Farmland birds in Scotland

• Monitoring of new agrienvironment scheme entrants in Scotland revealed an increase in breeding birds of 29% over five years (54% for songbirds).
• Farms providing over-winter food supplies showed an average increase in breeding yellowhammer numbers of 51%, compared with 28% on control farms.

We have two principal studies in Scotland that focus on farmland songbirds, both of which are looking at aspects of Scotland’s main agri-environment scheme, the Rural Stewardship Scheme (RSS). For five years we have monitored songbird numbers at four sites in East Lothian, starting just after the farmers signed up to the RSS, and for three years we have investigated the impact of winter food availability - including that provided by the unharvested crop (very similar to game crops) prescription in the RSS - on the number of breeding yellowhammers in eastern Scotland.

When our surveys began in East Lothian in 2003 on our RSS monitoring sites, prescriptions had not been put in place so the number of birds seen were representative of numbers on typical conventional farms. With the exception of 2004, annual monitoring since then has recorded the change in breeding bird numbers as the prescriptions became established and matured.

These prescriptions included grass margins, unharvested crops and changes to hedgerow management. Early morning visits to the farms in the spring and summer revealed good numbers of typical farmland species such as skylark, yellowhammer and whitethroat. Overall, we saw 47 species (35 songbird species and 12 species of waders, gamebirds, pigeons, raptors and waterfowl).

Most importantly these surveys revealed a steady increase in bird numbers: up to 2007 the total number of birds seen, and the number of songbirds seen, increased significantly by 29% and 54% respectively, equivalent to average annual increases of 7% and 11% (see Figure 1). At the end of 2008 we hope to compare bird trends on the study farms with bird trends on farms across Scotland as recorded by the British Trust for Ornithology’s Breeding Bird Survey.

Figure 1. Bird counts on Rural Stewardship Scheme sites in Scotland

2003
2005
2006
2007

Our experiment looking at the impact of winter food on the number of breeding yellowhammers is now in its third year and progressing well. We have taken 32 farms in eastern Scotland from Aberdeenshire to the Lothians and altered the availability of grain during the winter.

None of them provided any meaningful winter feeding prior to the experiment: eight farms now provide a two-hectare crop of wheat that is left through the winter, eight put down grain-rich tailings from mid-January to mid-April, eight provide both forms of feeding and eight farms have been left unchanged. This design gives us farms providing food primarily in the first half of the winter (wheat crop only), farms with food available later in the winter and early spring (tailings only), farms with food available throughout (both methods of food provision) and farms with no additional food provided.

On average, the number of breeding yellowhammers has increased from 2005 to 2007 in all four treatment groups, probably reflecting the mild winters over the last few years (see Figure 2). The farms without any additional food have shown an average increase of 28% compared with 51% across all fed sites, although this difference is not significant. This is a complex picture that we hope will be clarified after the final year counts in 2008.

Figure 2. The impact of winter food on yellowhammer breeding numbers

2005
2006
2007