Effectiveness of lasers to reduce goose grazing on agricultural grassland
1 November 2019Clausen, Kevin; Marcussen, Luna; Knudsen, Niels; Balsby, Thorsten; Madsen, Jesper
In recent decades, wild goose populations have grown considerably. Geese forage extensively in agricultural fields leading to frequent conflicts with agricultural stakeholders and calls for effective methods to reduce economic impacts. In this study, we explored the use of handheld lasers to displace grazing Barnacle Geese (Branta leucopsis) and Dark-bellied Brent Geese (Branta bernicla) from farmland pastures on the Wadden Sea island Mandø in Denmark. We evaluate the efficiency of the laser to displace geese, the resultant impact on goose usage and the derived effect on pasture vegetation height. The laser was effective in displacing geese from pastures, but range and efficiency were affected by time of day, light conditions, distance and flock size. Fields subject to laser treatments experienced seven times lower dropping densities and had a mean vegetation height that was 3.3 cm taller than control fields where geese were not exposed to lasers. While the use of laser reduced goose exploitation of experimental fields, a simple cost-benefit analysis revealed that the personnel-hours needed to find geese and operate the laser carried economic costs outweighing the potential economic benefits. We discuss the potential in displacing geese with lasers, and suggest conditions when the method may be a suitable way to reduce goose damages locally.