Does flax Linum usitatissimum positively impact populations of declining farmland birds?

Abstract

Capsule Skylarks and Yellowhammers generally did not preferentially establish territories in flax relative to autumn-sown crops on lowland farmland.Aims To investigate the biodiversity value of flax using farmland birds as indicator species.Methods Field surveys took place annually between 2009 and 2011 in Northern France, during the breeding season. Fifteen 1 km grid squares were surveyed using a grid-transect method during the periods of greatest avian activity. Territories were identified by the presence of singing males, which were assigned to crop types. Pairwise habitat comparisons were performed.Results Our results suggest that flax is not universally beneficial for Yellowhammers and Skylarks in our study area. However there were inter-specific differences in its use: Skylarks established more territories in flax than in oilseed rape, ploughed fields or improved grassland, whereas Yellowhammers mostly avoided flax fields in preference for grassland, ploughed fields and barley.Conclusion Overall, Skylarks and Yellowhammers did not preferentially establish territories in flax relative to autumn-sown crops, although some selection for flax by Skylarks was evident. Further work is required to: (a) quantify breeding success in flax relative to other crops and (b) investigate the effect of flax on territory densities of other species.