Of the 21 species associated with farmland in Sweden, 15 (71%) displayed a significant decline (P < 0.05) in numbers between 1976 and 2001. Farmland specialists and generalists differed in their population trend estimates. The total declines based on the geometric mean for farmland specialists and generalists were 55% and 7%, respectively. Only the greenfinch Carduelis chloris L. increased significantly in numbers, whereas five species showed non-significant population trends. Seven species experienced average population declines of more than 50% (curlew Numenius arquata L, stock dove Columba oenas L., wryneck Jynx torquilla L., skylark Alauda arvensis L., northern wheatear Oenanthe oenanthe L., house sparrow Passer domesticus L. and linnet Carduelis cannabina L.) of which the curlew experienced the greatest decline (average yearly decline of 7%). Our analyses showed that several farmland specialists have remarkably similar population trends in Sweden and England (e.g. skylark, linnet and yellowhammer Emberiza citrinella L.). This supports the view that the cause of the decline is connected to agriculture and that species with specialist requirements are most sensitive to agricultural change.
Johan Wretenberg (2006) The Decline of Farmland Birds in Sweden. Doctoral thesis,
Swedish University of Agricultural Sciences, Uppsala (attached)