Reasons for declines in farmland birds

Nationally, there are three main reasons for the loss of wildlife on farmed land: 1. Farming has become more specialised. Historically most farms were a mix of grassland and different arable crops. 2. Farming has become much more intensive, with increased applications of fertiliser and pesticides. Herbicides and insecticides reduce numbers of wild plants and insects, thus reducing the food supply for other wildlife, such as birds and mammals. 3. Habitats have been lost through conversion to other land uses, agricultural intensification or through inappropriate or lack of management.

Farming has become more specialised. Historically most farms were a mix of grassland and different arable crops. However, there has been a broad shift to either specialised dairy or arable farming. Many animals cannot find all their needs (food and nest sites) supplied in areas dominated by only a few types of land use.

Farming has become much more intensive, with increased applications of fertiliser and pesticides. Herbicides and insecticides reduce numbers of wild plants and insects, thus reducing the food supply for other wildlife, such as birds and mammals. Highly fertilised land becomes less botanically diverse, while a faster growing and frequently cut sward (eg, silage) provides fewer nesting sites for birds.

Habitats such as chalk grassland, broad-leaved woodland, flower-rich meadows old, unimproved pastures, heathland and river and coastal grasslands have been lost through conversion to other land uses, agricultural intensification or through inappropriate or lack of management (eg, changes in grazing practice). Many plants and animals declined as they could not adapt to the loss of their particular habitat.Land is, of course, being removed from agriculture for housing and road building. However, in SW England, as in other parts of the UK, the major change that affects farmland wildlife is the nature of farming itself, rather than the area lost to development. Mixed farming has been replaced by intensive dairying enterprises in many areas, especially in the west. Low-intensity pastoral farming combined with arable is now less common. The following changes are responsible for the continuing declines in many farmland birds:

Loss of weed seeds - an essential winter food. The change from spring- to autumn-sown cereals and the loss of over-winter weedy stubbles, together with the loss of areas of marginal land and the increased use of herbicides in arable crops, has removed much of this food for birds such as buntings, finches and larks.

Loss of insects - an important food for chicks and many adult birds. Grasshoppers form 75% of the diet of some chicks and sawfly larvae are an essential food for grey partridge chicks. Meadows and pastures are the main habitat for insects but `improvement' of grassland (and arable) by using pesticides and nitrogen-based fertilisers has reduced insect populations and so has been a major cause of declines in species such as grey partridge.

Loss of nest sites - some birds breed in scrub, hedges and trees, others are ground-nesters requiring tussocky grassland or bare or sparsely vegetated land such as spring cereals. Removal of nesting habitats, or management such as drainage or too frequent cutting or high stocking densities, obviously affects birds, with some being unable to breed or, if they do nest, many broods are lost. Ground-nesting species like lapwing cannot find suitable bare ground nesting sites among winter crops.

Changes in the management of wet grassland - many species breed and feed on damp grassland (eg, snipe). Land drainage and the move from traditional wetland management of high water tables and low intensity grazing has made much of this habitat unsuitable for many birds.

Predation

Birds of prey, magpies and other natural predators are often blamed for declines in farmland birds and other wildlife. However, RSPB research found changes in agricultural practice to be the main cause of the loss of farmland birds such as skylark, lapwing and linnet. The most effective means of reversing declines is through land management changes to provide more insect and seed food and nest sites (eg, cirl buntings recovered because farmers improved habitat, not by increasing predator control).

Source: Our South West, WILDLIFE FRIENDLY FARMING GUIDE
http://www.oursouthwest.com/farming/decline.htm

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