As one of our most visible and colourful insects, we almost take the familiar fluttering flight of our native species for granted. Yet, the true story of the British butterfly is much more to do with the struggle for survival. With declines in both numbers and distribution nationally, it’s a concerning situation but perhaps predictable given the fact that we live in such a nature-depleted country.

But how do we know the numbers? It’s all down to monitoring. Monitoring is the key to understanding how any species is faring, and therefore the driver to find reasons for, and solutions to, the issues identified.

At the CRT, we monitor our butterflies in a method determined by the UK Butterfly Monitoring Scheme. Essentially, our wildlife monitors walk the same route (transect) across the farmland for 26 weeks between mid-April and the end of September. To aid consistency, monitoring is carried out in temperatures on or above 13°C, in dry and mild weather, between 10:45am and 4pm (before 3pm where possible), in sunny conditions for at least 60% of the survey time when temperatures are below 17°C, and at a consistent walking speed. Butterflies are only counted if they are seen within 5m of the surveyor.  

It's quite possible as you read this, that one of our full-time monitors or a dedicated volunteer, is traversing the transect looking carefully for any signs of butterfly life. For example, wildlife monitor Ruth Moss (below), who set up a transect at Turnastone Farm and Awnells Farm in Herefordshire in 2021, has started her third year of butterfly surveying.

“Butterflies are an important indicator species due to their high sensitivity to environmental change. Last year at Turnastone we had much higher numbers of Meadow Browns during early summer, but by August as the drought worsened, numbers declined significantly.”

“Ultimately, as our figures build up over the years and can be better compared against national trends, we hope to see clear indications that regenerative farming practices on the areas we’re monitoring are positive for butterfly numbers, both in terms of abundance and species.”

For those who like to know specifics, Ruth’s monitoring efforts in 2022 revealed a 210% increase in Common Blues, and the Meadow Brown was the most abundant butterfly at Turnastone with 461 individuals recorded. On the other hand, the Small Copper, Holly blue and Brimstone were only recorded once over the whole survey.

Butterfly monitoring has also been carried out at Bere Marsh Farm in Dorset for the past two years, as well as at Lark Rise in Cambridgeshire where our records date back 23 years.

At Bere Marsh, the records show a significant leap from a total of 293 butterflies made up of 17 species in 2021 to 556 individuals from 21 species during 2022. The most frequently recorded species was, like at Turnastone, the Meadow Brown (pictured below).

At Lark Rise Farm in Cambridgeshire, it was a similar picture in 2022, with Meadow Browns doing particularly well during the early summer, but with a significant dip in numbers as the drought began to take hold. Of course, the highlight of 2022 was Volunteer wildlife monitor Val Perrin spotting a rare Camberwell Beauty – a migrant visitor enjoying the summer heatwave.

The meadows at Lark Rise Farm (below) have always been an important habitat for many butterfly species and the butterfly transects show that clearly, with a much higher density of butterflies compared to the 6m grass margins around the rest of the farm. The plans to bring back natural meadows at Bere Marsh will be a positive step for the future of our butterflies in Dorset. While the national decline in butterflies is a huge concern, there’s no doubt that establishing the right kind of habitat means that biodiversity gains can be achieved.

Looking forward to this year’s surveying, all our monitors are expecting to see lower numbers due to last year’s drought. Head of Wildlife Monitoring, Vince Lea explains:

“The very first year of national butterfly monitoring to survey standards took place in 1976 – a year famed for those old enough to remember as the long, hot summer. That year butterfly numbers were high, but the following year they dropped significantly. We might see the same this year, but this is why we monitor so we can understand the trends, and hopefully keep providing our butterflies with the right habitat so we can reverse the declines we’ve been seeing.”

Monitoring Volunteers

Monitoring is vitally important. The first surveys carried out give a base line record of what is present on a farm. Then we continue to monitor species each year to gain insight into how our farming and conservation activities are increasing biodiversity. If you have good knowledge of birds, bats, butterflies, bees, reptiles, small mammals or any kind of farmland wildlife, or would like to develop your skills, please get in touch. 

How you can help

We can’t do it without you. If you want to help us protect local wildlife you can support the CRT in any number of ways, from joining as a CRT Friend to volunteering on one of our farms and attending our events. You can also sign-up to our monthly newsletter 'CRT News' for regular updates from our farms, straight to your in-box.

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Read more about the wildlife and conservation initiatives on our farms here Wildlife Blog