape of the past not just for sentimental reasons but for the real health of our environment and there are quite simple, cheap things which members of the public, local authorities, landowners as well as farmers can do: things like leaving roadside verges, areas of parks such as Gobions Open Space, uncut until the autumn, leaving nettle patches in corners of gardens and small areas of long grass and planting wild flower species such as scabious, birdsfoot trefoil, & ladies smock. Such planting in suburban gardens is particularly helpful as it helps to create a corridor of nectar plants which help to overcome the isolation of butterfly colonies.
Butterfly Conservation have asked us to take part in a research programme they are carrying out together with MAFF into the effects of pesticides & herbicides on butterfly species. We have been chosen not only because Leach Fields are one of the few remaining sites of unimproved grassland in Hertfordshire but also because our 10-years of records represent one of the best surveyed transects in the country. Our past records are being put onto a software programme at present and will become an example for other amateur groups of how to record a transect. The analysed data will be sent to us in due course and our subsequent records will be added during the research programme. So far this year, regrettably, April has been the worst month ever with not one field survey being possible due to inclement weather so I am hoping predictions of a hot May and June will turn out to be true.
Linda Jonas, spring 2001
All sections of the 2000 report
Gobions Report 2000 Introduction
Butterfly Report 2000
English Heritage Register - Gobions