The UKBMS is an annual scheme for monitoring the status and trends of UK butterfly populations. It is one of the longest running insect monitoring schemes in the world and therefore it is an important resource for understanding changes in insect populations. Of the 59 species of butterfly that regularly occur in the UK, the UKBMS produces population trends for 58 species.
Background
UKBMS was established in 1976 and is a joint partnership between Butterfly Conservation, UK Centre for Ecology & Hydrology (UKCEH), British Trust for Ornithology (BTO) and JNCC. JNCC is one of the UKBMS’s core funding bodies and helps steer and promote the project and the data it provides. JNCC also provides a key link between the scheme and policy makers, as well as creating communication links between schemes through the UK Terrestrial Evidence Partnership of Partnerships (UKTEPoP).
UKBMS would not be possible without the dedication and support of thousands of talented volunteers. Over 3,300 sites were monitored for butterflies in 2023 by approximately 4,000 volunteers who gave up a total of 120,000 hours of their time. Using the Heritage Lottery Foundation figures, the time volunteers dedicated to UKBMS in 2022 was valued at around £3,670,000.
Why do we monitor butterflies?
Butterflies can give insights into environmental change, habitat health and wider insect communities. Butterflies respond rapidly to environmental change, and they are sensitive to subtle environmental changes due to their high degree of specialisation and reliance on weather. Butterflies are found in nearly all UK habitats, are easily identifiable, and show more rapid declines than other taxa such as birds, allowing for a ubiquitous and sensitive indicator with a long history of records and research.
UKBMS data provide site-specific, country and UK-wide population trends for 58 species of butterfly, which contribute to the JNCC official annual statistic on the abundance of UK butterflies and UK Biodiversity Indicators C4a and C6.
The data are also useful for making informed conservation decisions at species and site levels by identifying vulnerable species and their responses to environmental change and management over time. Long term monitoring of butterflies allows us to see where populations are declining (and therefore areas and/or species that need more targeted conservation) and which populations are increasing and doing well (potentially due to successful conservation measures). Due in part to information gained from UKBMS data, population trends show positive results for a number of butterfly species following targeted conservation efforts.
Sampling approach/how are the data collected?
The main source of data comes from weekly walks that occur between 1st April and 29th September when volunteers walk along defined transect routes and count and identify all butterflies that they see.
Counts are also made through the Wider Countryside Butterfly Survey (WCBS) on randomly selected 1km2 grids. These squares include those run by Butterfly Conservation and those involved in the BTO/JNCC/RSPB Breeding Bird Survey (BBS). These squares provide important data on under-recorded habitats and produce co-located data with bird recordings. Butterfly monitoring in these squares follows the same method as the BBS surveys, where volunteers walk two parallel 1km transects within their square in July and August and count all butterflies that they see.
The UKBMS also includes some more rapid approaches targeted at specific species and sites, including weekly transect walks where volunteers only need to count a single or small selection of species. Additionally, timed counts of adult butterflies, egg counts, and larval web counts may be used to record specialist species or for site level data in remote areas to reduce the time requirements needed by the volunteers.
How and where data/results are available to stakeholders
UKBMS publishes annual reports which summarise the data and trends, as well as other reports on their publications page. UKBMS data are held by UKCEH, and the dataset is published each year via the Natural Environment Research Council (NERC) Environmental Information Data Centre.
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