Wider Countryside Butterfly Survey

Strong emphasis has been placed on designing a scheme that is both scientifically sound (by objectively sampling of the countryside through random sampling) and efficient (a scheme with fewer visits to account for the fact that butterfly species are now uncommon across much of the general countryside).

Through consulting widely in 2005/6 and successful pilot years in 2007/8, the method we have come up with is based on the BTO’s Breeding Bird Survey (the ‘BBS’), counting along two parallel 1-km long transects subdivided into 10 sections, located within randomly selected 1-km squares.  The differences being that butterflies are counted in a more restricted area than for birds and at different times of the day. Only 2-4 visits are required compared to 26 on transects.

We are grateful to the BTO and the Centre for Research into Ecological and Environmental Modelling (CREEM - http://www.creem.st-and.ac.uk/) for providing helpful advice on the design of a wider countryside monitoring scheme.

Good coverage was achieved across Great Britain with 310 squares surveyed. In total 181 BBS squares were surveyed by 165 recorders, nearly double the prediction, and only 33 squares received just one visit.  99 squares were surveyed by 86 recorders in the four selected Butterfly Conservation Branches (Highland, Norfolk, South Wales, Somerset and Bristol) with a further 30 completed by staff (total= 129). 50 squares were visited during May-June to pick up early flying species. The majority of squares were in England (258) followed by Wales (31), Scotland (20) and one square in Northern Ireland.

In spite of the poor weather 42 butterfly species were seen across the UK, including nearly all of the target wider countryside species (excluding the White-letter Hairstreak), plus a good range of migrants and rarer species such as the Large Heath and White Admiral. On average nearly 100 butterflies and ten species were seen per square based on two summer visits, showing that taking part in this survey in the future should produce a good diversity of butterflies for recorders. There were, however, 15 squares where the recorder saw no butterflies on single visits, although at the other extreme one recorder in Kent counted a staggering 672 butterflies on one visit.  The most species rich squares were in Norfolk and Somerset both with 15 species recorded on single visits. Of particular interest was the high occupancy rates (percentage squares occupied)  of the Small Heath butterfly (20%) and the Wall Brown (5%) which are UK Biodiversity Action Plan priority species in decline. It wasn’t just butterflies that caught recorder’s eyes - dragonflies were recorded on more than 50% of squares and day-flying moths were recorded on a quarter of squares.

Wider countryside field testing was repeated in 2008 to further refine field methods and to compare abundance and occupancy (number of squares occupied) in common species between 2007 and 2008 a) within wider countryside squares and b) in comparison to transects.

All recorders that took part in 2007 were invited to take part again in 2008. 192 squares were surveyed in 2008- 62% of last year's total (310). The 38% decrease in uptake was mainly due to very unsettled weather in 2008 and uncertainties over the roll out.

On average 11 species and 104 individuals were seen per square based on 2 summer visits, which is the same as 2007 (10 species and 95 individuals). In total 40 species were recorded in 2008 with 5 species lost compared to 2007 and 3 species gained, all of which are habitat specialists recorded in low numbers. Two key target species of the WCBS are the Small Copper and the Small Heath, both of which increased in abundance and in the number of squares occupied in 2008. The decline in the Small Tortoiseshell was detected using the new method, with 17% fewer squares occupied in 2008. Overall the occupancy figures were relatively stable which is to be expected over a short time scale and provides evidence that the method is robust.

This year the Wider Countryside Butterfly Survey is being launched nationwide. We have set a target of over 1000 squares for the first year. The target will be achieved with the help of BTO recorders surveying their Breeding Bird Survey squares in the summer for butterflies and also through a suite of new 1km survey squares for each BC branch.

The BTO surveys will be organised by the BTO National co-ordinator, whereas Butterfly Conservation surveys will be organised by the WCBS co-ordinator with help from survey ‘Champions’ in each branch. All data will be collated and analysed to achieve a picture of the status of widespread butterflies across the whole UK landscape.

It is likely that the WCBS will occur once every 3 to 5 years in the future. Therefore in the first roll out year, 2009, we need to achieve good coverage to make informed species assessments and demonstrate the usefulness of the data to funders.

To take part in the 2009 survey please contact the WCBS co-ordinator:

Dr Katie Cruickshanks

Butterfly Conservation
Manor Yard
East Lulworth
Wareham
Dorset
BH20 5QP

Tel: 01929 406036
Email: survey@butterfly-conservation.org

To take part on an existing BTO BBS square please contact the BBS National Organiser:

Kate Risely

BTO
The Nunnery
Thetford
Norfolk
IP24 2PU

Tel: 01842 750050
Email: bbs@bto.org

The online data entry system is available to use.
Enter your data online

1. WCBS Guidance for surveys on butterfly only squares (i.e. not BTO BBS squares)
2. WCBS Guidance for BTO BBS recorders
3. WCBS recording form (for all recorders)
4. Landowner letter
5. Health and safety note
6. Insect flower search recording form

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