Botham, M.; Roy, D.; Brereton, T.; Middlebrook, I.; Randle, Z.

United Kingdom Butterfly Monitoring Scheme: species trends 2014 version 2

This is the most recent version of this dataset (other versions )
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 2014), 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 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 (2015) is now available.

Publication date: 2016-03-31

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Format of the data: Comma-separated values (CSV)

You must cite: Botham, M.; Roy, D.; Brereton, T.; Middlebrook, I.; Randle, Z. (2016). United Kingdom Butterfly Monitoring Scheme: species trends 2014 version 2. NERC Environmental Information Data Centre.



Study area
Temporal extent
1976-04-01    to    2014-09-01

Provenance & quality

Trends are calculated by performing a linear regression on the annual Collated Indices for each species. Collated indices are calculated from UKBMS data using a log-linear model incorporating individual site indices from all monitored sites across the UK for a given species in a given year. They give a statistical measure of how the abundance of each species has changed on monitored sites since 1976, over the last 20 years, and over the last decade. Because the Collated indices are only calculated for each species in years in which it was recorded on five or more sites, the starting year for the series is later than 1976 for a number of rarer species.


This dataset is included in the following collections

United Kingdom Butterfly Monitoring Scheme (UKBMS) 1976-2014 data

Supplemental information

This is a web page which provides data for each butterfly species at each monitored site. It also provides links to reports, UKBMS related publications and to UKBMS statistics in addition to maps of sites.

Correspondence/contact details

UK Centre for Ecology & Hydrology
Maclean Building, Benson Lane, Crowmarsh Gifford
OX10 8BB
Butterfly Conservation


Botham, M.
Centre for Ecology & Hydrology
Roy, D.
Centre for Ecology & Hydrology
Brereton, T.
Butterfly Conservation
Middlebrook, I.
Butterfly Conservation
Randle, Z.
Butterfly Conservation

Other contacts

NERC EDS Environmental Information Data Centre
NERC Environmental Information Data Centre
Resource Provider
UK Butterfly Monitoring Scheme

Additional metadata

Topic categories
Biodiversity butterflies,  England Lepidoptera,  Northern Ireland Scotland United Kingdom Wales
Species Distribution
Spatial representation type
Tabular (text)
Spatial reference system
OSGB 1936 / British National Grid
Last updated
25 June 2021 18:44