Extending the Use of Butterfly Recording Data in the UK

Extending the use of butterfly recording data in the UK

Final Report

Contract report (Defra contract WC0729) to Defra, Joint Nature Conservation Committee, Natural England, Scottish Natural Heritage, Countryside Council for Wales, Northern Ireland Environment Agency and Forestry Commission

June 2011

Roy, D.B., Middlebrook, I., Cruickshanks, K., Freeman, S., Botham, M.S., Warren, M. & Brereton, T.

Executive summary 1. Environmental changes such as habitat loss and degradation, climate warming and pollution are serious threats to the conservation of biodiversity. Surveillance and monitoring are important tools for measuring the impact of environmental pressures and quantifying the health and functioning of ecosystems. 2. Butterflies have been identified as an important component of the UK Terrestrial Biodiversity Surveillance Strategy. Butterflies are widely accepted as ecological indicators of ecosystem health and meet a number of the criteria for selecting indicator species. In particular, their high reproductive rates, short life cycles and low trophic level allow butterflies to respond rapidly to environmental change. Butterflies also have great popular appeal (something that eludes most insect groups) and are easy to observe and record. 3. This report reviews three years of work to develop the UK Butterfly Monitoring Scheme (UKBMS). This includes a separately published review of the current structure and main functions of butterfly monitoring in the UK. This review assesses the primary scheme, the UK Butterfly Monitoring Scheme and its relationship to other butterfly monitoring activity. 4. The UKBMS is operated by the Centre for Ecology & Hydrology, Butterfly Conservation and the British Trust for Ornithology and is funded by a multi- agency consortium including the Countryside Council for Wales, Defra, the Joint Nature Conservation Committee, Forestry Commission, Natural England, the Natural Environment Research Council, the Northern Ireland Environment Agency and Scottish Natural Heritage. The UKBMS relies on data supplied by thousands of volunteer recorders. 5. The UKBMS operates two principal methods of monitoring butterflies. Site- based assessments of butterfly communities are undertaken using traditional ‘Pollard Walks’ to sample high quality habitats. A complementary Wider Countryside Butterfly Survey (WCBS) was launched in 2009. The WCBS is a reduced-effort approach, sampling randomly selected 1km squares. 6. Methods for assessing trends in individual butterfly species and producing multi-species indicators have been developed from UKBMS data. Butterfly indicators have been published for England, Scotland and the UK. The feasibility of developing an indicator of butterfly populations in Wales and Northern Ireland has also been assessed. Methods for measuring trends in indicators have been developed using time-series analysis through the TrendSpotter program, allowing short- and long-term trends to be assessed. 7. Two methods for developing an indicator of the Impact of Climate Change using population monitoring data have been tested. Both methods are adapted from approaches used to analyse bird data. 8. The first method identifies species whose distributional extent is predicted to be positively or negatively affected by projected climate change. An indicator was then calculated as the ratio or difference between the mean population trend (on monitored sites) of climate positive and negative species. The ratio showed large year-to-year fluctuations, without a clear trend. 9. A second method to calculate an indicator of the Impact of Climate Change measures changes in community composition in response to climate. For each

butterfly species, a Species Temperature Index (STI) was calculated as the mean, long-term average temperature of grid cells it occupies across Europe. A Community Temperature Index (CTI) was then calculated from UKBMS data as the average STI of species present in the community, weighted by the abundance of each species. The year-to-year temporal trend in CTI was then analysed using data from all monitoring sites. There was a significantly positive trend in CTI over time, with butterfly communities becoming more dominated by butterflies that are characteristic of warmer areas of Europe. 10. Analysis of long-term trend data from the UKBMS showed that for wider countryside species, the majority (15 of 25) showed no overall change, whilst equal numbers of species were either increasing or decreasing. In contrast, twice the number of habitat specialist species showed a decline compared to an increase (12 versus six), whilst 30% (8 of the 26) showed no overall change. 11. Of the 24 species of butterfly that are UK BAP Priority Species, 21 are Habitat Specialists. More than 70% of UKBAP Priority species were shown to be in long-term decline (15 of 21 species assessed), although less than 20% (4 of the 21) have declined over the last decade. 12. The decline in specialist species is linked to a range of factors, including habitat loss, changes in land management (including intensification and abandonment of traditional practices), climate change and habitat fragmentation. Habitat specialists tend to be low mobility species restricted to semi-natural habitats, whose isolated and fragmented habitat niches are most difficult to maintain in modern landscapes. Some species have recovered from long-term declines, in part due to conservation efforts, including the Silver-spotted Skipper, the Chalkhill Blue and regionally the High Brown Fritillary and the Heath Fritillary. Successful re-introductions have included the Large Blue and the Marsh Fritillary in Cumbria. Targeted management through agri-environment schemes is contributing to recovery on agriculturally managed land, although conservation efforts in woodland and on protected land have on the whole been less successful. 13. A proposal for the UKBMS over the next 3 years is to run annual wider countryside sampling to a stratified random design whilst continuing the multi and single species transect sampling on higher quality habitat. Analytical developments are proposed to increase efficiency (through implementing methods to analyse individual count data together with transect data). Developing an integrated online recording system is also a high priority.

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Contents Executive summary ...... ii 1 Introduction ...... 1 1.1 Background ...... 1 1.2 Butterflies as Indicators ...... 3 1.3 Current and potential uses of UKBMS for conservation policy and delivery.. 3 2 Methods ...... 4 2.1 Structure and main functions of the UK Butterfly Monitoring Scheme ...... 4 2.1.1 Site-based monitoring of annual butterfly abundance ...... 4 2.1.2 Butterfly abundance in the wider countryside ...... 4 2.2 Accessing UKBMS data ...... 4 2.3 Analysis of trends ...... 5 2.3.1 Models for site-specific annual survey data – species population index 5 2.3.2 Multi-species indicators ...... 5 2.4 Indicator development ...... 6 2.4.1 Methods for a Climate Change Indicator using population monitoring data ...... 7 3 Results ...... 10 3.1 Maintenance, support and development of the volunteer network ...... 10 3.1.1 Volunteer network development ...... 10 3.1.2 Refining existing data collection and analysis methodologies ...... 12 3.2 Wider Countryside Butterfly Survey (WCBS) ...... 12 3.3 Trends in butterfly populations ...... 12 3.3.1 UK and country level indices and trends ...... 12 3.3.2 Trends in published butterfly indicators ...... 14 3.3.3 Development of butterfly indicators for Wales and Northern Ireland . 14 3.3.4 Climate Change Indicator using population monitoring data ...... 16 3.3.5 European indicators ...... 18 3.3.6 Uses of UKBMS data in conservation & research (summary of data use)...... 19 4 Conclusions ...... 20 4.1 State of UK Butterfly Populations ...... 20 4.2 Future development of the UKBMS ...... 21 4.3 A proposal for butterfly monitoring 2011-2014 ...... 22 5 Acknowledgements ...... 24 6 References ...... 25

Appendix 1 – Long-term and short-term trends in UK butterfly indicators ...... 29

Tables Table 1. Project objectives 2008-2011...... 2 Table 2. Sites contributing to the UKBMS ...... 11 Table 3. Summary of butterfly trends, 1976-2010 (unpublished) – summary of trends table for annual report...... 13 Table 4. Summary of trends in UK BAP Priority Species ...... 21

Figures Figure 1. Map of transect locations – all locations, colour-coded by those recorded in the last 5 years versus those not recorded since 2005...... 10 Figure 2. Number of sites contributing to the UKBMS, 1973-2010 – plot of number of sites with data (transect + non-transect) each year...... 11 Figure 3. Trends in country-level butterfly biodiversity indicators ...... 14 Figure 4. Trends in butterfly populations in Wales for habitat specialists (red), generalist (wider countryside) species (green) and all species combined (blue), 1976- 2008...... 15 Figure 5. Fluctuations in composite indice of groups of climate positive and climate negative butterfly species ...... 17 Figure 6: Temporal trends in Community Temperature Index (CTI) ± standard error...... 18

1 Introduction

1.1 Background Environmental changes such as habitat loss and degradation, climate change and pollution are serious threats to the conservation of biodiversity. Surveillance and monitoring are important tools for measuring the impact of environmental pressures and quantifying the health and functioning of ecosystems (JNCC, 2009). Butterflies have been identified as an important component of the UK Terrestrial Biodiversity Surveillance Strategy (http://jncc.defra.gov.uk/page-4409 ) and are widely accepted as ecological indicators of ecosystem health. Assessment of the state of butterfly populations in the UK has been underpinned by standardised monitoring through the UK Butterfly Monitoring Scheme (UKBMS) and its precursor, the Butterfly Monitoring Scheme (BMS).

The BMS was initiated in 1976 by the Centre for Ecology and Hydrology (CEH, formerly the Institute of Terrestrial Ecology) and by 2004 the scheme had grown to around 130-140 transects each year. However, since the inception of the BMS, ‘Pollard Walks’ have struck a chord amongst British naturalists, by giving recorders an opportunity to engage in an activity that is both fun and generates data of high conservation value. Transects have proved an incredibly popular activity, with a plethora of sites established outwith the BMS, and informally co-ordinated by Butterfly Conservation (BC). The first ‘independent’ transects were set up in the late 1970s, followed by a steady rise in number through the 1980s. However, their popularity increased greatly in the 1990s, with a sustained period of expansion, especially in the ancient woodland and calcareous grassland butterfly hotspots of central-southern England.

Between 1998 and 2005, projects funded by the Department of the Environment, Food and Rural Affairs (Defra) and its predecessor, the Ministry of Agriculture Fisheries and Food (MAFF) provided a further major boost to transect monitoring development and established a partnership between CEH and BC to run the scheme. System developments included standardised recording forms, expanding the network of co-ordinators to all regions, support and training programmes, freely available data entry/transfer/analysis software (Transect Walker) and feedback mechanisms (Brereton et al., 2002). By 2003 over 500 independent transects were being walked by over 1000 recorders, with more than 80 new transects established in that year alone.

Between 2005 and 2008 the UKBMS underwent a major re-development and expansion through funding by a broader multi-agency consortium led by Defra (Roy et al., 2010). The major highlights from the UKBMS between 2005 and 2008 were a single scheme for monitoring the changing abundance of UK butterflies, an expanded dataset for reporting species population trends, the development of butterfly biodiversity indicators and the design of a scheme for monitoring butterflies in the wider countryside.

Transect walking has also been established in other parts of the world, e.g. the USA Midwest, Japan and Western Australia. In Europe, eleven transect monitoring schemes now operate (Belgium, Finland, France, Germany, Ireland, Jersey, Ukraine, the Netherlands, Spain, Sweden, Switzerland, UK) totalling over 2500 transects.

This report details the further development of the UKBMS between 2008 and 2011 (Table 1), funded by a multi-agency consortium led by Defra and comprising the Countryside Council for Wales, Forestry Commission, Joint Nature Conservation Committee, Natural England, Natural Environment Research Council, Northern Ireland Environment Agency and Scottish Natural Heritage.

Table 1. Project objectives 2008-2011.

Objective 1. The maintenance of agreed monitoring and surveillance activities, for three years.

1.1 To undertake a programme of surveillance for butterfly populations at selected sites in the UK. 1.2 To maintain and improve efficiency of data capture and reporting. 1.3 To refine existing data collection and analysis methodologies 1.4 To maintain, motivate and where necessary extend a volunteer base capable of undertaking the programme of surveillance. 1.5 To make data on individual sites available on the NBN-Gateway and via other web-based media. 1.6 To implement agreed development plan, produced in component 3.

Objective 2. Annual reporting, assessment and interpretation of population trends for butterflies, for three years.

2.1 To provide site, UK and where possible country level indices and trends for each species, together with means of comparing between site/country/UK indices and trends. 2.2 To provide updated indices and trends for UK BAP species and other species associated with semi-natural habitats (specialists) from the transect network, at UK and Country level. 2.3 To provide annual updates to existing biodiversity indicators for the UK, England and Scotland. 2.4 To develop and apply a method for assessing statistically significant change in the UK and Country level biodiversity indicators.

Objective 3. The production of a costed development plan for the future of butterfly surveillance and monitoring, within one year.

3.1 To produce a set of costed and critically assessed proposals for the future of butterfly monitoring and surveillance. 3.2 To present these proposals with the scientific, volunteer and funding community and to systematically document their response. 3.3 To implement the proposals, as funding permits.

1.2 Butterflies as Indicators Butterflies, birds and vascular plants, are the most frequently monitored taxonomic groups in the UK and Europe (de Heer et al., 2005; Thomas, 2005), mainly due to their high popularity among amateur naturalists. Several ecological characteristics also make butterflies promising biodiversity indicators: (i) they have short (typically annual) life cycles and are thus more sensitive than other groups to changes in their habitats (van Swaay and Warren, 1999; Thomas et al., 2004); (ii) they breed in small habitat patches and are likely to reflect changes occurring at a fine scale (van Swaay et al., 2006); (iii) they may be expected to be representative of a wide range of terrestrial habitats (van Swaay et al., 2006), and more importantly to be adequate indicators for many groups of terrestrial insects (Thomas, 2005), which themselves constitute the predominant fraction of biodiversity; (iv) they are exothermic and can thus be expected, despite some physiological and behavioural compensation mechanisms, to react directly to changes in temperature regimes with changes in community composition. Consequently, monitoring the change in abundance and assessing the distribution of butterflies have been suggested as a potential tool for assessing large-scale biodiversity trends (Thomas, 2005; van Swaay et al., 2006).

Compared to many vertebrates, butterfly populations are subject to considerable annual fluctuations induced by both inherent population dynamics and environmental variation, such as weather patterns (Pollard, 1988; Roy et al., 2001). As a consequence, longer time-series are typically required to distinguish between annual fluctuations and systematic, long-term temporal trends (van Strien et al., 1997; Thomas, 2005).

1.3 Current and potential uses of UKBMS for conservation policy and delivery Through discussions with project stakeholders and a review of policy documents, the primary requirements of butterfly monitoring have been identified to be: UK BAP and Habitats Directive reporting, site condition monitoring of SSSIs, publishing and developing biodiversity indicators, assessing the impacts of climate change and land- use in the wider countryside, and agri-environment scheme targeting. Roy et al. (2010) provides further details of the use of UKBMS data to address these areas.

2 Methods

2.1 Structure and main functions of the UK Butterfly Monitoring Scheme

There are a number of sampling frameworks and schemes established to monitor the changing status of UK butterflies. They have differing objectives and consequently utilise differing sampling methods. The two methods currently contributing data to the UKBMS are summarised below, further methods are described in Roy et al. (2010).

2.1.1 Site-based monitoring of annual butterfly abundance The UKBMS comprises a network of fixed route sites across the UK where butterfly counts are made over the season using scientifically validated methodologies. Since 1976, 1,878 monitoring sites have been established, with considerable site turnover. In 2010, the UKBMS site network comprised 1,027 sites sampled by a combination of 869 multi-species transects, 41 single species transects, 109 timed counts and 19 larval-web searches. The data are used to derive annual relative abundance indices for each species at each site, which are then combined to derive individual and multi-species indices and trends. The broad purpose of the UKBMS is to assess the status and trends of UK butterfly populations for conservation, research and quality of life. Current important policy and research uses of the data include UK Biodiversity Action Plan (BAP) reporting, butterfly indicators and assessment of climate change impacts.

2.1.2 Butterfly abundance in the wider countryside A potentially significant development for the UKBMS in 2009 was the launch of a new Wider Countryside Butterfly Survey (WCBS). The survey was launched as a reduced effort approach to obtain better data on the abundance of widespread species across the countryside as a whole. The weekly UKBMS transect routes (Pollard walks) are located mainly on semi-natural sites, leading to a concern that declines in numbers of butterflies (as has been seen in other north European countries) (Cowley et al., 1999; van Swaay et al., 2006) and common moths (Conrad et al., 2004; Conrad et al., 2006) in the wider countryside may have been under- estimated.

The WCBS is a conceptual development for the UKBMS in that (1) the sample locations are a stratified random sample of 1-km squares rather than sites chosen by recorders and (2) linear transect routes within 1-km squares are random as opposed to being chosen by recorders (Brereton et al., 2011b).

2.2 Accessing UKBMS data UKBMS data are made widely available. Summary data are made available via the NBN Gateway (as part of the Butterfly for the New Millennium dataset), and the

UKBMS website (www.ukbms.org). A draft data access policy advocates an open policy to data use, encouraging wide applications and collaboration with Butterfly Conservation and the Centre for Ecology & Hydrology to promote appropriate use (in prep).

2.3 Analysis of trends

2.3.1 Models for site-specific annual survey data – species population index The structure of the UKBMS survey, comprising annual counts at a large number of sites, is similar in broad outline to that long-used for other common and widespread taxonomic groups, e.g. breeding birds (Marchant et al., 1990; Fewster et al., 2000; Freeman et al., 2007). Estimation of annual trends in the UKBMS therefore has also followed methods used for other taxa, based on Poisson models (on account of the non-negative integer status of the data) with ‘Site’ employed as a multi-level additive factor (on a logarithmic scale). This naturally accounts for the varying numbers of butterflies at sites which vary greatly in suitability for a species but permits these to vary in constant proportion between years.

The most straightforward models also permit ‘Year’ to be a multi-level factor; trends at each site move in parallel but no constraint is otherwise imposed upon annual changes. This, a ‘Generalized Linear Model’ (GLM), is now easily fitted in widely- available software and has the additional advantage that site turnover and sporadic years missed are easily accommodated (see e.g. ter Braak et al., 1994). Under such models the expected value of the total count Cit for a species at site i in year t as a function of these site ( Si) and year ( Yt) effects is simply:

Equation (1) Log( E( Cit ) ) = Si + Yt

Inverting the link function, imposed to keep fitted values positive, eYt is then adopted as an index of the species’ relative abundance in year t.

The regression slope of log collated index on years was used to measure the trend over time and the significance of this trend was determined by the correlation coefficient between the log collated index and years (Pollard et al., 1995). Further details of trend assessment are found in recent publications (Brereton et al., 2011a; Fox et al., 2011b).

2.3.2 Multi-species indicators Multi-species indicators are constructed by firstly estimating individual species’ trends as above and then calculating the geometric means across contributing species of each year’s index values. The geometric mean (based on an arithmetic mean of the log-transformed species’ indices) means that the combined effects of, say, one species halving in number and another doubling cancel one another out and leave the averaged index unchanged. Time series of population fluctuations of individual butterflies and multi-species indices are often subject to alternating

5 periods of increase and decrease (largely driven by weather) making it difficult to separate patterns of genuine change from annual fluctuations. Consequently, methods that model smoothed trend lines through abundance data are becoming increasingly popular. There are several smoothing methods available such as polynomial regression, splines and Loess estimators which may be summarised as ‘flexible trend models’. The most popular flexible trend models for the analysis of wildlife populations are General Additive Models (GAMs) and these, for example, are used to produce the EBS Bird Indicators. However, GAMs do not present the complete time series and do not account for serial correlation which limits their applicability to butterfly data.

An alternative flexible trend method from the class of structural time series analysis has recently been developed (Visser, 2005) and applied to European birds (Gregory et al., 2007) and European butterflies (Brereton et al., in press) using TrendSpotter software (Visser, 2004). This is the approach currently used to describe and assess changes in the UK, EBS and Scotland Butterfly Indicator annual updates (from 2008). Unlike the GAM approach, the confidence interval of the trend line is not calculated by a bootstrapping method but by application of a time series analysis and the Kalman filter (Visser, 2004). This approach uses one observation per time point (e.g. year or month) and therefore the uncertainty in the estimate of yearly index values (e.g. confidence intervals around each year index) is modelled indirectly in the annual fluctuations. The main advantage of the TrendSpotter analysis however is the calculation of confidence intervals for the differences between the trend level of the last year and each of the preceding years, taking into account serial correlation which is unique for flexible trend methods. This allows short-term trends to be usefully assessed.

TrendSpotter is currently considered the best-available technique in the assessment of Governmental Butterfly Indicators; further details are available in a technical annex to the England Butterfly Indicators (Brereton and Roy, 2010; http://www.jncc.gov.uk/docs/biyp2010_1bTechBackground.doc).

2.4 Indicator development The methodological development of indicators and assessment of trends have been published in detail elsewhere, e.g. • Brereton T. & Roy D.B. (2010). UK Biodiversity in Your Pocket 2010: Technical annex – Assessing change in England, Scotland and UK Butterfly Indicators. In. Defra London; http://www.jncc.gov.uk/docs/biyp2010_1bTechBackground.doc • Brereton T., Roy D.B., Middlebrook I., Botham M. & Warren M. (2011). The development of butterfly indicators in the United Kingdom and assessments in 2010. Journal of Insect Conservation , 1, 139-151.

An updated assessment of all published indicators is given in this report, as is a draft indicator for Wales and an assessment of the potential for measuring species trends

6 for Northern Ireland. The scope for developing a climate change impacts indicator using butterfly monitoring scheme data has also been assessed.

2.4.1 Methods for a Climate Change Indicator using population monitoring data Projected (Thomas et al., 2006) responses of species to temperature increases suggests that rapid climate change poses a serious threat to biodiversity. There is compelling evidence that species are already responding to a warming climate with ranges expanding polewards (Hickling et al., 2006) and shifting uphill (Wilson et al., 2005), as well as consistent advances in species phenologies (Parmesan, 2007). The scientific community and policy makers recognise the need for the development of indicators of the impacts of climate change on biodiversity (Mace and Baillie, 2007).

The impacts of climate change on biodiversity may be summarised into the following (inter-related) responses: • abundance or geographic distribution of species or the communities which they form • species’ phenology • inter-specific interactions (e.g. feeding relationships) • ecological/evolutionary responses (e.g. behaviour, morphology, physiology)

2.4.1.1 Potential consequences of climate change on butterflies Butterflies require body temperatures of 30–35°C for optimal growth and development (Porter, 1982; Shreeve, 1992). Although butterflies have various methods to raise their temperature to this level (e.g. sun basking, coloration, body movement), climate is one of the major factors determining the distribution of these insects. Hence, it has been suggested that climatic warming has already driven the range expansion of many species at the cool margins of their range, both in latitude and in altitude (Parmesan et al., 1999; Warren et al., 2001; Parmesan and Yohe, 2003; Wilson et al., 2005). There are several ways in which climate change may affect butterflies:

1. Direct effects on the physiology: butterflies and their caterpillars have an optimum temperature range at which body processes function best. If the microclimate changes, this will affect their survival and thus have an effect on their numbers and range.

2. Effects on the abiotic environment: apart from the direct effect of coastal areas being flooded through sea-level rise, the most direct effect of climate change will be on soil systems in terms of organic matter and especially water content.

3. Climate change has an impact on the vegetation structure leading to greater vigour in spring/summer grass growth.

4. Larval foodplants change their range. Many specialist butterflies depend on one or two species of foodplant. If their optimal range doesn’t overlap with

the new foodplant range, this can result in a change in the possible future range of such butterflies. This is demonstrated in the example of Purple Bog Fritillary Boloria titania and its larval foodplant Bistort Polygonum bistorta (Schweiger et al., 2008).

5. Species interactions: It is inevitable that range changes for plants and animals will lead to new interactions between species. Changes in temperature may result in asynchrony between food sources and breeding, causing starvation of young that emerge too early. This will mostly affect specialist species and butterflies with complex interactions with other species. In this respect species of the genus Maculinea, having not only foodplants, but also host- ants, can be vulnerable (Wynhoff et al., 2008). Changes and disruptions in the interactions between butterflies and their parasitoids, pathogens and predators are also highly likely (Both et al., 2006; Menendez et al., 2008).

The overall impact of climate change on butterflies will be a new balance of gains and losses: species will tend to expand their range at the cold edge of their distribution, and lose populations at the southern edge (Parmesan et al., 1999). The process of range expansion is already clearly visible in some species for which historical data are available, e.g. Comma in the Netherlands. In the United Kingdom fifteen species have been reported to show a substantial range increase (Asher et al., 2001). As expected by climate change scenarios, especially large and rapid shifts have been recently observed in northern latitudes in Finland, where one third of the studied 48 species had shifted their range >100 km northwards in eight years (Poyry et al., 2009).

2.4.1.2 Indicators of climate change impacts Existing indicators of the impact of climate change on biodiversity have focused on changes in phenology (Spring Index, UK Biodiversity context indicator) and distribution/abundance measured by long-term monitoring schemes (SEBI2010 indicators). We apply two approaches for a calculating climate change indicators to UKBMS population time series.

2.4.1.3 Climate positive and negative species This method follows an approach adopted for the breeding bird climate change indicator (Gregory et al., 2009). The method measures the ratio or difference between the mean trend in population abundance of climate positive and climate negative species. Climate positive species are those that are predicted to expand their range as a consequence of projected climate change, climate negative species are those predicted to reduce in range extent. The method assumes that an expansion (or reduction) of range will be accompanied by an increase (or decline) in population size. The UK Butterfly Monitoring Schemes time series is used to measure the difference in population change of climate negative and climate positive species. The procedure involves: 1. A selection is made of climate-positive and climate-negative species. For butterflies, this selection was based on a climatic risk atlas for European butterflies (Settele et al., 2008). Settle et al (2008) apply a Species

Distribution Model to predict the future distribution of species assuming a scenario of climate change for 2080, termed ‘Business as usual’ (BAMBU). The BAMBU is an intermediate scenario and assumes that policy decisions already made in the EU are implemented and enforced. Species predicted to expand their range in the UK by more than 20% were considered as climate- positive species, species predicted to retreat by more than 20% were considered as climate negative species. 2. A separate composite index based on the (geometric) mean of the yearly population indices for (1) climate-positive and (2) climate-negative species was then calculated. 3. The potential final climate butterfly indicator would be the ratio between climate-positive and climate-negative species.

2.4.1.4 Changes in Community Temperature Index The second method is based on the work of Devictor et al. (2008), developed for bird species in France. In general this method aims to measure changes in community composition in response to climate warming. The procedure involves: 1. For each butterfly species a Species Temperature Index (STI) was obtained from the distribution data from Kudrna (2002) and the climate data as used by Settele et al. (2008). The STI is the long-term average temperature experienced by individuals of that species over its range. This species characteristic is comparable to the Ellenberg values for nutrient and temperature for plant species (Hill et al., 2004). 2. For each UKBMS site and every year, a Community Temperature Index (CTI) was calculated as the average of each individual’s STI present in the assemblage. A high CTI would thus reflect a large proportion of species with a high STI, i.e. more high temperature dwelling species. 3. The year-to-year temporal trend of CTI was then analysed with a Generalized Linear Model, using data from all monitoring sites. 4. The rate of change in CTI from south to north was also estimated. The south- north gradient of CTI was calculated using all transects counted in 2005, although gradients could be measured for other years. The slope of the regression between CTI and latitude was calculated. 5. The speed of change in km.year-1 is calculated, where trends are significant.

3 Results

3.1 Maintenance, support and development of the volunteer network

3.1.1 Volunteer network development Over the project period, there has been a sustained increase in the number of sites contributing to the UKBMS (Figure 1, Figure 2), and therefore greatly enhancing the value of the scheme for measuring changes in butterfly populations.

Figure 1. Map of transect locations – all locations, colour-coded by those recorded in the last 5 years versus those not recorded since 2005.

1100 1000 900 800 700 600 500 400 300 200 100 0 Number of sites contributing data contributing sites of Number 1973 1975 1977 1979 1981 1983 1985 1987 1989 1991 1993 1995 1997 1999 2001 2003 2005 2007 2009

Year

Figure 2. Number of sites contributing to the UKBMS, 1973-2010 – plot of number of sites with data (transect + non-transect) each year.

The overall increase in the number of sites is mainly attributable to increases in the number of sites submitted to the scheme, rather than through new transects being established (Table 2). The electronic system for data capture (Transect Walker) continues to allow the scheme to operate efficiently. However, this bespoke desktop software is time consuming to support and maintain; it is recommended that an online system is developed within the next three years.

Table 2. Sites contributing to the UKBMS

UKBMS 2005-2008 UKBMS 2008-2010 % change UK sites – all years 1534 1742 14 UK sites – final project year 875* 1038** 19 Date received electronically 95% 96% 1 Data received by deadline 75% 85% 12 No. sites used for annual trends 860 1027 19 No. species reported on 49 54 10 *=2007, **=2010

This growth in the schemes has been achieved through support of the network, with specific activities including: 1. Annual reporting through a detailed recorders report, which can be downloaded at http://www.ukbms.org/reportsAndPublications.htm and a UKBMS/Butterfly Recorders conference held each year (in Birmingham), both containing latest trends, research news and feature stories. 2. Maintenance of a technical advice secretariat by telephone which respond to over 500 enquiries per annum. Contributions have also been made to regional monitoring workshops and training events in each country of the UK. 3. A system has been developed to collate timed count and other non-transect monitoring data used in UKBMS reporting.

3.1.2 Refining existing data collection and analysis methodologies Two studies were completed to evaluate the potential to use Distance Sampling methods for butterfly surveys and monitoring. The studies show that the method has good potential to provide absolute abundance estimates for rare species monitoring (as an alternative to mark-recapture studies) and has a valuable in quantifying bias and imprecision in transect counts, but is not viable as a wholesale replacement for transects for multi-species transect monitoring by volunteer recorders. Relevant publications include: • Isaac, N. J. B., Cruickshanks, K.L., Weddle, A. M., Rowcliffe, J. M., Brereton, T. M., Dennis, R. L. H., Shuker, D. M. and Thomas, C. D. (2011). Distance sampling and the challenge of monitoring butterfly populations. Methods in Ecology and Evolution . • Skinner C. 2010. Validating reduced effort methods to assess Chalkhill Blue (Polyommatus coridon) abundance, Unpublished MSc thesis, University of Bangor.

3.2 Wider Countryside Butterfly Survey (WCBS) An objective of the project was to implement proposals outlined in the development plan, subject to further funding being made available. Part-funding was obtained to from JNCC and Natural England to roll out the WCBS in 2009 and repeat the survey in 2010. There were 763 randomly selected squares sampled in 2009 and 686 in 2010, giving reasonable sample coverage (present in >40 squares) for all target wider countryside species except Scotch Argus. Feedback newsletters describing the results of the surveys and the earlier pilot studies are available at http://www.ukbms.org/wcbs.htm . Full details on the design and implementation of the scheme can be found in Brereton et al. (2011b); further papers on specific aspects of scheme design (Cruickshanks et al., in prep) and analysis of the role of species traits and environmental factors in determining butterfly diversity (Chapman et al., in prep) are at an advanced stage of preparation.

3.3 Trends in butterfly populations

3.3.1 UK and country level indices and trends Trends in the abundance of individual species have been calculated each year of the project, and have been updated to 2010 (Table 3). The results are discussed in 5.1 Trends are calculated for the whole of the UK and at country-level where data is sufficient. Species status information is made widely available through the UKBMS website http://www.ukbms.org/keyFindings.htm and via an annual report to recorders.

Table 3. Summary of butterfly trends, 1976-2010 (unpublished) – summary of trends table for annual report. No. No. Collated Collated % change Series 10-yr Species sites years Index 2009 Index 2010 2009-10 trend trend Small Skipper 497 35 42 35 -17 -67*** -71*** Essex Skipper 280 34 33 22 -33 -44 -90*** Lulworth Skipper 14 19 25 15 -40 -86** -93*** Silver-spotted Skipper 25 32 129 229 78 1217*** -33 Large Skipper 584 35 85 110 29 -16 -14 Dingy Skipper 242 35 81 110 36 -39** 3 Grizzled Skipper 169 35 91 79 -13 -42** -11 Swallowtail 5 31 54 186 244 88* -10 Wood White 49 35 14 98 600 -96*** -61 Brimstone 431 35 112 98 -12 15 3 Large White 588 35 219 89 -59 -22 54 Small White 579 35 126 91 -28 -17 -5 Green-veined White 580 35 174 129 -26 -4 21 Orange Tip 432 35 115 138 20 19 19 Green Hairstreak 256 35 76 91 20 -38* -12 Brown Hairstreak 37 28 60 72 20 58 -53 Purple Hairstreak 245 35 126 123 -2 -2 -9 White-letter Hairstreak 117 35 40 49 22 -83*** -26 Black Hairstreak 10 15 138 407 195 86 334 Small Copper 522 35 95 132 39 -21 42 Small Blue 126 33 148 126 -15 9 37 Silver-studded Blue 45 32 120 110 -8 5 -30 Brown Argus 321 35 110 204 85 22 53 Northern Brown Argus 32 32 56 62 11 -59* -44 Common Blue 584 35 91 224 146 2 16 Chalk-hill Blue 140 35 81 141 74 14 21 Adonis Blue 73 32 151 263 74 172* 99 Holly Blue 461 35 55 141 156 157 -29 Duke of Burgundy Fritillary 84 31 34 40 18 -51* * -71* White Admiral 173 35 71 135 90 -54** 80 Purple Emperor 47 32 117 132 13 21 -15 Small Tortoiseshell 559 35 52 55 6 -66** -72 Peacock 556 35 132 93 -30 44 -9 Comma 540 35 234 162 -31 300*** 11 Small Pearl-bordered Fritillary 122 35 69 95 38 -59*** 16 Pearl-bordered Fritillary 92 35 47 62 32 -74*** -41 High Brown Fritillary 53 33 44 36 -18 -44 -69* Dark Green Fritillary 249 35 162 200 23 129** 99 Silver-washed Fritillary 280 35 174 245 41 104** 137 Marsh Fritillary 77 30 115 269 134 41 4 Heath Fritillary 37 30 28 34 21 -76*** -72* Speckled Wood 530 35 200 132 -34 141*** 33 Wall Brown 279 35 52 41 -21 -81*** -57* Scotch Argus 17 32 107 112 5 137* -50 Marbled White 388 35 91 83 -9 63* -17 Grayling 122 35 91 120 32 -56*** 26 Gatekeeper / Hedge Brown 521 35 74 72 -3 -27 -37 Meadow Brown 605 35 85 68 -20 7 -23 Small Heath 428 35 66 105 59 -56*** 5 Large Heath 12 21 209 269 29 316*** 171* Ringlet 561 35 204 191 -6 334*** 51

Trends in population abundance, as measured by the UKBMS, is presented alongside trends measured from distribution recording (Butterflies for the New Millennium) in the forthcoming update to the State of Britain’s Butterflies (Fox et al., 2011a) and has been used to produce a revised Red List of British butterflies (Fox et al., 2011b) and an assessment of butterfly trends in Scotland (Brereton et al. in press).

3.3.2 Trends in published butterfly indicators Government adopted Butterfly Indicators have been updated annually from 2008- 2010 for the UK, England and Scotland. Further details of published indicators can be found via the following links: http://www.jncc.gov.uk/pdf/BIYP_2010.pdf (UK), http://www.defra.gov.uk/evidence/statistics/environment/biodiversity/4-butterfly- populations.htm (England) and http://www.snh.gov.uk/docs/B424909.pdf (Scotland).

The indicators show that as a group, habitat specialist species have declined, whilst wider countryside species have remained stable or increased (Figure 3, Appendix 1).

Figure 3. Trends in country-level butterfly biodiversity indicators

3.3.3 Development of butterfly indicators for Wales and Northern Ireland

3.3.3.1 Wales A draft indicator for Wales has been developed for a separately funded project ‘Development of an indicator for the range and diversity of wildlife in Wales’ led by Bangor University. Although not directly funded by this project, CEH and BC contributed analysis of UKBMS data to provide context to indicator development for Wales; the results presented here did not directly form a part of the draft biodiversity indicator for Wales. However, a composite, multi-species indicator derived from UKBMS data for Wales (Figure 4) shows a decline in the mean index of

14 specialist butterfly species between 1976 and 2008, in contrast to the mean index of generalist species which are more stable over this period.

2.5

1.5

1 Log Log Index

0.5

0 1970 1975 1980 1985 1990 1995 2000 2005 2010

Year

Figure 4. Trends in butterfly populations in Wales for habitat specialists (red), generalist (wider countryside) species (green) and all species combined (blue), 1976- 2008.

For most species, data since 1976 was used to develop the indicator; figures in brackets indicate where a different start year was used. The criterion for inclusion (as applied to all country indicators) was five or more sites with an index of abundance each year. The following species were included in the index: Small Tortoiseshell; Orange Tip; Ringlet (1983); Dark Green Fritillary; Small Pearl-bordered Fritillary (1992); Green Hairstreak (1993); Holly Blue (1996); Small Heath; Small Blue (1995); Grayling; Brimstone (1995); Small Copper; Meadow Brown; Gatekeeper; Peacock; Large Skipper; Speckled Wood; Wall Brown; Large White; Green-veined White; Small White; Comma (1992); Common Blue; Small Skipper; Red Admiral; Painted Lady (1994)

Species which did not meet the criterion, yet have the potential for future inclusion are: Dark Green Fritillary, High Brown Fritillary, Pearl-bordered Fritillary, Silver- washed Fritillary, Brown Argus, Dingy Skipper. These species have benefited from regional development of transects in Wales since 2004 and all are now well monitored at between 5 and 10 transect sites. The notable omission from this list of priority species in Wales is the Marsh Fritillary, which requires further development work to incorporate data from the larval web monitoring network established by Countryside Council for Wales since 1984.

3.3.3.2 Northern Ireland Transect recording in Northern Ireland has typically been low; in total, 23 sites have been monitored over the whole series. However, a marked increase in monitoring activity has resulted from regional development activity. Prior to 2004, five sites were regularly recorded since 1994. Since 2004, 12-18 sites have been sufficiently well monitored to allow site indices to be calculated. However, on a species-by- species basis there are few sites with data to allow the calculation of a Northern Ireland collated index. No species in Northern Ireland have been monitored at a sufficient number of sites to allow a national index to be calculated using the current analysis methods. With further regional development, combined with the development of novel analysis methods to utilise all monitored sites (e.g. including those with a high proportion of missed recording weeks each season, and Wider Countryside Butterfly Scheme sites), we estimate that there is potential to derive national indices of abundance for the 10-14 most common species and therefore develop a butterfly indicator for Northern Ireland.

3.3.4 Climate Change Indicator using population monitoring data

3.3.4.1 Climate positive and climate negative species The advantage of this method is its simplicity and ease of application. However, limitations are that there are relatively few climate negative species in the UK, and these are not extensively monitored due to their ranges being in northern, under- recorded parts of the country. Furthermore, the trends for climate positive and negative species were similar and not readily interpretable; the resulting ratio showed large year to year fluctuations, without a clear trend being visible. This method might give different results if climate positive and negative species were not selected by their expected future change in distribution, but by observed recent range shifts (e.g. Poyry et al., 2009), or if climate sensitivity was classified based on the response of population abundance to weather and climate factors (e.g. Roy et al. 2001). Also the use of climate envelope models for the prediction of future distribution changes is under debate (Beale et al., 2008). Climate envelope models make a number of simplifying assumptions, such as species are at equilibrium with their environment and populations are not locally adapted to their climate. Although these assumptions do not hold for all species in all situations, species distribution models remain the primary tool for predicting future impacts of climate change on species ranges.

Composite index index Composite

Year Figure 5. Fluctuations in composite indice of groups of climate positive and climate negative butterfly species

3.3.4.2 Changes in the Community Temperature Index (CTI) The CTI method, developed by Devictor et al. (2008), has been shown to be effective at showing change in bird community composition in France. When applied to UKBMS data, a significantly positive trend over time in CTI is apparent (a 0.016 annual change in CTI between 1990 and 2007) with communities becoming more dominated by butterflies characteristic of warmer areas in Europe. As the CTI rises, this can be either by species with a low STI declining, species with a high STI increasing, or a mixture of both. This report does not distinguish between those possible trends, but based on other analysis of recent changes in butterfly populations (e.g. Warren et al., 2001) it is likely that the observed increase is driven by expanding southern species, i.e. communities are becoming more dominated by expanding, generalist, species whose range extends further south in Europe. Such a pattern supports the prediction that changes in distribution (Settele et al., 2008), are preceded by changes in butterfly communities.

CommunityTemperature Index(CTI)

Year

Figure 6: Temporal trends in Community Temperature Index (CTI) ± standard error.

3.3.5 European indicators UKBMS data has contributed to European butterfly biodiversity indicator initiatives, including (1) the development of a grassland butterfly indicator, used by the European Environment Agency to assess progress towards the European 2010 biodiversity target. The indicator can be viewed at http://www.eea.europa.eu/data- and-maps/figures/grassland-butterflies-2014-population-index-1990 and (2) testing the development of a climate change indicator for Europe (CTI measure described in 3.7.4).

Selected publications include: • Brereton, T.M., van Swaay, C. & van Strien, A. 2009. Developing a butterfly indicator to assess changes in Europe’s biodiversity. Proceedings of the 17th International Conference of the European Bird Census Council, Bird Numbers 2007. Avocetta ,33, 19-27. • Devictor V, van Swaay C, Brereton T, Brotons L, Chamberlain D, Heliölä J, Herrando S, Julliard R, Kuussaari M, Lindström Å, Reif J, Roy D, van Strien A, Settele J, Schweiger O, Stefanescu C, Vermouzek Z, van Turnhout C, Wallis de Vries M, Wynhoff I, Jiguet F (submitted). Differences in the climate debts of birds and butterflies at continental scale. Science. • Van Swaay, C.A.M., Van Strien, A.J., Harpke, A., Fontaine, B., Stefanescu, C., Roy, D., Maes, D., Kühn, E., Õunap, E., Regan, E., Švitra, G., Heliölä, J., Settele, J., Warren, M.S., Plattner, M., Kuussaari, M., Cornish, N., Garcia Pereira, P., Leopold, P., Feldmann, R., Jullard, R., Verovnik, R., Popov, S., Brereton, T., Gmelig Meyling, A., Collins, S. 2010. The European Butterfly Indicator for Grassland species 1990-2009. Report VS2010.010, De Vlinderstichting, Wageningen.

• Van Swaay CAM, Harpke A, Van Strien A, Fontaine B, Stefanescu C, Roy D, Maes D, KühnE, Õunap E, Regan EC, Švitra G, Heliölä J, Settele J, Musche M, Warren MS, PlattnerM, Kuussaari M, Cornish N, Schweiger O, Feldmann R, Julliard R, Verovnik R, Roth T,Brereton T, Devictor V. 2010. The impact of climate change on butterfly communities. Report VS2010.025, Butterfly Conservation Europe & De Vlinderstichting,Wageningen.

3.3.6 Uses of UKBMS data in conservation & research (summary of data use) Data from the UKBMS is a widely used resource for research projects aiming to understand the dynamics of wildlife populations or the impacts of environmental change. Below is a list of major research collaborations in which the UKBMS is a major component.

3.3.6.1 Impacts of climate change The impact of climate change on habitat use: implications for predicting species' range changes (NERC/EHFI grant 2008-2011)

Phenological synchrony and species’ range shifts (NERC/NE/UKPopNet, 2009-2010)

Shifting Phenology: Attributing Change across Ecosystems – SPACE (CEH, 2008-2010)

The Biodiversity Impacts of Climate Change Observation Network - BICCO-Net (Defra/JNCC/CCW/SNH, 2009-2011)

Metapopulation dynamics and climate change in a model system: the silver-spotted skipper (NERC/Standard grant, 2009-2012)

CLIMIT: CLimate change impacts on Insects and their MITigation (BiodivERsA, an ERA-net project within the EU FP6 programme, 2009-2012)

Adaptation for future climate warming: the role of habitat creation in promoting species’ range shifts (NERC/Standard grant, 2009-2012)

The role of dispersal on species ability to respond to climate change (UEA/York, 2009-2011)

3.3.6.2 Population dynamics A unified approach to studying animal abundance: integrating evolution, ecology and scale dependency (NERC, 2007-2010)

The impacts of parasitoids on Small Tortoiseshell and Peacock population dynamics (Oxford University, Owen Lewis, 2008-2010)

The ecology and population dynamics of Small Heath in upland habitats (Reading MSc studentship, 2009)

The role of pathogens in butterfly population declines: interactions with habitat fragmentation and climate change (CEH, 2008-2010)

Effects of landscape characteristics on the stability and density of bird and butterfly populations at multiple spatial scales (JNCC/NERC/BTO, 2009-2010)

3.3.6.3 Methodological developments Development of Purple Emperor survey methods (National Trust, Matthew Oates)

Investigating the potential of different types of biodiversity indices to monitor and interpret trends in butterfly numbers (Bristol, Alan Feest)

Application of distance sampling methods for butterfly monitoring (CEH, Nick Isaac)

4 Conclusions

4.1 State of UK Butterfly Populations Analysis of long-term trend data shows that for wider countryside species, the majority (15 of 25) show no overall change, whilst equal numbers of species are either increasing or decreasing. In contrast, twice the number of habitat specialist species show a decline compared with an increase (12 versus six), whilst 30% (8 of the 26) show no overall change. Of the 24 UK BAP Priority Species, 21 are habitat specialists. Our analyses show that more than 70% of UKBAP Priority species are in long-term decline (15 of 21 species assessed) since 1976, yet less than 20% (4 of the 21) have declined over the last decade (Table 4).

The decline in habitat specialist species is linked to a range of factors, including habitat loss, changes in land management (including intensification and abandonment of traditional practices), climate change and habitat fragmentation. Habitat specialists tend to be those restricted to semi-natural habitats, whose isolated and fragmented habitat niches are most difficult to maintain in modern landscapes (Asher et al., 2011). For habitat specialists, climate change is expected to be a major additional threat in coming decades and will exacerbate existing problems (Settele et al., 2008). The declines in abundance as measured by the UKBMS, mirror recent declines in range (Asher et al., 2001; Fox et al., 2006). Specialist butterflies have also declining in range and abundance across many parts of Europe (van Swaay and Warren, 1999; Van Swaay and Van Strien, 2008; van Swaay et al., 2010).

In contrast, some species have recovered from long-term declines, in part due to conservation efforts, including the Silver-spotted Skipper (Davies et al., 2005), the Chalkhill Blue (Brereton et al., 2008) and regionally the High Brown Fritillary (Bulman et al., 2008) and the Heath Fritillary (Rosenthal et al., 2011). Successful re- introductions have included the Large Blue (Thomas et al., 2009) and the Marsh

Fritillary in Cumbria (Porter and Ellis, 2011). Targeted management through agri- environment schemes is playing an increasingly important role in helping butterfly populations to recover on agriculturally managed land, although conservation efforts in woodland and on protected land have on the whole been less successful (Brereton et al., 2011a).

More favourable population trends for wider countryside species is also demonstrated in distribution data, where a number of species are expanding their ranges northwards (Fox et al., 2006; Asher et al., 2011), consistent with predicted responses to higher summer temperatures over the period (Roy et al., 2001). The majority of specialist species have not responded in the same way to the warmer summers because of their lower mobility, which limits their potential to find the remaining fragments of suitable semi-natural habitat (Warren et al., 2001).

Table 4. Summary of trends in UK BAP Priority Species

Species Long-term trend (1976-2010) 10-year trend (2001-2010) High Brown Fritillary Decreasing Decreasing Northern Brown Argus Decreasing No overall change Pearl-bordered Fritillary Decreasing No overall change Heath Fritillary Decreasing No overall change Small Pearl-bordered Fritillary Decreasing No overall change Small Heath* Decreasing No overall change Dingy Skipper Decreasing No overall change Duke of Burgundy Decreasing Decreasing Grayling Decreasing Decreasing Wall* Decreasing No overall change Wood White Decreasing No overall change White Admiral Decreasing No overall change Grizzled Skipper Decreasing No overall change White Letter Hairstreak* Decreasing No overall change Lulworth Skipper Decreasing Decreasing Large Blue Increasing No overall change Large Heath Increasing No overall change Marsh Fritillary No overall change No overall change Silver-studded Blue No overall change No overall change Small Blue No overall change No overall change Brown Hairstreak No overall change No overall change Chequered Skipper No trend available No trend available Mountain Ringlet No trend available No trend available Glanville Fritillary No trend available No trend available

4.2 Future development of the UKBMS The development plan for the future of butterfly surveillance and monitoring (Roy et al., 2010) reviewed the current structure and main functions of the UK Butterfly

Monitoring Scheme and its relationship to other butterfly surveillance activity. Firstly, the report reviewed the strengths and weaknesses of the main field methods for assessing butterflies – showing a high priority need for a wider countryside survey component within the UKBMS. Secondly, the report identified the current and potential policy uses of butterfly monitoring data, including UK BAP and Habitats Directive reporting, site condition monitoring of SSSIs, publishing and developing biodiversity indicators, assessing the impacts of climate change and land- use in the wider countryside, agri-environment scheme targeting. Finally, a critical assessment of the current level of butterfly sampling highlighted regional coverage gaps, areas where targeted development work is required and where analytical improvements could substantially improve use of existing data. The report concluded with costed recommendations for future development of the UKBMS and has provided the main tool for building a policy relevant business case for the funding and development of the UKBMS from March 2011 (beyond the 2008-2011 contract).

4.3 A proposal for butterfly monitoring 2011-2014 After several years of research and development, the methods and options for butterfly monitoring in the UK are well established. The report ‘Development plan for the future of butterfly surveillance and monitoring’ (which forms component 3 of the current contract), included an associated cost-benefit analysis of butterfly monitoring options and identified the following priority for butterfly monitoring from 2011-2014.

The proposed scope of the UKBMS for the next three years is to run annual wider countryside sampling to a stratified random design whilst continuing the multi and single species transect sampling on higher quality habitat. The aim over the three year period is analytical integration (through implementing methods to analyse individual count data together with transect data), and greater logistical integration to achieve some improvements in the efficiency of running the scheme. The aim will also be to replace the existing electronic recording systems for transect recording with an integrated online recording system that links both wider countryside and transect data to a single database against which analytical routines will be developed for maximum processing efficiency. The ability to use data from fewer visits will be exploited to encourage improvements in coverage whilst making efficient use of volunteer time.

The main benefits will be: • Annual trends for most BAP and other UK species. These can be used in indicator production, research to address policy questions etc. • Continuation of individual site monitoring and improved knowledge of impact of management regimes on a large number of sites, particularly in semi- natural habitat. • Unbiased annual trends for wider countryside species • Comparison between trends in the wider countryside and semi-natural sites (from full UKBMS transects)

• Improved coverage of under-recorded habitats/regions as such areas can be more easily targeted with the WCBS method. • Increased coverage of sites used for analysis (through inclusion of WCBS sites and full transect sites with missing visits), giving improved statistical power to detect trends and answer policy questions • Improved efficiency and speed of data processing through online recording by allowing with-season data capture. • Enhance recorder feedback through rapid, within-season, reporting

The elements and benefits of the proposed scheme include: • Maintain existing transect/timed count network in UKBMS (c 900- 1100 sites monitored annually by ~1,500 recorders) 1. Annual data points for earlier detection and increased precision for describing species trends – UK BAP reporting 2. Annual trends for most BAP and other UK species. 3. Annual trends by country (Eng., Scot., Wales) and habitat type (Farmland and Woodland), for most species. 4. Large dataset for use in research (e.g. climate change, AE scheme effectiveness, SSSI condition comparison) 5. Individual site monitoring and improvements for benefit of butterflies and wide range of other insects 6. Improved knowledge of impact of management regimes on a large number of sites 7. Systematic site data on habitat and management 8. Maintenance of the network (i.e. to minimise turnover of sites and maintain high data quality) 9. Annual reports and interpretation of changes for stakeholders 10. Wide-scale public engagement with biological recording 11. Continued advice on site butterfly trends feeding into site management.

• Wider Countryside Butterfly Survey (annual, full scale scheme sampling 600+ 1km sqs) 1. Unbiased annual trends for wider countryside species 2. Comparison between trends in the wider countryside and semi- natural sites (from full UKBMS transects) 3. Baseline for additional, targeted surveys (e.g. effectiveness of ELS and/or countryside policies) 4. Large new dataset for research (e.g. climate change, landscape quality, AES targeting etc). • Indicator production 1. Annual indicator updates for UK, Eng., Scot.

• Improved regional coverage 1. Improved coverage of under-recorded habitats/regions 2. More robust indicators in Scot., Wales, NI., Eng regions and the UK 3. Data on more sites and their management

4. Improved dataset for research 5. Increase public participation to conserve and enhance the environment 6. Increasing use of butterfly monitoring data to inform site conservation effiorts

• Develop and implement on-line recording 1. Improved efficiency and speed of data processing by allowing with- season data capture 2. Improved data quality through validation at the point of data entry 3. Enhance recorder feedback through rapid, within-season, reporting

• Improved methods for trend estimates (analysis of section-level, daily counts, weighting of sites within analysis) 1. More extensive use of existing data 2. Increased coverage of sites used for analysis, giving improved statistical power to detect trends 3. Improved habitat trends through section-level analysis of data 4. More representation UK and country trends

5 Acknowledgements We are indebted to the thousands of volunteer recorders who have contributed to the UKBMS and without whom the scheme would not be possible. We also thank the organisations who support the operation of the scheme. The UKBMS is operated by the Centre for Ecology & Hydrology, Butterfly Conservation and the British Trust for Ornithology and funded by a multi-agency consortium including the Countryside Council for Wales, Defra, the Joint Nature Conservation Committee, Forestry Commission, Natural England, the Natural Environment Research Council, the Northern Ireland Environment Agency and Scottish Natural Heritage.

6 References

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Appendix 1 – Long-term and short-term trends in UK butterfly indicators

Indicator No. Time % change over Status assessment spp. Period smoothed series (2009 versus other years) Long -term trends England All butterflies 50 1976 -2009 -19 Moderate decline 1976 -2005 England Specialist butterflies 26 1976 -2009 -45 Moderate decline 1976 -2007 England Generalist butterflies 24 1976 -2009 -12 Stable 1976 -82, Moderate decline 1983 -98 England All farmland butterflies 48 1990 -2009 -42 Moderate decline 1990 -96, 98 -2000 England Specialist farmland butterflies 23 1990 -2009 -36 Moderate decline 1990 -2007 England Generalist farmland butterflies 25 1990 -2009 -47 Moderate decline 1990 -94, Steep decline 1995 -2008 England All woodland butterflies 42 1990 -2009 -65 Steep decline 1990 -2005 (exc. Moderate decline 1993 -4, 98 -01) England Specialist woodland butterflies 16 1990 -2009 -56 Moderate decline 1990 -2008 England Generalist woodland butterflies 26 1990 -2009 -67 Steep decline 1990 -2007 (exc. Moderate decline 1993) Scotland All butterflies 20 1979 -2009 +23 Stable Scotland Specialist butterflies 6 1979 -2009 -44 Moderate decline 1979 -85 Scotland Generalist butterflies 14 1979 -2009 +22 Stable UK Specialist butterflies 25 1976 -2009 -34 Moderate decline 1976 -2006, exc. 1977, 82 -87 (Deteriorating) UK Generalist butterflies 24 1976 -2009 -6 Stable (exc. Moderate decline 1988 -97)

Short -term trends England All butterflies 50 2000 -2009 -22 Moderate decline 2000 -05 England Specialist butterflies 26 2000 -2009 -34 Moderate decline 2000 -07 England Generalist butterflies 24 2000 -2009 -19 Uncertain England All farmland butterflies 48 2000 -2009 -47 Moderate decline 2000, Steep decline 2001 -07 England Specialist farmland butterflies 23 2000 -2009 -31 Moderate decline 2000 -07 England Generalist farmland butterflies 25 2000 -2009 -58 Steep decline 2000 -08 England All woodland butterflies 42 2000 -2009 -59 Moderate decline 2000 -06 (exc. Steep decline 2002 -05) England Specialist woodland butterflies 16 2000 -2009 -38 Moderate decline 2000 -08 England Generalist woodland butterflies 26 2000 -2009 -55 Steep decline 2000 -07 Scotland All butterflies 20 2000 -2009 +6 Stable Scotland Specialist butterflies 6 2000 -2009 +7 Stable Scotland Generalist butterflies 14 2000 -2009 +6 Stable UK Specialist butterflies 25 2000 -2009 -22 Moderate decline 2000 -06 UK Generalist butterflies 24 2000 -2009 -17 Stable