Spring grazing and the manipulation of food quality by barnacle geese

(1) The foraging activities of a large flock of barnacle geese (Branta leucopsis Bechstein) wintering on the West Frisian island of Schiermonnikoog were monitored during the spring of 1978. On fourteen sites distributed over the grazing area we measured grazing intensity, plant species presence and abundance, standing cropherbage accumulation, and crude protein content of Festuca rubra L., the primary food plant of barnacle geese. Two of the sites had nitrogen fertilizer applied to them. (2) Almost all the sites were grazed repeatedly, but barnacle geese utilized different areas with different mtensities. In spite of this, the standing crops did not differ between sites, and the standing crop on all the sites remained relatively constant throughout the spring, including the sites that received a nitrogen fertilizer. (3) Areas with the highest rates of herbage accumulation were grazed most intensely. Barnacle geese displayed no consistent preference for other site characteristics. (4) High levels of protein in Festuca rubra were a direct result of repeated grazing of sites by barnacle geese, and the consequent sustained regeneration of young, protein-rich plant tissues