Winter Farmland Birds Survey

Square Survey - Introduction

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The random square survey involved volunteers visiting randomly selected 1-km squares throughout the lowlands of Britain. Bird and habitat recording were undertaken on a patch-by-patch basis within each 1-km square. All non-farmland habitat types were excluded from the survey so in the majority of cases a patch equated to a field, orchard, pig farm or farmyard. Observers made three visits to their square from November to February inclusive and on each visit surveyed as many patches as possible within a four hour time limit. Each patch was assigned a habitat code specific to winter habitats. Habitats were coded on each visit due to the high rate of change due to agricultural operations at this time of year.

The number of squares visited per winter is given below. Note that no square survey work was undertaken in 2001/2002 because the Foot and Mouth disease outbreak was likely to have seriously reduced coverage due to access restrictions. Respectable coverage was still achieved a year later. Within these squares a total of 18,025 habitat patches (= fields, orchards, farm yards) were surveyed at least once, with 14,222, 11,987 and 10,887 surveyed in the three winters respectively. Of these, 6758 were surveyed in every winter. Every winter in excess of 400km² of farmland was surveyed for farmland birds, the majority of which was surveyed three times per winter. Bird surveys generated approximately 30,000 records of over 300,000 individual birds per winter of the 30 target bird species (see Appendix 1 below for totals).

Coverage maps
1999/2000	2000/2001	2002/2003

The table below gives a summary of the occupancy and abundance of the 30 farmland bird species targetted by the Winter Farmland Bird Surveys. Some species were very scarce on random squares (e.g. Tree Sparrow, Corn Bunting) and for these the Winter Walks and Casual Records provide a good source of supplementary information. Many volunteers opted to record optional species, such as the black crows, gulls and woodpigeons and some even agreed to count everything. The third table simply tallies the number of individuals of each optional species. Note that these do not indicate abundance since not all squares surveyed them. Check back in the future for analyses of these extra counts.

A series of more detailed summary pages are provided. From these you can view results for individual species, for individual BTO regions, countries or Government Office regions. Select from the following drop down menus.

 

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