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| 40 years of saving butterflies, moths and our environment |
| Butterfly Conservation | |
| 40 years of saving butterflies, moths and our environment |
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RECORDING - Archive Material Devil's Dyke 2006Authored by Sharon Hearle (Nov 2006)
It was a very difficult May for surveying butterfly with many wet and windy days. Dingy Skipper was first seen on 10th May (3rd May in 2005 and 6th May in 2004). The highest count was 18 on 25th May which is broadly similar to previous years. It is possible that higher counts might have been achieved on days with warmer weather but the transect walker was elsewhere in the region looking for Grizzled Skipper. The Dingy Skipper seems to favour the first 200 metre section NW from the car park area and will certainly benefit from management work to mow and clear grassland this winter. One rather tatty Dingy was even seen in the car park area in early June. The actual Green Hairstreak figures for the transect are quite low even though the butterflies were seen all along the Devils Dyke. A brief visit looking specifically for the butterfly all over the south facing bank revealed much higher numbers especially along the hawthorn bushes lower down the slope.
The Small Heath appeared in good number in 2006 with a particularly impressive third brood continuing right to the end of September. The adjacent Newmarket Heath especially next to the lower parallel bank where there is an artificial sandy track is also very good for Small Heath. Sadly no Wall butterflies were recorded although these are generally more frequent toward the Reach end of the Devil’s Dyke. Other highlights included singletons of White-letter Hairstreak and a couple of Clouded Yellows. The entire length of the Devil’s Dyke has benefited from a Heritage Lottery Fund grant for the last 5 years which is shortly coming to an end. The Project Officer has already moved on to a new post and the challenge for the future will be to maintain the remaining chalk grassland and newly cleared areas with new sources of funding. Landowners will be encouraged to enter their section into Higher Level Countryside Stewardship. If anyone would like to help with this transect walk, particularly to provide holiday cover and avoid missed weeks I would be very pleased to hear from you (contact details shown below).
Fleam Dyke 2006Authored by Roger Lemon
On the morning of 10 May, six of us, including Val Perrin and Sharon Hearle, met for a walk along the Dyke to discuss what might be achieved. During the walk, nine butterfly species were recorded, including good numbers of Green Hairstreak, well distributed between the Fulbourn end and the A11. Clearly, it was too late at that stage to do a complete season of transect counts and, in order to include all interesting sections of the dyke, where both Green Hairstreaks and Chalkhill Blues had been recorded, the transect would be much longer than the 1-2 km recommended. In fact, to include the lower path in the shelter of the bank as well as the top of the bank between the A11 and Bedford Gap, a total transect of about 3.4 km was required. It was decided to use the remainder of the 2006 season as a trial run and conduct fortnightly counts, results and experiences to be reviewed before making plans for 2007. A rota involving four recorders, namely myself, Vince Lea, Trish Agnew and Julia Napier was arranged. Nine transect counts were conducted between early June and September but unfortunately, plans were disrupted by bad weather in May and August. One count, scheduled for mid-May was abandoned and a count planned for 23 August was delayed until early September. A total of 22 species was recorded. Three species, seen in 2004, were not recorded in the transect counts this year. These were the Small Copper, Peacock and Clouded Yellow, although I did see one Peacock when returning along the dyke after the count on 26 July.
The most abundant species in the transect counts was the Meadow Brown (464), followed by the Small White (395) and Gatekeeper (330). Essex and Small Skippers were recorded in good numbers (89), in a ratio of about 5 to 1. The most common vanessid was the Painted Lady (73) followed by the Red Admiral (32), which were seen mainly in September. Small Tortoiseshell and Comma numbers were low (7 and 9 respectively). Other species were Brimstone (61), Large White (48), Green-veined White (27), Orange-tip (2 - but we missed the main flight period), Brown Argus (27), Common Blue (64), Holly Blue (2), Speckled Wood (19), Small Heath (16) and Ringlet (34). A single Green Hairstreak was recorded on 2 June. In the near future, further decisions on the management of the dyke will be required. It is hoped that these will include plans to encourage the population of Chalkhill Blues and to ensure that a population of Green Hairstreaks, which occur mainly in the scrub areas, is maintained. A more complete set of transect counts will be planned for 2007. Any volunteers who would like to be involved please contact Roger Lemon on 01799 584563 or Ten Years of Butterfly Monitoring at Writtle CollegeAuthored by Robin Field, Tim Gardiner and Graham WatkinsTwo butterfly transects were set up in 1996 on the Writtle College estate near Chelmsford, Essex. The reason these transects were started was that over the previous ten years the estate had changed from a very intensive mixed farm to one which had started to put in conservation measures to improve the environment. These included replacing hedges that had been removed, planting field corners with trees and creating small areas of wildflower grassland. It was felt that some monitoring work was required to assess how effective these measures were. A study by staff and students regarding the state of the college estate in 1976 (Neate, 1976) contained a chapter on butterflies, but unfortunately in 1976 the transect method was still in its infancy and only observations were noted. They did find that there were 20 species of butterflies present on the college estate, so, butterfly species richness in 1976 could be compared to what was observed 20 – 30 years later. In 1996, two transects, with a total length of 5.993km, were established across the college estate. These covered all the major habitats with one transect having nine sections and the other eight sections. They were set up as laid out under the Butterfly Monitoring Scheme (BMS) criteria. These transects were walked once a week, with all butterflies observed recorded, from April to the end of September each year provided the weather conditions were suitable. The two transects became part of the BMS in 2001 and continued to be monitored by the authors. Results The total number of butterflies observed on the transects has varied from a high of 2,878 in 1997 to a low of 1,215 in 2002. The species richness has fluctuated between 24 in 1996 and 18 in 2005 (see the Table at the end of the report). Seventeen species have been recorded every year but three species have disappeared in the last few years. Wall and Ringlet have not been since 1997 whilst Brown Argus has not been seen since 2000. Two species, painted Lady and Clouded Yellow, were recorded in years when high numbers reache Britain and Small Copper were not recorded on the transects every year but are known to be in low numbers in certain areas across the estate. Butterfly species diversity has reduced by three species over the ten year period when account has been taken of the migrant species. The first species lost was Wall, and this follows a national decline at inland sites. The loss of Ringlet was due to only a small area of suitable habitat being available. The available habitat was increased but the numbers were already too low to sustain the population. Brown Argus has been increasing and decreasing its range in Essex over the last fifteen years and was seen for three years on the transect before disappearing again. Out of the 24 species observed over the ten years, ten are in decline, three increasing, eight remain stable and three were lost. Several species have sustained reductions in abundance over the ten-year period. Large Skipper has significantly reduced since 1999, having the largest fluctuations reducing from a high of 199 to a low of one. The reasons for these changes are not known as there was plenty of long grassy habitat which remains uncut and there were nectar sources nearby but the reduction follows the national trend. Orange Tip has also reduced in numbers but this may be due to a run of poor spring weather over the last few years. The reason for the decline of Peacock was unknown. Two species, Small Tortoiseshell and Small Heath have had severe fluctuations during the last ten year period. Small Tortoiseshell had declined across the country but the decline was identified one year earlier in agricultural habitats than on BMS transects. It has since recovered to pre-decline numbers. Small Heath abundance was very low in the period 1999 – 2001 but since has made a slight recovery. The decline may have come about because Small Heath favours short turf and those years had high summer rainfall which encourages grass growth. Three species have increased in numbers over the ten years. The first species, Speckled Wood, which was not recorded on the site in 1976, has been increasing across the country and, in this study the species rose fron only small numbers at the start of the period to become the third most numerous butterfly by 2005. The second species to increase in number was Meadow Brown. This was not surprising as many wildflower meadows and pastures had been created on the college estate over the last 15 years, thus far more suitable habitat was available. Comma, the third species to increase was following an increasing national trend; this may be due to a more wildlife friendly management of hedgerows in agri-environmental schemes such as the Countryside Stewardship Scheme (CSS). Whilst 71% of all British butterflies are reducing nationally, this includes a wide range of our most threatened butterflies. This study at Writtle, confined to only common butterflies, suggests that 42% are declining, 33% steady, 12.5% increasing and 12.5% lost from the college estate in the last ten years. What must be remembered when looking at these figures is that everything possible has been done to manage the estate in a wildlife friendly manner for the last 15 years and the farm has been in CSS since October 1996. Conclusions: The analysis of long-term data has shown worrying trends for common butterflies. Nearly 55% of species seen on the Writtle College transects are either in decline or have already been lost over the ten years. This was all happening on a site managed positively for wildlife and especially butterflies. If such a large loss can occur on favourably managed farmland what can the effects be in the wider countryside? The grasslands habitats established at Writtle were not small scale, they were field size and were either inter-connected or connected by hedgerows, ditches, streams, permanent set-aside and wide grassy margins. One problem with some areas of the grass margins and pastures may be that they were sown with commonly used cultivars of agricultural grasses and wildflowers. Recent research (see Grass Margin Research) suggests that the use of native grasses and wildflowers, even though more expensive, can produce habitats which support four times the number of butterflies and significantly greater species richness. Acknowledgements: - The authors would like to thank other recorders including Michelle Pye, Zoe Ringwood & Emma Sellars who have walked the transects on various occasions. The total numbers of butterflies recorded since 1996 (COLLEGE and LORDSHIP transects added together) are shown in the following table.
The following charts indicate the trends in numbers for the most common species:
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