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OFFICIAL STATISTICS

These statistics have been produced to the high professional standards set out in the Code of Practice for Official Statistics, which sets out eight principles including meeting user needs, impartiality and objectivity, integrity, sound methods and assured quality, frankness and accessibility. More information on the Official Statistics Code of Practice can be found at http://www.statisticsauthority.gov.uk/assessment/code-of-practice/index.html.

Click here  to access the 2016 Summary of Changes table for the UK. The table includes trend estimates for Wider Countryside species using a new analytical method which includes Wider Countryside Butterfly Survey data, as described in Dennis et al (2013) Methods in Ecology and Evolution 4, 637-645 doi: 10.1111/2041-210X.12053, and discussed in the 2012 annual report. Indices for Habitat Specialist and Migrant species are calculated using the standard analysis described in detail here. Number of sites monitored is a count of all sites on which a species has been monitored in the current analysis year, including those sites on which a species was absent but has been formerly recorded, and thus contribute to the calculation of the national index. For habitat specialist and regular migrant species only sites with sufficient data to calculate a site-level index for each species are included. As with wider countryside species this includes sites where a species was absent in the most recent year but formerly recorded, if the site has been sufficiently well recorded during the flight period of that species in that year. For those species for which there is currently insufficient data to perform trend analyses, the number of sites monitored is the total number of sites in that year on which that species was recorded, including sites that did not produce an index for that species.

Click here  to access the 2016 Country-level Summary of Changes tables for England, Scotland, Wales and Northern Ireland. The tables include trend estimates for Wider Countryside species using a new analytical method which includes Wider Countryside Butterfly Survey data, as described in Dennis et al (2013) Methods in Ecology and Evolution 4, 637-645 doi: 10.1111/2041-210X.12053, and discussed in the 2012 annual report. Indices for Habitat Specialist and Migrant species are calculated using the standard analysis described in detail here. Number of sites monitored is a count of all sites on which a species has been monitored in the current analysis year, including those sites on which a species was absent but has been formerly recorded, and thus contribute to the calculation of the national index. For habitat specialist and regular migrant species only sites with sufficient data to calculate a site-level index for each species are included. As with wider countryside species this includes sites where a species was absent in the most recent year but formerly recorded, if the site has been sufficiently well recorded during the flight period of that species in that year. For those species for which there is currently insufficient data to perform trend analyses, the number of sites monitored is the total number of sites in that year on which that species was recorded, including sites that did not produce an index for that species. Note: Some country-level changes are based on relatively small sample sizes and thus should be interpreted with caution.


The UKBMS is run by  Butterfly Conservation (BC), the Centre for Ecology and 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.