In the summer of 2018, the University of Cambridge and the Wildlife Trust for Bedfordshire, Cambridgeshire and Northamptonshire began a new project to assess the impacts of climate change on butterfly species living on some of the Trusts’ most important reserves. Butterflies are abundant, easy to survey, and sensitive to environmental change, making them an ideal group to study and understand how individuals and communities might respond to our warming climate.
I had the pleasure of leading this project, setting out with an army of volunteers, staff and students to survey four chalk grassland sites which make up part of the North Chilterns Living Landscape Project: Totternhoe Quarry, Totternhoe Knolls, Blows Downs and Pegsdon Hills. Once per month, from May to September, we conducted whole site surveys at each reserve, recording every single butterfly seen. The aim was to establish an accurate picture of which species were present on the sites, and which habitats they were using. For each individual, we recorded the species, broad habitat type, an estimate of the gradient of the ground, the aspect of the slope (if not flat), and measured the shelter afforded by surrounding vegetation and topography. The summer was a phenomenal one for butterflies, with peak numbers in June and July making the surveys take up to four days per site! However, that all meant that we got a lot of data.
Meanwhile, the Trust’s Head of Monitoring and Research, Josh Hellon, was out with his drone, taking high-resolution aerial images of each reserve. Over the winter, three students in Cambridge will be using these images to identify the availability of each broad habitat type and each topographic aspect on the reserves, and comparing these to the habitat types used by different butterfly species on the surveys. This will tell us about the habitat and topographic preferences of each species of butterfly on the reserves.