BUTTERFLY SURVEY of COCKLAWBURN BERWICK UPON TWEED. April to September 2012

Transcription

1 A Report on the 2012 Survey BUTTERFLY SURVEY of COCKLAWBURN BERWICK UPON TWEED April to September 2012 Female Common Blue butterfly by Iain Cowe. by Berwick Wildlife Group Berwick Wildlife Group Page No 1 16/03/2013

2 Index Page 1) Acknowledgements 3 2) Introduction 4 3) Method 4 4) Observations 5 5) Evaluation. 10 6) References 12 7) Appendix 1 Details of survey area as supplied to BC 13 8) Appendix 2 Methodology 15 9) Appendix 3 Weather 16 10) Appendix 4 Links to details of butterfly species 18 Berwick Wildlife Group Page No 2 16/03/2013

3 Acknowledgements The work grew out of the interest of Elizabeth Bamford who contacted Butterfly Conservation and organised the volunteers, then together with Fiona Aungier and Malcolm Hutcheson discussed the project with Natural England, laid out the transect and undertook an initial habitat survey. The following members of the Group took part in the field work: P. Campion, A. Morton, T. Collin, M. Hardie, R. Hardie, S. & J. Rae, P. Simpson, M. Strachan, M. Williams. Fiona Aungier carried out the habitat survey, drew the maps and collated the weekly data. John Rae transferred the results to the database, tabulated and analysed them. Fiona and John wrote this report. Malcolm Hutcheson provided the information on weather in the Appendix. Finally we would like to thank Greenwich Hospitals' Manager, John Whiteford, Borewell Farm, Scremerston, who gave permission for the survey to go ahead on his land. Picture 1 Searching for butterflies in the dunes at Cocklawburn Berwick Wildlife Group Page No 3 16/03/2013

4 Introduction Cocklawburn is situated on the coast 5km south of the river Tweed at approx. NU Between the beginning of April and the end of September 2012 volunteers from Berwick Wildlife Group undertook their fourth butterfly survey of Cocklawburn, near Berwick. (See Berwick Wildlife Group s website for a report on the 2008 to 2011 surveys) As in previous years, the purpose of this survey was to gather observations of butterfly species for Butterfly Conservation and partner organisations as part of the United Kingdom Butterfly Monitoring Scheme (UKBMS), a long-running citizen science programme begun in 1976 and now operating on over 1,000 sites each year (Fox et al, 2011). The weekly counts at each site are combined to give an annual total of each species, which reflects the relative abundance of butterflies present. The data also contribute to the Butterflies for the New Millennium (BNM) recording scheme which maps the distribution of butterfly species across the UK. Together these schemes make British Butterflies one of the best-studied wildlife groups on the planet. The data from Cocklawburn is also used as part of the monitoring of a grazing regime, instituted to maintain the diversity of flowering plants in this area under an Environmental Stewardship agreement between Natural England and the occupier. The surveys, in all years, took place between the 1 st of April and the 29 th of September. A total of 691 butterflies of 11 species were observed over the 26 week period in 2012, better than 2011 but still lower than previous years. Method. Year Total Number of Number of species butterflies observed The survey followed the standard practice for butterfly transects, as described on the UKBMS website ( ) see Appendix 3. A fixed route (transect) is walked every week from the beginning of April to the end of September, under weather conditions that are suitable for butterfly activity. The recorders identify and count individual butterflies seen along the transect. The butterflies recorded are therefore only a small sample of those present in the area throughout the summer, but the method allows valid comparison of the abundance of each species between weeks or years and between sites throughout the UK. The data are submitted to UKBMS. Berwick Wildlife Group Page No 4 16/03/2013

5 A Report on the 2012 Survey OBSERVATIONS Table 1. Summary of Observations by Date Date Week Skipper Large White White Greenveined White Orange Tip Copper Common Blue Red Admiral Painted Lady Tortoise shell Peacock Comma 01/04/ /04/ /04/ /04/ /05/ /05/ /05/ /05/ /06/ /06/ /06/ /06/ /06/ /07/ /07/ /07/ /07/ /08/ /08/ /08/ /08/ /08/ /09/ /09/ /09/ /09/ Grand Total Dark Green Fritillary Wall Meadow Brown Ringlet Heath Total Adult Berwick Wildlife Group Page No 5 16/03/2013

6 Table 2. Summary of Observations by Transect Transect Skipper Large White White Greenveined White Orange Tip Copper Common Blue Red Admiral Painted Lady Tortoise shell Peacock Comma Grand Total Dark Green Fritillary Wall Meadow Brown Ringlet Heath Total Adult Berwick Wildlife Group Page No 6 16/03/2013

7 A Report on the 2012 Survey Diagram 1. Total Butterfly Count Graphed by Weeks 160 Cocklawburn Dunes Heath Ringlet Meadow Brown Number of Wall Dark Green Fritillary Comma Peacock Tortoise shell Painted Lady 40 Red Admiral Common Blue 20 Copper Orange Tip Green-veined White 0 White Week Numbers Large White Skipper Berwick Wildlife Group Page No 7 16/03/2013

8 A Report on the 2012 Survey Diagram 2. Total Butterfly Count Graphed by Section. N umber of Cocklawburn Dunes Transect Heath Ringlet Meadow Brown Wall Dark Green Fritillary Comma Peacock Tortoise shell Painted Lady Red Admiral Common Blue Copper Orange Tip Green-veined White White Large White Skipper Berwick Wildlife Group Page No 8 16/03/2013

9 Diagram 3. Weather data from the transects Temperature Degrees C Week Number Windspeed Beaufort Scale Week numbers Force 1 = 1-3 mph Force 2 = 4-7 mph Force 3 = 8-12 mph Force 4 = 8-12 mph % Sun 120% 100% % Sun 80% 60% 40% 20% 0% Week Numbers Berwick Wildlife Group Page No 9 16/03/2013

10 Evaluation. The UKBMS [United Kingdom Butterfly Monitoring Scheme] mission is to assess the status and trends of UK butterfly populations for conservation, research and quality of life (UKBMS Annual Report 2011). To help achieve this, in 36 years more than 5,000 volunteers have walked over half a million km. and counted over 17 million butterflies. Our Cocklawburn work is a tiny contribution. There is no doubt that the dismal summer weather of 2012 was extremely bad for butterflies throughout the UK. Cold and wet weather is a dangerous double whammy for butterflies it increases the mortality of caterpillars and also limits the ability of adult butterflies to find mates and lay eggs, which leads to reduced numbers in current and future generations ( ). Butterfly Conservation go on to say that numbers of white butterflies and the Vanessids (Red Admiral, Tortoiseshell, Peacock, Panted Lady) were down nationally in 2012, and the Common Blue was particularly badly hit. Table 3. Total numbers of each species recorded on the transect in successive years Species Skipper Large White White Green-veined White Orange Tip Copper Common Blue Red Admiral Painted Lady Tortoiseshell Peacock Dark Green Fritillary Wall Grayling Meadow Brown Ringlet Heath TOTAL Table 4. Total numbers of butterflies on the transects at Cocklawburn and Tommy the Miller s Field. Total numbers of butterflies counted Cocklawburn Tommy the Miller s Berwick Wildlife Group Page No 10 16/03/2013

11 The results from Cocklawburn in 2012 seem not to reflect the details of this national picture. More butterflies were counted on the transect at Cocklawburn in 2012 than at our nearby but inland site at Tommy the Miller s Field in Berwick, and more at Cocklawburn in 2012 than in Numbers of Common Blues, a species which had a very bad year nationally, were higher at Cocklawburn than in 2011, in fact the second highest totals in the 5 years of our records there. Meadow Browns followed national trends and had a (reasonably) good year, but whites and Ringlets fared badly, and no Wall Browns at all were recorded from the transect. The success of the Common Blue might have been because in this very wet year the plants at Cocklawburn, including the Common Blue s food plant Birdsfoot Trefoil, grew unusually well. Also on this very well drained (sandy) and windy (seashore) site, rain-damp vegetation may have dried quickly allowing caterpillars and butterflies to get on with their lives. This certainly lends weight the theory that in an inclement season, say unusually wet, butterflies at drier sites will benefit, so that the species thrives somewhere and can re-populate other places when conditions return to normal. Suitable habitats providing a variety of conditions are therefore required to maintain a population. Land use change also affects butterfly numbers. At Cocklawburn since 2008 the dunes have been grazed in winter by cattle, specifically to increase the number of herbaceous plants as opposed to grasses. Butterfly recorders have commented on increased numbers of flowers on much of the site, but it is hard to distinguish the results of grazing from weather-related effects. Over all, butterfly numbers are falling in much of the UK. Butterflies are the most threatened wildlife group; more than three-quarters of Britain s 57 resident species are declining and over 40% are listed as Priorities for Conservation. More than 80 moth species are also at risk. (Butterfly Conservation, 2012, ). Climate change may bring warming over-all, but with wetter winters, more unreliable summer weather and increasingly violent weather events, butterflies will struggle. Perhaps more serious is land use change. At Cocklawburn the site is managed with dune vegetation (and dependent butterflies) in mind, and the good drainage may enable insects to cope with the wetter summers expected in future. The benefits of this site for butterflies could be increased if it became part of a larger network of butterfly-friendly sites (helping plants and other animals too of course). Butterfly Conservation now advocate landscape-scale conservation. Their report Landscape-scale conservation for butterflies and moths: lessons from the UK, (Butterfly Conservation, 2013, ) lends weight to the recent Government paper by ecologist Professor Sir John Lawton Making Space for Nature (Lawton et al, 2010) which states that we must make habitats far bigger, better managed and more connected if species are to survive in the future. We hope our data from Cocklawburn will help to point the way to more successful conservation in future throughout the UK. Berwick Wildlife Group Page No 11 16/03/2013

12 References Berwick Wildlife Group, Survey Reports. Botham, M.S., Brereton, T.M., Middlebrook, I., Randle, Z. and Roy, D.B United Kingdom Butterfly Monitoring Scheme Report for Centre for Ecology and Hydrology. Should be on UKBMS website soon. Butterfly Conservation Website: Butterfly Conservation, Washout summer hampers butterflies. Butterfly Conservation, Butterfly Survival Blueprint unveiled. Ellis, S., Bourn, N. A. D. and Bulman, C. R. (2012) Landscape-scale conservation for butterflies and moths: lessons from the UK Butterfly Conservation, Wareham, Dorset. Available from Fox, R., Brereton, T.M., Asher, J., Botham, M.S., Middlebrook, I., Roy, D.B. and Warren, M.S The State of the the UK s Butterflies Lawton J H, Brotherton P N M, Brown V K, Elphick C, Fitter A H, ForshawJ, Haddow R W, Hilborne S, Leafe R N, Mace G M, Southgate M P, Sutherland W J, Tew T E, Varley J, Wynne G R (2010) Making Space for Nature: a review of England s wildlife sites and ecological network. Report to Defra. United Kingdom Butterfly Monitoring Scheme (UKBMS), Methods for recording butterfly transects. Berwick Wildlife Group Page No 12 16/03/2013

13 A Report on the 2012 Butterfly Survey Appendix 1 Details of Survey Area as supplied to Butterfly Conservation Site Name OS Grid ref. (6 fig.) Transect length (m) Cocklawburn Dunes (inland from Mid County Northumberland & Far Skerrs). OS map no. NU Year transect 2008 (1:50 000) established Other Transect width (m) 5 6 1,500m 0 Tick one Overall habitat Coastal dune grassland. description Land Use If the transect is on a disused industrial Rail site tick the type way Hab. Code(s) Qua rry Pit/m ine B1.4 Other - add to notes Sites conservation Type of SSSI, ESA V status recorder Recorder Berwick Wildlife Group, 23 Castle Terrace, Berwick upon Tweed, details TD15 1NR Owner details Greenwich Hospitals. Manager John Whiteford, Borewell Farm, Scremerston, TD15 1RJ TARGET NOTES Land Use: Although at first glance normal dune grassland (newest near sea) and rough pasture, site includes lime kiln spoil heaps, an old brick pit, clay areas, tracks, etc. Area subject of Management Agreement, including light grazing by Aberdeen Angus, monitored by Natural England and Berwick Wildlife Group. Berwick Wildlife Group Page No 13 16/03/2013

14 Summary of Habitat Section Number Grid Ref. (for mapping) 1 NU NU NU NU NU Section Length (m) HABITAT MANAGEMENT Description/notes & main species Code Description/notes C o d e B1.4 Unmanaged 350 Dune grassland, including quite "young" dune, with Anthyllis, Geranium sanguineum, Astragalus. Ungrazed by stock. Some trampling. 250 More mature dune grassland and rough pasture thistles, hawkweeds, dock, etc. 250 Limestone spoil heaps, tracks, etc. Lotus, Thymus, Geranium sanguineum. 300 Rougher grassland, more thistles, some bushes, willowherb, improved pasture nearby. 300 Mature dune grassland, rough pasture and marsh and limestone spoil. Very variable substrate and hence flora. E2.1/ 2.2 E2.1/ F3.1 E2.1/ E3 + E1.2 Light cattle grazing Part ungrazed, part light cattle grazing Light cattle grazing Light cattle grazing M 1 M 1 M 1 M 1 Berwick Wildlife Group Page No 14 16/03/2013

15 Appendix 2 Method Butterfly transects are a way of measuring changes in the abundance and variety of butterflies present at a site from year to year. Full (all species) transects are labour intensive and require a commitment to record weekly throughout the main six-month period in which butterflies fly in the UK. The method adopted for this survey follows that laid down by Butterfly Conservation. Establishing the transect. The transect was identified by Elizabeth, Fiona and Malcolm and consisted of a route 1450m in length that gave a fair representation of the habitats and other features present in the field. This transect was fixed so the same route could be followed each week and also each year so comparisons can be made. It was subdivided into 5 sections, approximately equal in length, with each section representing a change in habitat or management type. When to Record. Recording took place once a week from April 1st to the end of September. Transect counts were ideally made between 10:45 and 15:45 hours. Transect walks were only carried out in warm (13 C or more), bright, fairly calm weather. Windspeed 4 or below on Beaufort scale in exposed place. The minimum criteria were 17 C if overcast or 13 C if at least 60% sunshine. How to Record. To aid species identification each group had a Guide to the Butterflies of Britain produced by the Field Studies Council. The transect was walked at a slow, steady pace counting all butterflies seen within a fixed distance of 2.5m either side of the transect line and 5m ahead. The same route along the transect was followed each time. Before starting, record was taken of Week No, Date and Recorders and, both before and after walking the transect, the Time, Temperature and Windspeed. % Sun was recorded at the end of each section of the transect. The Transect was walked recording numbers of the various species of butterfly seen on that section of the transect. After the transect had been walked the observations were given to Fiona who entered them into a standard Excel document, one for each weeks' survey, and John transferred this to the main UKBMS database via their program TransectWalker. Berwick Wildlife Group Page No 15 16/03/2013

16 Appendix 3 Monthly Weather Reports April. After the mild, dry start to the year, April has been a bit of a disappointment. Temperatures were low throughout the month with the wind settling in a north-easterly quarter. The Meteorological Office is blaming a change in the jet stream for dragging down cold air from the north. The effect has been to hold up spring migration, as birds do not migrate against a northerly wind. It has also been detrimental to insects on the wing during April. Rainfall returned with a vengeance after the dry winter, several days with 24 hours of rain. The wettest of these was the 10th, with a total of 21mm (0.8ins) and light winds. Between the wet days there were many days with heavy showers, some of them with sleet and hail with a cold wind, and in between bright sunshine typical April showers. Total rainfall for the month was 97.5mm (3.8ins), well above the average April rainfall of 41mm (1.6ins) over the last decade. May. Winds from an easterly direction brought a cold beginning and end to the month. Cold nights came with the cool winds during the first week, resulting in a minimum temperature of 2 C (35 F) on the 6th and 8th, with a touch of frost. Signs of summer came in the third week with a few warm days from the 22nd to 28th, the temperature reaching 21 C (70 F) on the 27th. Breeze off the sea brought morning sea mists from the 23rd to the 25th but the sunny conditions resulted in reasonable mid-day temperatures. Two wet spells brought 24 hours of rain on the 10th/11th (34mm, 1.3ins) and the 31st (22mm, 0.9ins). Heavy showers on the 14th came with hail and a rumble of thunder. The total rainfall was 86mm (3.4ins), a little above average for May. June. Our hopes of a flaming June certainly did not materialise this year. The first fortnight came with sunshine and occasional showers, then heavy rain made it the wettest June here for the past 12 years (and no doubt beyond if we had the data). There have been notable periods of torrential downpours, with deluges coming overnight on the 10th, 17th and 27th. On the afternoon of the 28th a period of recurring thunder storms, known as a super cell, swept northwards along the coast, bringing 25mm (1in) of rain in a four hour period. Road and rail disruption followed. Total rainfall for the month was 128.5mm (5.1ins), the local June average being 80mm (3.1ins). For much of the month temperatures were restricted by a persistent cool wind coming from a north or easterly direction. There were particularly cold nights mid-month, with the thermometer falling to 6.5 C (43.7 F) on the 14th and 18th, although the temperature reached 21 C (70 F) in the sunshine on the final day of the month. The cool, wet conditions have brought problems to breeding birds, particularly ground nesting species, and also to insects such as moths and butterflies. July. The wet conditions of June ran into the first two weeks of July, with rain occurring on most days until mid-month. Some downpours were recorded with 35mm (1.4ins) on the 7th, 20mm (0.8ins) on the 11th and 26mm (1.0in) on the 18th. The total for the month was 140mm (5.5ins), by far the wettest July for a decade and beyond. Temperatures were nearing the seasonal normal on some days with a mixture of variable light winds and sea breezes, but not July heat wave temperatures. The highest daytime temperature was 23 C (73 F) recorded on the 23rd. During the last week there were cooler daytime temperatures and several cold nights, with 9 C (48 F) recorded on the 20th and 6 C (43 F) on the 30th, bringing with it a heavy dew and the thought of Autumn coming early. August. The month passed by with a mixture of weather conditions, with average temperatures, variable winds, but a lack of any settled spell of the expected warm, Berwick Wildlife Group Page No 16 16/03/2013

17 sunny days. The first two weeks brought quiet days with some sunny spells and light sea breezes. This changed on the 16th with a day of dull, damp sea mist and reduced visibility. The following night the temperature fell to a low of 9 C (48 F). The latter half of the month brought a wet spell over three days (16th 18th) with 29mm (1.1ins) of rain and consequent difficulties with the start of the harvest, followed by sunshine and heavy showers. Yet another twist came on the last night (30th) when the temperature dropped to 2 C (36 F) with an air frost, and a slight ground frost in places. Nobody can call the British weather boring! Total rainfall for the month was 67mm (2.6ins) which, considering this has been the wettest summer in the past 100 years, is surprising. Our average rainfall figure for August over the last ten years is 81mm (3.2ins). Berwick has perhaps been doing better than elsewhere this month. September. The first 10 days of the month were dry with warm conditions and temperatures reaching a balmy 23 C, 74 F on the 8th. It was all change on the 11th with a cold north-west wind and rain all day (17mm, 0.67ins). The rest of the month was cool, with several days of persistent rain, i.e. 21st (20mm, 0.8ins) and 25th (26mm, 1.0ins), the latter accompanied by unusually early severe gales, bringing the deaths of many immature seabirds and migrants, and presumably insects as well. Overnight temperatures remained cold, but keeping above freezing point, with no frosts recorded. Total rainfall for the month was 91mm, 3.6ins, a figure well above the average of 57mm (2.3ins) for September during the last decade. Berwick Wildlife Group Page No 17 16/03/2013

18 Appendix 4 Observed species details and status in the United Kingdom Butterfly Monitoring Scheme database. Skipper - Large White - White - Orange Tip - Green-veined White - Copper - Common Blue - Red Admiral - Tortoiseshell - Peacock - Dark Green Fritillary - Wall Brown - Grayling - Meadow Brown - Heath - Ringlet - Berwick Wildlife Group Page No 18 16/03/2013