Fluctuation of Butterfly Numbers between 2004 and 2016

Tony Ruffle and Marcus Jordan have been busy throughout the summer counting butterflies on the regular butterfly transects and an comparison of how the numbers have fluctuated over the last 13 years can be seen in the graph below. A comparison of how two frequent visitors - they gatekeeper and the meadow brown is also shown.

Summary of all butterflies surveyed between 2008 and 2016

Transects carried out by Tony Ruffle and Marcus Jordan

Producing a Butterfly Survey

Trends in butterfly populations are detected by plotting the number of butterflies of each type seen each week between April and September on a number of predetermined routes (transects) across a number of sites nationwide. 

On each site the route is divided into numbered sections which vary in length, habitat type and management. On weekly walks the number of individuals of each butterfly species counted in each section and submitted to Butterfly Conservation.  These are analysed for each species to give 'annual indices of abundance' which are measures of population size. Site indices are combined to calculate regional and national collated indices. These can be plotted over time to detect trends in butterfly populations. 

The two examples shown are graphical representations of the total butterflies seen in Jubilee Country Park in 2008 and acomparison of two species: the Common Blue and the Holly Blue on their breeding success during the season. Click here for more information about the  UK Butterfly Monitoring Scheme

Survey of all butterflies seen on the Jubilee Country Park transect for 2008


The two peaks show the two broods of the Common Blue and the Holly Blue butterflies. You can see that the second generation of the Common Blue was much more successful than the first whereas the Holly Blue was not nearly so successful.


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