Environmental Stewardship and farmland birds: the evidence base

Declines in biodiversity have been observed across many habitats in the UK over recent decades. This is especially true in farmland habitats. Changes in practices have led to huge increases in productivity in farms, but this has come at the cost of biodiversity. Agri-environment schemes developed by Natural England hope to reverse this trend through changes in environmental management practices by farmers and land owners, and have recently been using research methods to understand the most effective means of achieving this.

Some of the most notable declines in farmland biodiversity have been observed in bird populations. Bird diversity and abundance on farmland have been well recorded over recent years. As birds are easy to record, and are generally at the top of the food chain, they are used as an indicator for the health of farmland habitats. The UK Farmland Bird Indicator is made up of 19 species that are dependent on farmland for survival, including grey partridge and linnet. Since 1970, the abundance of these species has, on average, declined by 48% across farmland habitats. Of course, as this is an average, there have been both winners and losers. However, 12 of the 19 species have shown a decrease in numbers, leading to an average decline in biodiversity across habitats.

These declines are worrying as biodiversity is required for resilient ecosystems that are able to buffer changes in climate or environment. Birds themselves play a key role in farmland habitats, providing vital services to farmers and landowners. Pollination, seed dispersal and predation of invertebrates are all carried out by birds. In some cases, insect pest control is highly valuable.

There is no single reason for the declines observed for farmland bird species. Instead, multiple factors have combined and interacted to give greater effects, and species have responded to these differently. The main drivers behind these declines are outlined broadly by changes in farmland and environmental management, weather, and predation. Since 1970, field sizes have increased, field drainage has improved and there have been changes in the crops grown in the UK. These have all contributed to the decline of farmland birds.

Defra’s Environmental Stewardship scheme was launched in 2005 and aims to secure widespread benefits for the countryside. It focuses on environmental management, and in contrast to previous schemes, it is open to all farmers and land managers. This agri-environment scheme could help halt and reverse the declines in farmland bird abundance and diversity through targeted payment systems. One example of this is winter bird food.

Between mid-winter and spring, farmland birds suffer from a lack of available food. This period is termed the ‘hungry gap’, and places additional pressure on populations already suffering the consequences of changed land management practices. Providing supplementary food for bird populations over this period could help tackle this gap, and ensure birds are better able to adapt to other changes in their environment. For the past five years, research work into this has been carried out at Hillesden Farm in Buckinghamshire. Preliminary results from the study highlight the benefit that winter food can have for birds, with the separate provision of food significantly increasing the number of birds surviving over the winter. These positive results have fed into the development of five new Environmental Stewardship options that became available to farmers at the start of this year. So far, almost 60 farms have signed up to deliver winter bird food.

The final results from Hillesden Farm will be available in summer 2013. From these, best practice guidelines and Environmental Stewardship options can be further developed. There is a great need for a solid evidence base to inform policy decisions, and the use of ecological studies from Hillesden Farm is exemplary. This will enable government to be confident in cost-effective decision making, and enable effective practices to be carried out.