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The effect of organic farming regimes on breeding and winter bird populations - OC8958

The main objective of the study is to determine whether or not organic farming systems are beneficial to bird populations. Specific objectives involve quantifying the differences between organically and conventionally managed farms/fields in terms of: community composition of breeding and wintering birds between mixed and arable farms; avilability of feed sources in arable fields; and the breeding productivity, foraging behaviour and diet of selected species. Two further objectves involve assessing mechanisms underlying any observed differences and quantifying differences in the farming practices, cropping patterns and non-crop habitat composition on organically and conventionally managed farms (BTO 1990 and 1992).

OC8958. The effect of organic farming regimes on breeding and winter bird populations.

This study will aim to assess whether bird populations on organic farms differ from those on nearby conventional farms and to examine any likely causes of such differences, in relation to habitat, food sources and farming practices. Breeding and winter bird populations will be studied on 44 organic and conventional farms, paired by geographical location and also, as far as possible, in terms of farm area and coarse-grained physical features such as amount of non-crop habitat and field size. Bird abundance will be expressed as densities for individual species and for all species combined in each field. An intensive study of skylarks will be undertaken on 1 pair of farms, to compare territory distribution, timing of breeding, breeding success and nestling growth rates; faecal sacs of nestlings will be analysed in order to assess the contribution of different invertebrates to the diet. In addition, a comparison of potential food resources, including invertebrate abundance, seed availability and flora in organic and conventional fields will be carried out, mainly on cereal fields, including the 2 farms used in the skylark studies.
Time-Scale and Cost
From: 1991

To: 1995

Cost: £201,689
Contractor / Funded Organisations
British Trust For Ornithology
Fields of Study
Organic Farming