The protozoan parasite responsible for finch trichomonosis has caused epidemic mortality in Greenfinches and Chaffinches across the British Isles. A new study, which uses data from GBW, GBFS and BBS, shows that the British population of breeding Greenfinches has fallen from approximately 4.3 million to 2.8 million birds since the disease’s emergence in 2005, and that the number of Greenfinches visiting gardens has also halved during this time. Chaffinches have been less severely affected. Trichomonosis initially took hold in central and western parts of England and Wales, before spreading east and north into Scotland from 2007 onwards. Incidences were reported in Ireland from autumn 2007. This geographical expansion is thought to have occurred with the seasonal movements of infected individuals. The study’s authors suggest that trichomonosis might have jumped to finches from Woodpigeons. Pigeon and dove populations are traditional reservoirs of this parasite and, as they have similar food preferences, the spill-over from Woodpigeons to finches, and subsequent transmission between finches, could have taken place at shared feeding sites. This study has important implications for managing the on-going impact of the finch trichomonosis epidemic, and for assessing the likely effect of any future wildlife disease outbreaks.

Publicly funded agri-environment schemes are widely used in Europe to address biodiversity losses in farmland ecosystems, but to date evidence of their effectiveness has been limited. New research by the BTO has used BBS data to show that since 2005, management to enhance winter seed availability for farmland birds in England as part of Environmental Stewardship (ES) has significantly reduced the rate of population decline for several species, including Yellowhammer, Linnet, Reed Bunting and Grey Partridge. The types of management involved (leaving stubble overwinter and planting wild bird seed crops in field margins) were mostly implemented under the “broad and shallow” Entry Level Stewardship (ELS) scheme. In keeping with previous research, which indicated that winter food shortages are the most important factor in many farmland bird population declines, measures to enhance breeding habitat, such as providing field margins and managing hedges, had little effect across species. Although significant, the positive effects of stubble and wild bird seed were small, and only slowed population declines rather than reversing them, suggesting that greater uptake of ES is still needed to see national growth of farmland bird populations. Revisions to ES, such as adapted options aiming to fill the late winter “hungry gap”, will also probably be needed.

European agri-environment schemes provide prescriptions to farmers to sustain wildlife and biodiversity on farmland. Such prescriptions include leaving areas of farmland un-cropped. While many studies have investigated the value of different types of un-cropped land for wildlife, little is known about the quantity of un-cropped land needed per farm to maintain bird populations. New work by the BTO, the Game and Wildlife Conservation Trust, Rothamsted Research and NIAB-TAG has sought to address this by examining un-cropped land in 28 arable farms, at a scale consistent with many national monitoring schemes. The average area of un-cropped land was found to be significantly associated with the abundance of key declining farmland bird species, especially Skylark, Linnet and Yellowhammer. Overall, farms in which at least 10% of land area was left un-cropped supported bird populations that were approximately 60% larger than farms with less than 5% un-cropped land. This effect was stronger on conventional farms than on organic farms. There was also some indication that birds responded positively to un-cropped land that was managed more closely to enhance biodiversity. Alongside other recent BTO studies, this work sheds new light on the prescriptions required for stabilising declining populations of farmland birds. In particular it demonstrates the imperative need for sufficient habitat quantity and spatial management, in addition to habitat quality, in European agricultural policy prescriptions.