Complete seasonal surveillance of Greylag Goose (Anser anser) foraging behavior on dairy grassland and the effect of limited lethal scaring

Abstract

In northern Norway, an increasing population of Greylag Geese (Anser anser) forages considerably on dairy grassland and can eat up to 60% of the grass (dry matter mass) on a field if allowed to eat undisturbed throughout the growing season. In this study, the seasonal foraging behavior of Greylag Geese on diary grassland was continuously monitored with game cameras from late April to the end of August to be able to pinpoint effective preventive measures to manage, control, and prevent this crop damage. Limited, but regular, lethal scaring was conducted on some fields to reveal the preventive effect of this measure. Foraging from Greylag Geese in a rangeland area was also monitored, and a complete dataset of seasonal foraging behavior of this species is presented here. Greylag Geese foraging on the fields reaches a top between 04:00 and 08:00 h am, all season. Energy and digestibility of the field grass (timothy) did not reveal any correlation with grazing patterns. Greylag Geese do not visit the fields during molting; however, they may visit fields with their chicks to forage. Lethal scaring completely removes visits from Greylag Geese on the fields where this is conducted, while foraging continues if geese are given undisturbed access. In the rangeland area foraging seems to be even and continuous throughout the season, but significantly lower. In the end of June and late July/early August, there is a peak in visits and number of geese per visit on the fields. Preventive and effective measures against crop damage from Greylag Geese must therefore at least be initiated during late June and early August, and between 04:00 and 08:00 am.