Agri-environment scheme habitat preferences of Yellowhammer Emberiza citrinella on English farmland

Abstract

Agri-Environment Schemes (AES) have been implemented across Europe in an attempt to address biodiversity losses associated with agricultural intensification. For many declining farmland bird species, the reduced availability and suitability of nesting and foraging habitats are thought to play a major role in population declines and some AES have hoped to counteract this by encouraging the provision of such habitats. This study aimed to determine the relative importance of AES on the territory selection of a widespread but declining farmland bird, the Yellowhammer Emberiza citrinella. Yellowhammers were more likely to locate territories in areas containing 'enhanced margins'; i.e. where field margin habitats were sown with wild flowers and/or agricultural legumes. An average of 0.033 ± 0.008 ha of this 'enhanced margin' habitat was present within 100 m of Yellowhammer territories compared to 0.020 ± 0.008 ha within 100 m of random points. This preference may reflect the higher invertebrate chick food abundance associated with this habitat as they contained, on average 46.3% and 36.8% more invertebrate food items than cereal and floral crops respectively. Alternatively, given that chick food abundance was similar between grass and enhanced field margins, this observed preference may be the result of a more open sward structure which increases prey accessibility and improves predator avoidance. Yellowhammers selected territories containing early succession hedgerows, as these constitute the most suitable nesting sites, and preferred territories containing a suitable songpost. Our results suggest that management strategies aiming to conserve breeding Yellowhammers should focus on increasing the coverage of invertebrate rich AES habitats such as floristically-enhanced margins and pollen and nectar plots, and ensure that they are located within typical foraging ranges of cut hedges with elevated songposts.