A long-term research project discovered that agri-environment schemes can significantly increase local bird and butterfly populations without negatively impacting food production. Scientists spent a decade closely monitoring the effects of a large-scale Defra-funded experiment at Hillesden, a 1,000-hectare commercial arable farm in Buckinghamshire.
Scientists from the UK Centre for Ecology and Hydrology (UKCEH) spent a decade closely monitoring the effects of a large-scale Defra-funded experiment at Hillesden, a 1,000-hectare commercial arable farm in Buckinghamshire. Beginning in 2005, this entailed establishing a variety of wildlife habitats, such as seed-bearing plants for birds, wildflowers for pollinators, and tussocky grass margins to support a variety of birds, insects, and small mammals.
The experiment assessed the effectiveness of these agri-environmental measures in reducing biodiversity losses caused by the intensification of UK farming practices since WWII, including declines in species critical to agricultural production such as pollinators and crop pest predators.
Researchers discovered that the majority of species numbers did better at Hillesden than in other comparable farmed landscapes without agri-environment measures over the same timeframes in the longest-running monitoring study of its kind. Between 2006 and 2016, populations of all bird species increased by one-third, compared to an average of just under 13% at other monitored sites, and populations of all butterflies increased by 40% between 2009 and 2017, compared to 21% elsewhere.
Investigating changes in populations over a significant period of time, and comparing these with other sites, means we can be confident that agri-environment options can bring long-term benefits for bird and butterfly populations.
Dr. John Redhead
A previous UKCEH study of six years’ harvesting data found overall yields at Hillesden were maintained — and enhanced for some crops — despite the loss of agricultural land for habitat creation. Abundance of the common linnet more than doubled at Hillesden, while other seed-eating birds that fared better there compared to other sites included yellowhammer and chaffinch. Meanwhile, birds that usually feed on insects benefited from the shelter provided by hedges and grass margins, including the great tit (up 88 per cent) and blue tit (up 73 percent).
Butterflies that did particularly well at Hillesden over the period studied included the gatekeeper, which feeds on grasses, and the green-veined white, which feeds on wildflowers in field margins. The numbers of both species doubled over the period studied.
Although previous scientific studies have shown bird and butterfly numbers are higher where agri-environment options are present, these have tended to be short-term and limited in scale, so it has been difficult to show that the increases are not just down to lots of individuals moving within the local landscape or only providing a short-term boost to for populations.
Dr. John Redhead of UKCEH, the lead author of the new research paper published in the Journal of Applied Ecology, explains: “Investigating changes in populations over a significant period of time, and comparing these with other sites, means we can be confident that agri-environment options can bring long-term benefits for bird and butterfly populations.”
“Hillesden is a typical, large arable farm with conventional agricultural practices in a typical landscape with no large patches of natural habitat. As a result, the results of our long-term study are likely to indicate what can be accomplished on other commercial farms with good agri-environmental planning, implementation, and management.”
UKCEH and the Wildlife Farming Company investigated the resulting changes in bird and butterfly populations at Hillesden, while the British Trust for Ornithology (BTO) and Butterfly Conservation provided data from other farmed landscapes for comparison.
The areas of land removed from food production for the experiment at Hillesden were chosen because they were unprofitable or difficult to farm, and the new habitats encouraged increased pollination and natural pest control, boosting crop yield in those parts of the farm.
Marek Nowakowski of the Wildlife Farming Company says: “The Hillesden study shows that it is possible to balance wildlife conservation with efficient food production. I am confident other farmers could achieve similar results with the right training and advice.”
The researchers monitored populations of 12 widespread bird species and nine butterfly species. The only species that did significantly worse at Hillesden compared to other sites was the small white butterfly — a pest species that feeds mostly on cultivated brassicas like oilseed rape. The study authors say declines may be due to predation or competition as a result of an increase in beneficial species.
Hillesden has preserved the wildlife habitats created during the experiment and incorporated them into a Countryside Stewardship Scheme. It is also one of the farms collaborating with UKCEH to test in-field strips to see how these habitats can boost pest-controlling insect populations and reduce the need for pesticides.
Hillesden estate owner Robin Faccenda says: “In these difficult times, it has never been more important to strike a balance between profitable farming and increased wildlife delivery. My advice to anyone looking to improve the wildlife on their farm is to seek professional advice and to create a variety of high-quality habitats.”
