With significant long-term declines in UK butterfly abundance1, the desire to help by improving private gardens for butterflies and other wildlife has grown rapidly. While there is an abundance of advice from organisations and individuals, few wildlife-friendly gardening practices have been tested scientifically2. A recent study by Butterfly Conservation scientists, Dr Lisbeth Hordley and Dr Richard Fox, set out to provide robust evidence to underpin two commonly recommended practices, allowing grass to grow long and having flowering Ivy in the garden.
Previous research has found that particular garden features, such as the presence of trees and ponds, can increase insect biodiversity. For example, butterfly abundance and species richness positively correlate with a garden quality index derived from 17 different wildlife-friendly features in UK gardens3. More specifically, several studies have shown that flowering plants influence garden visits by butterflies4 and other pollinators5. It has also been demonstrated that garden size and the surrounding landscape can be important influences on the insect communities found in gardens6.
The new Butterfly Conservation research, published in Science of the Total Environment7, used six years of citizen science data from nearly 650 well-recorded UK gardens from the Garden Butterfly Survey. First, the researchers showed that despite a simple, non-standardised design, the Garden Butterfly Survey provides reliable estimates of abundance for butterflies that are commonly recorded in gardens. They also found significant correlations with garden size and the surrounding landscape; butterfly abundance and/or relative species richness were greater in larger gardens and in gardens with larger proportions of woodland and arable farmland in the immediate area, while the amount of urban land-use (which includes other houses and gardens) in the vicinity had a negative impact.