Effect of cattle trampling on ground nesting birds on pastures: an experiment with artificial nests

1. In semi-natural grasslands, nest trampling by cattle can have a strong effect on hatching success but the relationship linking cattle density, incubation time and nest survival has for now only been hypothesized. 2. Based on an experiment with artificial nests, the objective of this study was to test the theoretical model generally used to estimate nest survival. In spring 2009, we conducted a one-month experiment on permanent grasslands of the French western marshlands grazed at three different stocking rates (1 LU.ha-1, 2 LU.ha-1 and 4 LU.ha-1). 3. The results confirmed that trampling depended on stocking rates. 4. Trampling had a major effect on nest survival (32-85% of nests destroyed). 5. The theoretical model classically used by managers and modellers proved to be a good approximation of the dynamics of nest trampling. 6. Synthesis and applications: We conclude that nest trampling has a major impact on nest survival in pastures and that the use of such a model could help managers to define acceptable levels of cattle densities.