Butterfly Transect

Butterflies are well placed to act as indicators of the state of the environment as they have rapid lifecycles and are sensitive to environmental conditions. The UK Butterfly Monitoring Scheme (UKBMS) was launched in 1976 with a mission to assess the status and trends of UK butterfly populations for conservation, research and quality of life. The UKBMS has transect sites located throughout the UK with data collected each week from April to September.

Prestwood Nature has taken part in the UKBMS since 2006. The Prestwood Nature transect is about 5km long and is separated into 15 sections with each section reflecting different habitats. The transect is walked by a team of volunteers who identify and count all the butterflies they see, following UKBMS methodology to ensure consistency, so that results are comparable from year to year. A detailed description and map of the transect are provided here.

In total, 3203 butterflies were recorded on the transect in 2023. This compares to an average of 2310 butterflies per year in the last 10 years. Twenty-four different species were recorded.



Average from 2013-2022

Meadow Brown



Marbled White









Speckled Wood



Despite variable weather conditions this year, the transect was walked on all 26 weeks of the recording season.

Following the high temperatures and drought last year which affected the larval food plants of many butterflies, numbers this year have been amazingly buoyant. The top five butterflies reported in 2023 compared to the previous 10 years are shown in the table below.

The Browns have done particularly well with the Meadow Brown once again taking the top spot for numbers overall. Interestingly, most butterfly species were seen in larger numbers than usual, including the Red Admiral (64 sightings compared to an average of 10 in previous years). Butterfly Conservation stated that it is definitely a ‘Red Admiral year’ with a huge surge in sightings of this migrant species reported in the Big Butterfly Count.

Butterflies seen in much lower numbers than the average for the last 10 years in our transect included the Common Blue and the Small Tortoiseshell (none reported).

Our findings echo the results of the Big Butterfly Count. Butterfly Conservation reported that the effects of last year’s drought were not as bad as had been feared. However, while the number of butterflies recorded in the Count was the highest since 2019, the longer-term trends show declines for some of the UK’s most common species.

All results from the Prestwood Nature transect can be found in the Annual Reports below.

The butterflies we find

(Click or tap on any picture to view the gallery)
Annual Reports

Detailed reports for each year from 2008 can be downloaded here

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