How the crop and the crop structure, with special reference to land based renewable crops, can influence the diversity and abundance of farmland birds on a winter stubble field in the north of England

Abstract

Agricultural intensification and the loss of winter stubble fields are widely accepted as the
most widespread reason for the decline of many species of farmland birds. Farming
practices have changed dramatically in the last fifty years and the effects on birds have been
known since the 1970’s. After much research in to this topic, farmland birds, almost a third
of which were species designated as Species of European Conservation Concern, have
began to steadily increase due to the measures taken to reverse this intensification.
Shorter vegetation is likely to enhance foraging efficiency and reduce predation risk
however this varies for particular species. This study is an investigation in to how the crop
and the crop structure can affect the species diversity and abundance of farmland birds.
Ashcroft field, forms part of Newton Rigg estate, which lies near to the town of Penrith in
Cumbria. On Ashcroft field six species of crop were sewn. The field consisted of four land
based renewable crops; landmark, nebula galactica and finola and two food crops; wheat
and barley. This particular field was left fallow over winter from September 2006. From
October 2006 to December of the same year thirty days of flush counts of eleven species of
birds was undertaken.
Birds recorded were the blue tit Parus caeruleus, chaffinch Fringilla coelebs, dunnock
Prunella modularis, feral pigeon Columba livia, great tit Parus major, greenfinch
Carduelis chloris, siskin Carduelis spinus, starling Sturnus vulgaris, tree sparrow Passer
montanus, buzzard Buteo buteo and kestrels Falco tinniculus.
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The relationship between the bird and the crop it was flushed from were analysed using
analysis of variance. Results showed that landmark was the most favoured crop of all six
with nebula being the least favoured.
A comparison between the four land based renewable crops, wheat and barley showed that
there are preferences shown by certain species of birds. This depended on the stubble
density of the crop and also the plant cover. The study also shows the importance of
hedgerows and game cover crops for a large number proportion of the birds recorded.