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The Plight of Britains Farmland Birds

by Steve Portugal

Field with margin and hedgerowsBritain's farmland birds have suffered alarming declines over the last twenty-five years. It would appear that their decrease in numbers coincides with a period of rapid intensification in farming in the mid-1970s, and they have continued to steadily drop in numbers ever since. This spring and summer the RSPB, in conjunction with a number of other organisations, has organised a nation-wide survey intended to get a better idea of the status of our farmland birds, and to work with farmers to make their land more wildlife friendly.
There is thought to be six main reasons for the decline in farmland bird numbers:

1) Loss of wild food-plants as a result of herbicide use
2) Change from spring-sown to autumn-sown cereals and the subsequent loss of winter stubble.
3) Insecticide use reducing invertebrate populations.
4) Conversion of pasture to arable land and the resultant decline in soil invertebrate numbers.
5) Land drainage making soil dwelling invertebrates less accessible.
6) Availability of nest sites due to removal of hedgerows.

Tree SparrowAll of these factors are a result of agricultural intensification, and they have affected different species to varying degrees. The Tree Sparrow (Passer montanus) right is the species that has experienced the most dramatic decline in numbers, over a 95% reduction in abundance. The main cause of this decline is the reduction of seed-supply through destruction of food-plants, usually as a consequence of herbicide use. Along with the loss of winter stubble, it means that food supplies are scarce all year-round which has resulted in a probable increase in the mortality of full-grown birds. Those adult birds that do survive harsh winters on reduced food supply then had difficulties locating suitable nest sites, as the hedgerows they had relied on have been lost.

Another once common farmland bird that has hit hard times is the Grey Partridge (Perdix perdix). This species has been badly affected by the use of herbicides and its subsequent reduction of food-plants. The loss of vital insect supplies by insecticides has resulted in an inadequate rate of chick survival. The lack of suitable nest sites has also resulted in increased predation by corvids and mammals on the eggs and chicks. The Lapwing (Vanellus vanellus) has also suffered. A combination of insufficient chick survival and loss of nesting habitats has resulted in a 40% drop in numbers since 1970. A switch from spring-sown crops to autumn-sown crops causes grass and crops to be too mature and dense to provide suitable nesting sites. Land drainage has affected their food supply by drying out the topsoil and making invertebrates less accessible, and earlier harvests mean that lapwing nests are often destroyed by heavy machinery.

The Corn Bunting (Miliaria calandra) left has declined by 85% because of a severe reduction in areas of barley now sown, a crop which is a favoured site for nesting. The adult birds have also suffered losses because of the loss of winter stubble fields and the use of herbicides. It is thought that adult mortality in the winter months is the main cause for a decline in numbers. Many other once familiar birds have also suffered recent declines; Linnets by 54%, Yellowhammers by 54%, Turtle Dove by 70% and Skylark by 52%.

Through direct practical management the RSPB is hoping to reverse the current decline in numbers of farmland birds. Bird Aid is a three-year emergency feeding experiment designed to monitor effects of providing additional food in the winter to farmland birds, across the United Kingdom. The project is primarily aimed at helping Tree Sparrows and Corn Buntings, as they appear to be two species that are suffering adult mortality as a result of a change in farming methods. Bird counts in both summer and winter aim to see whether feeding birds during the winter makes a difference to breeding populations. It is hoped that agri-environment schemes will also increase the numbers of farmland birds. These are government schemes that make payments to support farmers retaining and improving the quality of their farm from a wildlife point of view. Payments can be given for a variety of different things, such as leaving winter stubble, sowing mixtures of seed bearing crops, and not spraying right to the edge of the field (good feeding habitat for birds).

A separate scheme currently being undertaken in Dorset this year is the Purbeck bio-diversity scheme. The project has been running for five years and is helping to protect declining habitats and species (particularly farmland) by offering advice to farmers and landowners on management and agri-environment schemes that help wildlife. The information gathered from the survey will be analysed and compared against an identical survey that was carried out in 1999. The results from the new 2002 survey should enable important areas for farmland birds in the Purbeck to be identified, and target conservation work where it will have the most beneficial impact.

The Volunteer & Farmer Alliance scheme being undertaken nation-wide this year hopes to promote good relations between conservation groups and the farming community. Each farm that is surveyed receives a computerised map showing the territories of all birds of conservation concern, plus a full list of bird species seen on the farm. The farmer will also receive a certificate of participation and information on how to help farmland birds. It is important to remember that no one is blaming the farmers for the decline of farmland birds as the intensification of farming has been driven by agricultural policy. The aim of the project is to strengthen the links between the RSPB and the farming community, and to help farmers achieve the twin aims of food production and conservation, to give Britain's farmland birds a brighter future.

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Steve Portugal is a marine biology graduate from Aberystwyth. He lives in Dorset and has been birdwatching around the country from a very young age. He starts a job with the RSPB shortly, and begins a PhD in Glasgow at the end of the year.