Seeded ryegrass swards allow granivorous birds to winter in agriculturally improved grassland landscapes

We experimentally managed silage fields to provide abundant seed as a conservation measure for wintering birds. Buntings Emberiza strongly selected seeded ryegrass plots, where they fed predominantly on ryegrass Lolium seed and maintained body weights similar to those on high-quality arable wintering habitats. Bunting usage of seeded plots was positively related to Lolium seedhead density, peaking at October seedhead densities above 400 seedheads m−2. Perennial ryegrass Lolium perenne swards could only provide one early silage crop (cut by mid-late May) if sufficient seed was to be produced, while Italian ryegrass Lolium multiflorum was able to provide two silage cuts and a large seed crop. Mats of lodged seedheads ensured the continuity of seed provision, resulting in high bird usage during late winter, when most seed has been depleted from existing wild bird seed measures. The estimated cost of the measure was comparable to small-plot measures in current English agri-environment schemes. A rotational seeded ryegrass measure should constitute an effective, affordable and widely applicable conservation measure for seed-eating farmland birds in grassland-dominated farmland across NW Europe.