Site indices, as a relative measure of the actual population size, for UK butterfly species calculated from data from the UK Butterfly Monitoring Scheme (UKBMS). Site indices are a relative rather than an absolute measure of the size of a population, and have been shown to relate closely to other, more intensive, measures of population size such as mark, release, recapture (MRR) methods. The site index can be thought of as a relative measure of the actual population size, being a more or less constant proportion of the number of butterflies present. The proportion seen is likely to vary according to species; some butterfly species are more conspicuous and thus more easily detected, whereas others are much less easy to see. Site indices are only calculated at sites with sufficient monitoring visits throughout the season, or for targeted reduced effort surveys (timed observations, larval web counts and egg counts) where counts are generally obtained as close to the peak of the flight period as possible and are subsequently adjusted for the time of year and size of the site (area of suitable habitat type for a given species). Wider Countryside Butterfly Survey (WCBS) sites are thus excluded because they are based on very few visits from which accurate indices of abundance cannot currently be calculated. For transect sites a statistical model (a General Additive Model, 'GAM') is used to impute missing values and to calculate a site index. Each year most transect sites (over 90%) produce an index for at least one species and in recent years site indices are calculated for almost 1,500 sites across the UK. Site indices are subsequently collated to contribute to the overall 'Collated Index' for each species, which are relative measures of the abundance of each species across a geographical area, for example, across the whole UK or at country level in England, Scotland, Wales or Northern Ireland. Individual site indices are important in informing conservation management as not all sites show the same patterns for each species and likely reflect a combination of local climate and habitat management at the site. Although the Centre for Ecology & Hydrology (CEH) and Butterfly Conservation (BC) are responsible for the calculation and interpretation of site indices, the collection of the data used in its creation is ultimately reliant on a large volunteer community. The UKBMS is run by Butterfly Conservation (BC), the Centre for Ecology & Hydrology (CEH) and the British Trust for Ornithology (BTO), in partnership with the Joint Nature Conservation Committee (JNCC), and supported and steered by Forestry Commission (FC), Natural England(NE), Natural Resources Wales (NRW), Northern Ireland Environment Agency (NIEA), and Scottish Natural Heritage (SNH). The UKBMS is indebted to all volunteers who contribute data to the scheme. Full details about this dataset can be found at https://doi.org/10.5285/378f0f77-1842-4789-ba15-6fbdf7d02299

his dataset consists of behaviour and distribution data of Lepidoptera from mown chalk grassland boundaries at the Stonehenge World Heritage Site in Wiltshire, UK, between July and August 2012. The landscape consisted of a mosaic of chalk grassland fragments on ancient burial mounds (barrows) and slopes, grassland re-creation fields of different ages since sowing, semi-improved pasture, arable farmland and woodland. In one of the grassland re-creation fields, two large areas were mown and eight 20 m long survey boundaries were set up. Four of these were set up on the edge of one of two mown areas and four were set up in areas of continuous un-mown grass which had dummy 'boundaries' parallel to the mown boundaries. The survey was conducted from the survey boundary and the flight path of individual Lepidoptera was tracked in the area 10 m either side of the survey boundary. Each individual Lepidoptera flight path was surveyed for three minutes. Each boundary was surveyed for a total of 20 minutes on three occasions over a five week period. The sequence of boundaries surveyed was chosen randomly and equal survey effort was allocated to visually searching both sides of the boundary. The order and time of day for surveying each survey area was random so to spread surveys throughout the survey period and throughout the day. Measures of vegetation characteristics and nectar flower availability were recorded for survey areas. Recorded vegetation characteristics included vegetation height and density. Nectar flower availability was measured as the number of flowering units of nectar flowers and numbers of those in the Asteraceae, Fabaceae and Dipsacaceae families. The data were collected as part of a PhD project funded by the Natural Environment Research Council and the National Trust. Full details about this dataset can be found at https://doi.org/10.5285/e3598268-22d7-4913-a736-890728ea858b

Here, we present a comprehensive traits database for the butterflies and macro-moths of Great Britain and Ireland. The database covers 968 species in 21 families. Ecological traits fall into four main categories: life cycle ecology and phenology, host plant specificity and characteristics, breeding habitat, and morphological characteristics. The database also contains data regarding species distribution, conservation status, and temporal trends for abundance and occupancy. This database can be used for a wide array of purposes including further fundamental research on species and community responses to environmental change, conservation and management studies, and evolutionary biology. Full details about this dataset can be found at https://doi.org/10.5285/33a66d6a-dd9b-4a19-9026-cf1ffb969cdb

Collated indices are a relative measure of butterfly abundance across monitored sites in the UK, calculated from data collected by the UK Butterfly Monitoring Scheme (UKBMS). Collated indices are calculated annually for each individual butterfly species that has been recorded on five or more sites in that year. Based on this criterion collated indices have been calculated for the entire UKBMS time series from 1976 to the current year for the majority of species. For some rarer species the time series starts in a later year due to lack of data. Collated indices are calculated using a statistical model that accounts for missing data. The number of sites for each species ranges from 5 to several hundred and varies from year to year. Since 2008 more than 1,000 sites have been monitored across the UK each year. Collated indices are calculated so that we can determine how butterfly populations are changing over time across the UK. This data can be used, for example, to determine where to target conservation efforts and to measure the condition of the UK countryside. Butterflies are recognised as important indicators of biodiversity and environmental change (e.g. as official UK Biodiversity Indicators), and have been used in numerous research studies to understand the impacts of changes in climate and the extent and condition of habitats. Although the UK Centre for Ecology & Hydrology (UKCEH) and Butterfly Conservation (BC) are responsible for the calculation and interpretation of the Collated indices, the collection of the data used in their creation is ultimately reliant on a large volunteer community. The UKBMS is funded by a consortium of organisations led by the Joint Nature Conservation Committee (JNCC). This dataset is updated annually and more recent versions of the UKBMS collated indices are available. Full details about this dataset can be found at https://doi.org/10.5285/009334d6-ee33-43fc-a259-bf4d92fb69dc

This dataset provides the details of all sites which have been monitored as part of the UK Butterfly Monitoring Scheme (UKBMS). Data includes the location within the UK, the length and width of the line transect on each site, and how long the transect has been monitored. The UKBMS started in 1976 with fewer than 50 sites. The number of sites monitored each year has increased to over a thousand since 2008. There is turnover in sites monitored each year and details of the first and last year in which each site was surveyed are given. The majority of site data is provided by recorders at the time a transect is created. The majority of these recorders are volunteers. The Centre for Ecology & Hydrology (CEH) and Butterfly Conservation (BC) collate the data and the UKBMS is funded by a consortium of organisations led by the Joint Nature Conservation Committee (JNCC). Full details about this dataset can be found at https://doi.org/10.5285/8fd064cc-fdd1-4dc1-ad89-d8497e1bcabe

Larval mass and survival data for Meadow Brown butterflies (Maniola jurtina) originating from nine different source populations in the UK and reared under one of two host plant treatment groups (either control or drought stress) in an outdoor insectary at UKCEH under natural environmental conditions. Each individual larva was monitored at three growth check points throughout development: 49 days after hatching (pre-overwintering), 162 days after hatching (post overwintering during larval growth) and 309 days after hatching (late larval growth and pupation phase). Larval masses (mg) were recorded for all individuals that survived up to the second growth monitoring point and the number of larvae that survived until the third growth monitoring point were recorded. Full details about this dataset can be found at https://doi.org/10.5285/f26f391f-a17b-4a0d-85c7-ab8af85c3f1b

Here, we present a comprehensive traits database for the butterflies and macro-moths of Great Britain and Ireland. The database covers 968 species in 21 families. Ecological traits fall into four main categories: life cycle ecology and phenology, host plant specificity and characteristics, breeding habitat, and morphological characteristics. The database also contains data regarding species distribution, conservation status, and temporal trends for abundance and occupancy. This database can be used for a wide array of purposes including further fundamental research on species and community responses to environmental change, conservation and management studies, and evolutionary biology. A more recent version of the dataset is available at https://doi.org/10.5285/33a66d6a-dd9b-4a19-9026-cf1ffb969cdb entitled 'Traits data for the butterflies and macro-moths of Great Britain and Ireland, 2022'. Full details about this dataset can be found at https://doi.org/10.5285/5b5a13b6-2304-47e3-9c9d-35237d1232c6

This dataset provides linear trends, over varying time periods, for the UK Butterfly Monitoring Scheme (UKBMS) Collated Indices of individual butterfly species across the UK. The main statistical values derived from a linear regression (slope, standard error, P-value) are presented for the entire time series for each species (1976 to 2011), for the last 20 years, and for the last decade. In addition a trend class, based on slope direction and its significance, and a percentage change for that time period are provided to describe the statistical trends. These trend data are provided for 59 UK butterfly species. Trends across different time series allow us to determine the long and short-term trends for individual species. This is enables us to focus conservation and research and also to assess species responses to conservation already in place. The Centre for Ecology & Hydrology (CEH) and Butterfly Conservation (BC) are responsible for the calculation and interpretation of this trend datasets. The collection of the underlying UKBMS data is reliant on a large volunteer community. The UK Butterfly Monitoring Scheme is funded by a consortium of organisations led by the Joint Nature Conservation Committee (JNCC). This dataset is updated annually and a more recent version of the UKBMS species trends (2012) is now available. Full details about this dataset can be found at https://doi.org/10.5285/cad2af6c-0c97-414c-8d5f-992741b283cf

This dataset consists of behaviour and distribution data of Lepidoptera at the Stonehenge World Heritage Site in Wiltshire, UK, between 2010-2011. A long term landscape scale grassland restoration and re-creation project has been underway at the site since 2000. 200m long transects were located in the centre of different grassland re-creation fields of different ages, arable land, chalk grassland fragments on slopes and on ancient burial mounds, and semi-improved pasture. Transects were surveyed on three occasions spread across the field season (June to September), and throughout the day and were selected ad-hoc for survey in order to minimise the effect that the time of year and day would have on results. During the survey, the transect was walked at a slow, steady pace allowing five minutes for each 20m section of transect and the number and species of Lepidoptera present 5m either side and ahead were recorded. If Lepidoptera were observed feeding, then the nectar plant species was also recorded. Habitat quality, defined in terms of vegetation characteristics and nectar resources, was quantified throughout each transect by sampling quadrats in each 20m segment of the transect. Vegetation characteristics were measured as vegetation height and density and the percentage cover of bare ground and dead vegetation. Nectar resources were measured in terms of the number and percentage coverage of flowering units, the total number of nectar flowering units and of relevant families (Dipsacaceae, Fabaceae and Asteraceae). The data were collected as part of a PhD project funded by the Natural Environment Research Council and the National Trust. Full details about this dataset can be found at https://doi.org/10.5285/a384bdfb-0bf2-4c3e-80ab-e171f38d503d

This dataset consists of behaviour and distribution data of Lepidoptera from chalk grassland fragments at the Stonehenge World Heritage Site in Wiltshire, UK, in 2011. The landscape consists of small fragments of ancient chalk grassland on slopes and groups of burial mounds (barrows) which have retained many of the characteristic chalk grassland plant and butterfly species. Surveys were located at four of these chalk grassland fragments. At each chalk grassland fragment, four 20 m long survey boundaries, were set up on boundaries with adjacent land cover of either arable land or new grassland re-creation sown in the years 2009 or 2010. Control surveys were also carried out in areas of continuous habitat within the chalk grassland fragment and in the adjoining land cover type. Surveys of Lepidoptera behaviour were carried out from May to July between 10am and 4pm and effort was taken to survey the same site at different times of the day in order to minimise the effect of survey time on behaviour. Standing at the chalk grassland fragment edge the flight path of individual Lepidoptera was tracked in the survey area for up to three minutes. Measures of vegetation characteristics and nectar flower availability were recorded for each plot. Vegetation characteristics were measured as vegetation height and density and the percentage cover of bare ground and dead vegetation. Nectar resources were measured in terms of the number and percentage coverage of flowering units, the total number of nectar flowering units and of relevant families (Dipsacaceae, Fabaceae and Asteraceae). The data were collected as part of a PhD project funded by the Natural Environment Research Council and the National Trust. Full details about this dataset can be found at https://doi.org/10.5285/61561232-3307-470a-b8dc-a923b25e1641